





















                                 GGNNUUPPLLOOTT
                     AAnn IInntteerraaccttiivvee PPlloottttiinngg PPrrooggrraamm



                      _T_h_o_m_a_s _W_i_l_l_i_a_m_s _& _C_o_l_i_n _K_e_l_l_e_y
               _V_e_r_s_i_o_n _4_._1 _o_r_g_a_n_i_z_e_d _b_y_: _H_a_n_s_-_B_e_r_n_h_a_r_d _B_r_o_e_k_e_r
                   _M_a_j_o_r _c_o_n_t_r_i_b_u_t_o_r_s _(_a_l_p_h_a_b_e_t_i_c _o_r_d_e_r_)_:
                           _H_a_n_s_-_B_e_r_n_h_a_r_d _B_r_o_e_k_e_r
                               _J_o_h_n _C_a_m_p_b_e_l_l
                             _R_o_b_e_r_t _C_u_n_n_i_n_g_h_a_m
                               _D_a_v_i_d _D_e_n_h_o_l_m
                               _G_e_r_s_h_o_n _E_l_b_e_r
                               _R_o_g_e_r _F_e_a_r_i_c_k
                              _C_a_r_s_t_e_n _G_r_a_m_m_e_s
                                 _L_u_c_a_s _H_a_r_t
                                _L_a_r_s _H_e_c_k_i_n_g
                               _T_h_o_m_a_s _K_o_e_n_i_g
                                 _D_a_v_i_d _K_o_t_z
                                _E_d _K_u_b_a_i_t_i_s
                                _R_u_s_s_e_l_l _L_a_n_g
                             _A_l_e_x_a_n_d_e_r _L_e_h_m_a_n_n
                               _A_l_e_x_a_n_d_e_r _M_a_i
                               _E_t_h_a_n _M_e_r_r_i_t_t
                                _P_e_t_r _M_i_k_u_l_i_k
                               _C_a_r_s_t_e_n _S_t_e_g_e_r
                                 _T_o_m _T_k_a_c_i_k
                             _J_o_s _V_a_n _d_e_r _W_o_u_d_e
                                  _A_l_e_x _W_o_o
                             _J_a_m_e_s _R_. _V_a_n _Z_a_n_d_t
                              _J_o_h_a_n_n_e_s _Z_e_l_l_n_e_r
     _C_o_p_y_r_i_g_h_t _(_C_) _1_9_8_6 _- _1_9_9_3_, _1_9_9_8_, _2_0_0_4   _T_h_o_m_a_s _W_i_l_l_i_a_m_s_, _C_o_l_i_n _K_e_l_l_e_y
        Mailing list for comments: gnuplot-info@lists.sourceforge.net
      Mailing list for bug reports: gnuplot-bugs@lists.sourceforge.net
                              27 March 2012



















                                    -2-








                This manual was prepared by Dick Crawford.
                             3 December 1998





























































   11..  GGnnuupplloott





   22..  CCooppyyrriigghhtt


       Copyright (C) 1986 - 1993, 1998, 2004, 2007  Thomas Williams,
   Colin Kelley

   Permission to use, copy, and distribute this software and its docu-
   mentation for any purpose with or without fee is hereby granted,
   provided that the above copyright notice appear in all copies and
   that both that copyright notice and this permission notice appear in
   supporting documentation.

   Permission to modify the software is granted, but not the right to
   distribute the complete modified source code.  Modifications are to
   be distributed as patches to the released version.  Permission to
   distribute binaries produced by compiling modified sources is
   granted, provided you
     1. distribute the corresponding source modifications from the
      released version in the form of a patch file along with the bina-
   ries,
     2. add special version identification to distinguish your version
      in addition to the base release version number,
     3. provide your name and address as the primary contact for the
      support of your modified version, and
     4. retain our contact information in regard to use of the base
      software.
   Permission to distribute the released version of the source code
   along with corresponding source modifications in the form of a patch
   file is granted with same provisions 2 through 4 for binary distri-
   butions.

   This software is provided "as is" without express or implied war-
   ranty to the extent permitted by applicable law.


         AUTHORS

         Original Software:










   GNUPLOT 4.1                                                        2


            Thomas Williams,  Colin Kelley.

         Gnuplot 2.0 additions:
            Russell Lang, Dave Kotz, John Campbell.

         Gnuplot 3.0 additions:
            Gershon Elber and many others.

         Gnuplot 4.0 additions:
            See list of contributors at head of this document.



   33..  IInnttrroodduuccttiioonn


   GGnnuupplloott is a portable command-line driven graphing utility for
   Linux, OS/2, MS Windows, OSX, VMS, and many other platforms. The
   source code is copyrighted but freely distributed (i.e., you don't
   have to pay for it). It was originally created to allow scientists
   and students to visualize mathematical functions and data interac-
   tively, but has grown to support many non-interactive uses such as
   web scripting. It is also used as a plotting engine by third-party
   applications like Octave. Gnuplot has been supported and under
   active development since 1986.

   Gnuplot supports many types of plots in either 2D and 3D. It can
   draw using lines, points, boxes, contours, vector fields, surfaces,
   and various associated text. It also supports various specialized
   plot types.

   Gnuplot supports many different types of output: interactive screen
   terminals (with mouse and hotkey input), direct output to pen plot-
   ters or modern printers, and output to many file formats (eps, fig,
   jpeg, LaTeX, metafont, pbm, pdf, png, postscript, svg, ...). Gnuplot
   is easily extensible to include new output modes. Recent additions
   include interactive terminals based on aquaterm (OSX) and wxWidgets
   (multiple platforms).

   The command language of ggnnuupplloott is case sensitive, i.e. commands and
   function names written in lowercase are not the same as those writ-
   ten in capitals. All command names may be abbreviated as long as the
   abbreviation is not ambiguous. Any number of commands may appear on
   a line, separated by semicolons (;). Strings may be set off by
   either single or double quotes, although there are some subtle dif-
   ferences.  See ssyynnttaaxx and qquuootteess for more details. Examples:

         load "filename"
         cd 'dir'

   Many ggnnuupplloott commands have multiple options. Version 4 is less sen-
   sitive to the order of these options than earlier versions, but some
   order-dependence remains. If you see error messages about










   GNUPLOT 4.1                                                        3


   unrecognized options, please try again using the exact order listed
   in the documentation.

   Commands may extend over several input lines by ending each line but
   the last with a backslash (\).  The backslash must be the _last_
   character on each line.  The effect is as if the backslash and new-
   line were not there.  That is, no white space is implied, nor is a
   comment terminated.  Therefore, commenting out a continued line com-
   ments out the entire command (see ccoommmmeennttss).  But note that if an
   error occurs somewhere on a multi-line command, the parser may not
   be able to locate precisely where the error is and in that case will
   not necessarily point to the correct line.

   In this document, curly braces ({}) denote optional arguments and a
   vertical bar (|) separates mutually exclusive choices.  GGnnuupplloott key-
   words or hheellpp topics are indicated by backquotes or bboollddffaaccee (where
   available).  Angle brackets (<>) are used to mark replaceable
   tokens.  In many cases, a default value of the token will be taken
   for optional arguments if the token is omitted, but these cases are
   not always denoted with braces around the angle brackets.

   For built-in help on any topic, type hheellpp followed by the name of
   the topic or hheellpp ?? to get a menu of available topics.

   The new ggnnuupplloott user should begin by reading about pplloottttiinngg (if in
   an interactive session, type hheellpp pplloottttiinngg).

   See the simple.dem demo, also available together with other demos on
   the web page
             http://www.gnuplot.info/demo/
   GGnnuupplloott can be started from a command line or from an icon according
   to the desktop environment. Running it from command line can take
   the syntax
         gnuplot {OPTIONS} file1 file2 ...
   where file1, file2, etc. are input file as in the llooaadd command.  On
   X11-based systems, you can use
         gnuplot {X11OPTIONS} {OPTIONS} file1 file2 ...
   see your X11 documentation or rather xx1111 in this document.

   Options interpreted by gnuplot may come anywhere on the line.  Files
   are executed in the order specified, as are commands supplied by the
   -e option, for example
         gnuplot   file1.in   -e "reset"   file2.in

   The special filename "-" is used to force reading from stdin.  GGnnuu--
   pplloott exits after the last file is processed.  If no load files are
   named, GGnnuupplloott takes interactive input from stdin.  See help
   bbaattcchh//iinntteerraaccttiivvee for more details.  The options specific to gnuplot
   can be listed by typing
         gnuplot --help
   See ccoommmmaanndd lliinnee ooppttiioonnss for more details.

   Hit 'h' for help about hhoottkkeeyyss and mmoouussiinngg features in interactive










   GNUPLOT 4.1                                                        4


   screen terminals (ppmm, wwiinnddoowwss, wwxxtt, xx1111).

   Section sseeeekkiinngg--aassssiissttaannccee will help you to find further informa-
   tion, help and FAQ.



   44..  SSeeeekkiinngg--aassssiissttaannccee


   The canonical gnuplot web page can be found at
             http://www.gnuplot.info

   Before seeking help, please check file FAQ.pdf or the above website
   for
             FAQ (Frequently Asked Questions) list.

   If you need help as a gnuplot user, please use the newsgroup
             comp.graphics.apps.gnuplot
   We prefer that you read the messages through the newsgroup rather
   than subscribing to the mailing list which is also available and
   carries the same set of messages. Instructions for subscribing to
   gnuplot mailing lists may be found via the gnuplot development web-
   site on SourceForge
             http://sourceforge.net/projects/gnuplot

   The address for mailing to list members is:
             gnuplot-info@lists.sourceforge.net

   Bug reports and code contributions should be uploaded to the track-
   ers at
             http://sourceforge.net/projects/gnuplot/support
   Please check previous bug reports if the bug you want to report has
   not been already fixed in a newer version of gnuplot.

   The list of those interested in development version of gnuplot is:
             gnuplot-beta@lists.sourceforge.net

   When posting a question, please include full details of the version
   of ggnnuupplloott, the machine, and operating system you are using.  A
   _small_ script demonstrating the problem may be useful.  Function
   plots are preferable to datafile plots.  If email-ing to gnuplot-
   info, please state whether or not you are subscribed to the list, so
   that users who use news will know to email a reply to you.  There is
   a form for such postings on the website.




   55..  NNeeww ffeeaattuurreess iinnttrroodduucceedd iinn vveerrssiioonn 44..44













   GNUPLOT 4.1                                                        5


   Gnuplot version 4.4 offers many new features introduced since the
   preceding official version 4.2. This section lists major additions
   and gives a partial list of changes and minor new features. For a
   more exhaustive list, see the NEWS file.





        55..11..  IInntteerrnnaattiioonnaalliizzaattiioonn


        Gnuplot 4.4 contains significantly improved support for locale
        settings and for UTF-8 character encodings. See sseett llooccaallee, sseett
        eennccooddiinngg, sseett ddeecciimmaallssiiggnn.




        55..22..  TTrraannssppaarreennccyy


        Gnuplot now supports several forms of transparency. Any object
        or plot element that uses a fill style can be assigned a trans-
        parency from fully opaque to fully transparent. Image or matrix
        data can be plotted with an alpha channel using the new plot
        style wwiitthh rrggbbaallpphhaa. See ffiillllssttyyllee, rrggbbaallpphhaa.




        55..33..  VVoollaattiillee DDaattaa


        The new command rreeffrreesshh is similar to rreepplloott except that it
        uses the previously-stored input data values rather than
        rereading the input data file.  Mouse operations (zoom, rotate)
        will automatically use rreeffrreesshh rather than rreepplloott if the input
        data stream is marked vvoollaattiillee.  Piped or in-line data is auto-
        matically treated as volatile.  See rreeffrreesshh, pplloott ddaattaaffiillee
        vvoollaattiillee.




        55..44..  CCaannvvaass ssiizzee



        In earlier versions of gnuplot, some terminal types used the
        values from sseett ssiizzee to control also the size of the output
        canvas; others did not.  The use of 'set size' for this purpose
        was deprecated in version 4.2.  In version 4.4 almost all










   GNUPLOT 4.1                                                        6


        terminals now behave as follows:

        sseett tteerrmm <<tteerrmmiinnaall__ttyyppee>> ssiizzee <<XXXX>>,, <<YYYY>> controls the size of
        the output file, or "canvas". Please see individual terminal
        documentation for allowed values of the size parameters.  By
        default, the plot will fill this canvas.

        sseett ssiizzee <<XXXX>>,, <<YYYY>> scales the plot itself relative to the size
        of the canvas.  Scale values less than 1 will cause the plot to
        not fill the entire canvas.  Scale values larger than 1 will
        cause only a portion of the plot to fit on the canvas.  Please
        be aware that setting scale values larger than 1 may cause
        problems on some terminal types.

        The major exception to this convention is the PostScript
        driver, which by default continues to act as it has in earlier
        versions. Be warned that the next version of gnuplot may change
        the default behaviour of the PostScript driver as well.

        Example:

              set size 0.5, 0.5
              set term png size 600, 400
              set output "figure.png"
              plot "data" with lines

        These commands will produce an output file "figure.png" that is
        600 pixels wide and 400 pixels tall. The plot will fill the
        lower left quarter of this canvas.  This is consistent with the
        way multiplot mode has always worked, however it is a change in
        the way the png driver worked for single plots in version 4.0.




        55..55..  NNeeww pplloott eelleemmeennttss


        The sseett oobbjjeecctt command can now be used to define fixed circles,
        ellipses, and polygons as well as rectangles. There is a corre-
        sponding new plot style pplloott wwiitthh cciirrcclleess.  See cciirrccllee, eelllliippssee
        and ppoollyyggoonn.




        55..66..  NNeeww oorr rreevviisseedd tteerrmmiinnaall ddrriivveerrss


        Two new drivers based on the cairo and pango libraries are
        included, ppnnggccaaiirroo and ppddffccaaiirroo.  These are alternatives to the
        older libgd-based png driver and the older PDFLib-based pdf
        driver.  The figures in the pdf version of this manual were










   GNUPLOT 4.1                                                        7


        prepared using the pdfcairo terminal driver.

        The ccaannvvaass terminal driver produces javascript output that
        draws onto the HTML canvas element of a web page.  It can pro-
        duce either a complete web page containing a single plot, or a
        script that can be embedded as part of an externally generated
        HTML document that perhaps contains multiple plots.  The embed-
        ded plots support browser-side mousing, including zoom/unzoom.

        The lluuaa terminal driver creates an data intended to be further
        processed by a script in the lua programming language.  At this
        point only one such lua script, gnuplot-tikz.lua, is available.
        It produces a TeX document suitable for use with the latex TikZ
        package.  Other lua scripts could be written to process the
        gnuplot output for use with other TeX packages, or with other
        non-TeX tools.

        SSeett tteerrmm ttiikkzz is shorthand for sseett tteerrmm lluuaa ttiikkzz.  As decribed
        above, it uses the generic lua terminal and an external lua
        script to produce a latex document.




        55..77..  NNeeww ssmmooootthhiinngg aallggoorriitthhmmss


        New smoothing algorithms have been added for both 2- and
        3-dimensional plots.  ssmmooootthh kkddeennssiittyy and ssmmooootthh ccuummuull can be
        used with pplloott to draw smooth histograms and cumulative distri-
        bution functions, resp. For use with sspplloott several new smooth-
        ing kernels have been added to ddggrriidd33dd.  See ssmmooootthh ddggrriidd33dd.




   66..  BBaacckkwwaarrddss ccoommppaattiibbiilliittyy


   Gnuplot version 4.0 deprecated certain syntax used in earlier ver-
   sions, but continued to recognize it.  This is now under the control
   of a configuration option, and can be disabled as follows:

         ./configure --disable-backwards-compatibility

   Notice: Deprecated syntax items may be disabled permanently in some
   future version of gnuplot.

   One major difference is the introduction of keywords to disambiguate
   complex commands, particularly commands containing string variables.
   A notable issue was the use of bare numbers to specify offsets, line
   and point types.  Illustrative examples:











   GNUPLOT 4.1                                                        8


   Deprecated:
         set title "Old" 0,-1
         set data linespoints
         plot 1 2 4               # horizontal line at y=1
   New:
         TITLE = "New"
         set title TITLE offset char 0, char -1
         set style data linespoints
         plot 1 linetype 2 pointtype 4




   77..  BBaattcchh//IInntteerraaccttiivvee OOppeerraattiioonn


   GGnnuupplloott may be executed in either batch or interactive modes, and
   the two may even be mixed together on many systems.

   Any command-line arguments are assumed to be either program options
   (first character is -) or names of files containing ggnnuupplloott com-
   mands. The option -e "command" may be used to force execution of a
   gnuplot command. Each file or command string will be executed in the
   order specified.  The special filename "-" is indicates that com-
   mands are to be read from stdin.  GGnnuupplloott exits after the last file
   is processed.  If no load files and no command strings are speci-
   fied, ggnnuupplloott accepts interactive input from stdin.

   Both the eexxiitt and qquuiitt commands terminate the current command file
   and llooaadd the next one, until all have been processed.

   Examples:

   To launch an interactive session:
         gnuplot

   To launch a batch session using two command files "input1" and
   "input2":
         gnuplot input1 input2

   To launch an interactive session after an initialization file
   "header" and followed by another command file "trailer":
         gnuplot header - trailer

   To give ggnnuupplloott commands directly in the command line, using the
   "-persist" option so that the plot remains on the screen afterwards:
         gnuplot -persist -e "set title 'Sine curve'; plot sin(x)"

   To set user-defined variables a and s prior to executing commands
   from a file:
         gnuplot -e "a=2; s='file.png'" input.gpl












   GNUPLOT 4.1                                                        9


   88..  CCoommmmaanndd--lliinnee--eeddiittiinngg


   Command-line editing and command history are supported using either
   an external gnu readline library, an external BSD libedit library,
   or a built-in equivalent.  This choice is a configuration option at
   the time gnuplot is built.

   The editing commands of the built-in version are given below. The
   gnu readline and BSD libedit libraries have their own documentation.




      +-------------------------------------------------------------+
      |Character   Function                                         |
      +-------------------------------------------------------------+
      |            Line Editing                                     |
      |   ^B       move back a single character.                    |
      |   ^F       move forward a single character.                 |
      |   ^A       move to the beginning of the line.               |
      |   ^E       move to the end of the line.                     |
      | ^H, DEL    delete the previous character.                   |
      |   ^D       delete the current character.                    |
      |   ^K       delete from current position to the end of line. |
      | ^L, ^R     redraw line in case it gets trashed.             |
      |   ^U       delete the entire line.                          |
      |   ^W       delete from the current word to the end of line. |
      +-------------------------------------------------------------+
      |            History                                          |
      |   ^P       move back through history.                       |
      |   ^N       move forward through history.                    |
      +-------------------------------------------------------------+





   99..  CCoommmmeennttss


   Comments are supported as follows: a ## may appear in most places in
   a line and ggnnuupplloott will ignore the rest of the line.  It will not
   have this effect inside quotes, inside numbers (including complex
   numbers), inside command substitutions, etc.  In short, it works
   anywhere it makes sense to work.

   See also sseett ddaattaaffiillee ccoommmmeennttsscchhaarrss for specifying comment charac-
   ters in data files.  Note that if a comment line ends in '\' then
   the subsequent line is also treated as a comment.













   GNUPLOT 4.1                                                       10


   1100..  CCoooorrddiinnaatteess


   The commands sseett aarrrrooww, sseett kkeeyy, sseett llaabbeell and sseett oobbjjeecctt allow you
   to draw something at an arbitrary position on the graph.  This posi-
   tion is specified by the syntax:

         {<system>} <x>, {<system>} <y> {,{<system>} <z>}

   Each <system> can either be ffiirrsstt, sseeccoonndd, ggrraapphh, ssccrreeeenn, or cchhaarraacc--
   tteerr.

   ffiirrsstt places the x, y, or z coordinate in the system defined by the
   left and bottom axes; sseeccoonndd places it in the system defined by the
   second axes (top and right); ggrraapphh specifies the area within the
   axes---0,0 is bottom left and 1,1 is top right (for splot, 0,0,0 is
   bottom left of plotting area; use negative z to get to the
   base---see sseett xxyyppllaannee); ssccrreeeenn specifies the screen area (the
   entire area---not just the portion selected by sseett ssiizzee), with 0,0
   at bottom left and 1,1 at top right; and cchhaarraacctteerr gives the posi-
   tion in character widths and heights from the bottom left of the
   screen area (screen 0,0), cchhaarraacctteerr coordinates depend on the chosen
   font size.

   If the coordinate system for x is not specified, ffiirrsstt is used.  If
   the system for y is not specified, the one used for x is adopted.

   In some cases, the given coordinate is not an absolute position but
   a relative value (e.g., the second position in sseett aarrrrooww ... rrttoo).
   In most cases, the given value serves as difference to the first
   position.  If the given coordinate resides in a logarithmic axis the
   value is interpreted as factor. For example,

         set logscale x
         set arrow 100,5 rto 10,2

   plots an arrow from position 100,5 to position 1000,7 since the x
   axis is logarithmic while the y axis is linear.

   If one (or more) axis is timeseries, the appropriate coordinate
   should be given as a quoted time string according to the ttiimmeeffmmtt
   format string.  See sseett xxddaattaa and sseett ttiimmeeffmmtt.  GGnnuupplloott will also
   accept an integer expression, which will be interpreted as seconds
   from 1 January 2000.



   1111..  DDaattaassttrriinnggss


   Data files may contain string data consisting of either an arbitrary
   string of printable characters containing no whitespace or an arbi-
   trary string of characters, possibly including whitespace, delimited










   GNUPLOT 4.1                                                       11


   by double quotes.  The following sample line from a datafile is
   interpreted to contain four columns, with a text field in column 3:

     1.000 2.000 "Third column is all of this text" 4.00

   Text fields can be positioned within a 2-D or 3-D plot using the
   commands:

     plot 'datafile' using 1:2:4 with labels
     splot 'datafile using 1:2:3:4 with labels

   A column of text data can also be used to label the ticmarks along
   one or more of the plot axes. The example below plots a line through
   a series of points with (X,Y) coordinates taken from columns 3 and 4
   of the input datafile.  However, rather than generating regularly
   spaced tics along the x axis labeled numerically, gnuplot will posi-
   tion a tic mark along the x axis at the X coordinate of each point
   and label the tic mark with text taken from column 1 of the input
   datafile.

     set xtics
     plot 'datafile' using 3:4:xticlabels(1) with linespoints

   There is also an option that will interpret the first entry in a
   column of input data (i.e. the column heading) as a text field, and
   use it as the key title for data plotted from that column. The exam-
   ple given below will use the first entry in column 2 to generate a
   title in the key box, while processing the remainder of columns 2
   and 4 to draw the required line:

     plot 'datafile' using 1:(f($2)/$4) with lines title columnhead(2)

   Another example:

     plot for [i=2:6] 'datafile' using i title "Results for ".column-
   head(i)

   See sseett ssttyyllee llaabbeellss, uussiinngg xxttiiccllaabbeellss, pplloott ttiittllee, uussiinngg.



   1122..  EEnnhhaanncceedd tteexxtt mmooddee


   Many terminal types support an enhanced text mode in which addi-
   tional formatting information is embedded in the text string.  For
   example, "x^2" will write x-squared as we are used to seeing it,
   with a superscript 2.  This mode is normally selected when you set
   the terminal, e.g.  "set term png enhanced", but may also be toggled
   afterward using "set termoption enhanced", or by marking individual
   strings as in "set label 'x_2' noenhanced".












   GNUPLOT 4.1                                                       12


        +--------------------------------------------------------+
        |.lf 817  _C_o_n_tc_re_on_ltEexramb_cpo_clx_le.st_Ea_xb_p_l(_a)_n;_a_t_i_o_n        ..._n_n_n_r_r_r333_b_b_b_o_o_o_t_t_t_8_8_8_0_0_0>>>???_8_8_8_0_0_0...|_s_s_s_p_p_p|||_8_1_2_0_6_0_u_0_0._u_u3.._r33_v_r_r_p_v_v_t_p_p1_t_t.11_s.._p_s_s|_p_p_8||_0_8_8_u_0_0._u_u_n.._r_n_n3_r_r_b33_r_b_b_u_r_r_l_u_u_e_l_l1_e_e.113.._r3_v_e_r_s_l_e2_e_l_p_a_e>_s_a?_e_s_4._e_03._u_k3._e_k_l_e_e_s_p_e1._p3._r3_m_r_k_m3_k_r3_t_r1_t.2_n._r_n3_r_c3_r_c_o_r_w_o1_w.23._k3_e_k_e_e_p_e._p_m._k_m3_k_r3_s_r1_s.2_m._k_m3_k_b3_o_b_t_o._t3._r3_v_r_p_v_t_p0_t.0_t._a_t_1_a_0_1_3_0_2_3_u_2._u_l._f_l7_f37132
        |    & inserts space of specified length                 |
        | ~ _a.8-overprints '-' on 'a', raised by .8              |
        |         times the current fontsize                     |
        +--------------------------------------------------------+



   Braces can be used to place multiple-character text where a single
   character is expected (e.g., 2^{10}).  To change the font and/or
   size, use the full form: {/[fontname][=fontsize | *fontscale] text}.
   Thus {/Symbol=20 G} is a 20 pt GAMMA and {/*0.75 K} is a K at three-
   quarters of whatever fontsize is currently in effect.  (The '/'
   character MUST be the first character after the '{'.)

   The phantom box is useful for a@^b_c to align superscripts and sub-
   scripts but does not work well for overwriting an accent on a let-
   ter.  For the latter, it is much better to use an encoding  (e.g.
   iso_8859_1 or utf8) that contains a large variety of letters with
   accents or other diacritical marks.  See sseett eennccooddiinngg. Since the box
   is non-spacing, it is sensible to put the shorter of the subscript
   or superscript in the box (that is, after the @).

   Space equal in length to a string can be inserted using the '&'
   character.  Thus
           'abc&{def}ghi'
   would produce
           'abc   ghi'.

   The '~' character causes the next character or bracketed text to be
   overprinted by the following character or bracketed text.  The sec-
   ond text will be horizontally centered on the first.  Thus '~a/'
   will result in an 'a' with a slash through it.  You can also shift
   the second text vertically by preceding the second text with a num-
   ber, which will define the fraction of the current fontsize by which
   the text will be raised or lowered.  In this case the number and
   text must be enclosed in brackets because more than one character is
   necessary.  If the overprinted text begins with a number, put a
   space between the vertical offset and the text ('~{abc}{.5 000}');
   otherwise no space is needed ('~{abc}{.5---}').  You can change the
   font for one or both strings ('~a{.5 /*.2 o}'---an 'a' with a one-
   fifth-size 'o' on top---and the space between the number and the
   slash is necessary), but you can't change it after the beginning of
   the string.  Neither can you use any other special syntax within
   either string.  You can, of course, use control characters by escap-
   ing them (see below), such as '~a{\^}'

   You can access special symbols numerically by specifying \character-
   code (in octal), e.g., {/Symbol \245} is the symbol for infinity.
   This does not work for multibyte encodings like UTF-8, however.  In
   a UTF-8 environment, you should be able to enter multibyte sequences
   implicitly by typing or otherwise selecting the character you want.










   GNUPLOT 4.1                                                       13


   You can escape control characters using \, e.g.,  \\, \{, and so on.

   But be aware that strings in double-quotes are parsed differently
   than those enclosed in single-quotes.  The major difference is that
   backslashes may need to be doubled when in double-quoted strings.

   Examples (these are hard to describe in words---try them!):
         set xlabel 'Time (10^6 {/Symbol m}s)'
         set title '{/Symbol=18 \\362@_{/=9.6 0}^{/=12 x}} \\
                    {/Helvetica e^{-{/Symbol m}^2/2} d}{/Symbol m}'

   The file "ps_guide.ps" in the /docs/psdoc subdirectory of the gnu-
   plot source distribution contains more examples of the enhanced syn-
   tax.



   1133..  EEnnvviirroonnmmeenntt


   A number of shell environment variables are understood by ggnnuupplloott.
   None of these are required, but may be useful.

   If GNUTERM is defined, it is used as the name of the terminal type
   to be used.  This overrides any terminal type sensed by ggnnuupplloott on
   start-up, but is itself overridden by the .gnuplot (or equivalent)
   start-up file (see ssttaarrtt--uupp) and, of course, by later explicit
   changes.

   GNUHELP may be defined to be the pathname of the HELP file (gnu-
   plot.gih).

   On VMS, the logical name GNUPLOT$HELP should be defined as the name
   of the help library for ggnnuupplloott.  The ggnnuupplloott help can be put inside
   any system help library, allowing access to help from both within
   and outside ggnnuupplloott if desired.

   On Unix, HOME is used as the name of a directory to search for a
   .gnuplot file if none is found in the current directory.  On Ami-
   gaOS, MS-DOS, Windows and OS/2, GNUPLOT is used.  On Windows, the
   NT-specific variable USERPROFILE is tried, too. VMS, SYS$LOGIN: is
   used. Type hheellpp ssttaarrtt--uupp.

   On Unix, PAGER is used as an output filter for help messages.

   On Unix and AmigaOS, SHELL is used for the sshheellll command.  On MS-DOS
   and OS/2, COMSPEC is used for the sshheellll command.

   FIT_SCRIPT may be used to specify a ggnnuupplloott command to be executed
   when a fit is interrupted---see ffiitt.  FIT_LOG specifies the default
   filename of the logfile maintained by fit.

   GNUPLOT_LIB may be used to define additional search directories for










   GNUPLOT 4.1                                                       14


   data and command files. The variable may contain a single directory
   name, or a list of directories separated by a platform-specific path
   separator, eg. ':' on Unix, or ';' on DOS/Windows/OS/2/Amiga plat-
   forms. The contents of GNUPLOT_LIB are appended to the llooaaddppaatthh
   variable, but not saved with the ssaavvee and ssaavvee sseett commands.

   Several gnuplot terminal drivers access TrueType fonts via the gd
   library.  For these drivers the font search path is controlled by
   the environmental variable GDFONTPATH.  Furthermore, a default font
   for these drivers may be set via the environmental variable GNU-
   PLOT_DEFAULT_GDFONT.

   The postscript terminal uses its own font search path. It is con-
   trolled by the environmental variable GNUPLOT_FONTPATH. The format
   is the same as for GNUPLOT_LIB. The contents of GNUPLOT_FONTPATH are
   appended to the ffoonnttppaatthh variable, but not saved with the ssaavvee and
   ssaavvee sseett commands.

   GNUPLOT_PS_DIR is used by the postscript driver to use external pro-
   logue files. Depending on the build process, gnuplot contains either
   a builtin copy of those files or simply a default hardcoded path.
   Use this variable to test the postscript terminal with custom pro-
   logue files. See ppoossttssccrriipptt pprroolloogguuee.



   1144..  EExxpprreessssiioonnss


   In general, any mathematical expression accepted by C, FORTRAN, Pas-
   cal, or BASIC is valid.  The precedence of these operators is deter-
   mined by the specifications of the C programming language.  White
   space (spaces and tabs) is ignored inside expressions.

   Complex constants are expressed as {<real>,<imag>}, where <real> and
   <imag> must be numerical constants.  For example, {3,2} represents 3
   + 2i; {0,1} represents 'i' itself.  The curly braces are explicitly
   required here.

   Note that gnuplot uses both "real" and "integer" arithmetic, like
   FORTRAN and C.  Integers are entered as "1", "-10", etc; reals as
   "1.0", "-10.0", "1e1", 3.5e-1, etc.  The most important difference
   between the two forms is in division: division of integers trun-
   cates: 5/2 = 2; division of reals does not: 5.0/2.0 = 2.5.  In mixed
   expressions, integers are "promoted" to reals before evaluation:
   5/2e0 = 2.5.  The result of division of a negative integer by a pos-
   itive one may vary among compilers.  Try a test like "print -5/2" to
   determine if your system chooses -2 or -3 as the answer.

   The integer expression "1/0" may be used to generate an "undefined"
   flag, which causes a point to ignored; the tteerrnnaarryy operator gives an
   example.  Or you can use the pre-defined variable NaN to achieve the
   same result.










   GNUPLOT 4.1                                                       15


   The real and imaginary parts of complex expressions are always real,
   whatever the form in which they are entered: in {3,2} the "3" and
   "2" are reals, not integers.

   Gnuplot can also perform simple operations on strings and string
   variables.  For example, the expression ("A" . "B" eq "AB") evalu-
   ates as true, illustrating the string concatenation operator and the
   string equality operator.

   A string which contains a numerical value is promoted to the corre-
   sponding integer or real value if used in a numerical expression.
   Thus ("3" + "4" == 7) and (6.78 == "6.78") both evaluate to true.
   An integer, but not a real or complex value, is promoted to a string
   if used in string concatenation.  A typical case is the use of inte-
   gers to construct file names or other strings; e.g. ("file" . 4 eq
   "file4") is true.

   Substrings can be specified using a postfixed range descriptor
   [beg:end].  For example, "ABCDEF"[3:4] == "CD"   and   "ABCDEF"[4:*]
   == "DEF" The syntax "string"[beg:end] is exactly equivalent to call-
   ing the built-in string-valued function substr("string",beg,end),
   except that you cannot omit either beg or end from the function
   call.




        1144..11..  FFuunnccttiioonnss


        The functions in ggnnuupplloott are the same as the corresponding
        functions in the Unix math library, except that all functions
        accept integer, real, and complex arguments, unless otherwise
        noted.

        For those functions that accept or return angles that may be
        given in either degrees or radians (sin(x), cos(x), tan(x),
        asin(x), acos(x), atan(x), atan2(x) and arg(z)), the unit may
        be selected by sseett aanngglleess, which defaults to radians.
























   GNUPLOT 4.1                                                       16


   +---------------------------------------------------------------------------------------------------+
   |   Function                Arguments            Returns                                            |
   +---------------------------------------------------------------------------------------------------+
   |    abs(x)                    any               absolute value of _x, |_x|; same type                |
   |    abs(x)                  complex             length of _x, real(_x)2+imag(_x)2                     |
   |    acos(x)                   any               cos-1_x (inverse cosine)                            |
   |   acosh(x)                   any               cosh-1_x (inverse hyperbolic cosine) in radians     |
   |    arg(x)                  complex             the phase of _x                                     |
   |    asin(x)                   any               sin-1_x (inverse sin)                               |
   |   asinh(x)                   any               sinh-1_x (inverse hyperbolic sin) in radians        |
   |    atan(x)                   any               tan-1_x (inverse tangent)                           |
   |  atan2(y,x)              int or real           tan-1(_y/_x) (inverse tangent)                       |
   |   atanh(x)                   any               tanh-1_x (inverse hyperbolic tangent) in radians    |
   | EllipticK(k)          real k in (-1:1)         _K_k complete elliptic integral of the first kind    |
   | EllipticE(k)          real k in [-1:1]          _E_k complete elliptic integral of the second kind  |
   |EllipticPi(n,k)    real n<1, real k in (-1:1)    _n,_k complete elliptic integral of the third kind  |
   |   besj0(x)               int or real           _j0 Bessel function of _x, in radians                |
   |   besj1(x)               int or real           _j1 Bessel function of _x, in radians                |
   |   besy0(x)               int or real           _y0 Bessel function of _x, in radians                |
   |   besy1(x)               int or real           _y1 Bessel function of _x, in radians                |
   |    ceil(x)                   any               _x, smallest integer not less than _x (real part)    |
   |    cos(x)                  radians             cos_x, cosine of _x                                  |
   |    cosh(x)                   any               cosh_x, hyperbolic cosine of _x in radians           |
   |    erf(x)                    any               _e_r_f(real(_x)), error function of real (_x)           |
   |    erfc(x)                   any               _e_r_f_c(real(_x)), 1.0 - error function of real (_x)    |
   |    exp(x)                    any               _e_x, exponential function of _x                      |
   |   floor(x)                   any               _x, largest integer not greater than _x (real part)  |
   |   gamma(x)                   any               (real(_x)), gamma function of real (_x)              |
   | ibeta(p,q,x)                 any               _i_b_e_t_a(real(_p,_q,_x)), ibeta function of real (_p,_q,_x) |
   |   inverf(x)                  any               inverse error function real(_x)                     |
   |  igamma(a,x)                 any               _i_g_a_m_m_a(real(_a,_x)), igamma function of real (_a,_x)   |
   |    imag(x)                 complex             imaginary part of _x as a real number               |
   |  invnorm(x)                  any               inverse normal distribution function real(_x)       |
   |    int(x)                   real               integer part of _x, truncated toward zero           |
   |  lambertw(x)                real               Lambert W function                                 |
   |   lgamma(x)                  any               _l_g_a_m_m_a(real(_x)), lgamma function of real (_x)       |
   |    log(x)                    any               ln_x, natural logarithm (base _e) of _x               |
   |   log10(x)                   any               log10_x, logarithm (base 10) of _x                   |
   |    norm(x)                   any               _n_o_r_m(_x), normal distribution function of real(_x)   |
   |    rand(x)                   any               _r_a_n_d(_x), pseudo random number generator            |
   |    real(x)                   any               real part of _x                                     |
   |    sgn(x)                    any               1 if _x>0, -1 if _x<0, 0 if _x=0. imag(_x) ignored     |
   |    sin(x)                    any               sin_x, sine of _x                                    |
   |    sinh(x)                   any               sinh_x, hyperbolic sine of _x in radians             |
   |    sqrt(x)                   any               _x, square root of _x                                |
   |    tan(x)                    any               tan_x, tangent of _x                                 |
   |    tanh(x)                   any               tanh_x, hyperbolic tangent of _x in radians          |
   +---------------------------------------------------------------------------------------------------+















   GNUPLOT 4.1                                                       17


   +---------------------------------------------------------------------------------------------+
   |        Function            Arguments    Returns                                             |
   +---------------------------------------------------------------------------------------------+
   |  gprintf("format",x)          any       string result from applying gnuplot's format parser |
   |sprintf("format",x,...)     multiple     string result from C-language sprintf               |
   |    strlen("string")         string      int length of string                                |
   |strstrt("string","key")      strings     int index of first character of substring "key"     |
   |substr("string",beg,end)    multiple     string "string"[beg:end]                            |
   |strftime("timeformat",t)       any       string result from applying gnuplot's time parser   |
   |strptime("timeformat",s)     string      seconds since year 2000 as given in string s        |
   |   system("command")         string      stdout containing output stream of shell command    |
   |    word("string",n)       string, int   returns the nth word in "string"                    |
   |    words("string")          string      returns the number of words in "string"             |
   +---------------------------------------------------------------------------------------------+






   +--------------------------------------------------------------------------------------------+
   |   Function         Arguments     Returns                                                   |
   +--------------------------------------------------------------------------------------------+
   |   column(x)           int         column _x during datafile manipulation.                   |
   | columnhead(x)         int         string containing first entry of column _x in datafile.   |
   |  defined(X)      variable name    [DEPRECATED] returns 1 if X is defined, 0 otherwise.     |
   |  exists("X")        string        returns 1 if a variable named X is defined, 0 otherwise. |
   |stringcolumn(x)        int         content column _x as a string.                            |
   | timecolumn(x)         int         timecolumn _x during datafile manipulation.               |
   |  tm_hour(x)           int        the hour                                                  |
   |  tm_mday(x)           int        the day of the month                                      |
   |   tm_min(x)           int        the minute                                                |
   |   tm_mon(x)           int        the month                                                 |
   |   tm_sec(x)           int        the second                                                |
   |  tm_wday(x)           int        the day of the week                                       |
   |  tm_yday(x)           int        the day of the year                                       |
   |  tm_year(x)           int        the year                                                  |
   |   valid(x)            int         test validity of column(_x) during datafile manip.        |
   | value("name")       string        returns the current value of the named variable.         |
   +--------------------------------------------------------------------------------------------+







             1144..11..11..  EElllliippttiicc iinntteeggrraallss


             The EElllliippttiiccKK((kk)) function returns the complete elliptic
             integral of the first kind, i.e. the definite integral
             between 0 and pi/2 of the function










   GNUPLOT 4.1                                                       18


             ((11--((kk**ssiinn((pp))))****22))****((--00..55)).  The domain of kk is -1 to 1
             (exclusive).

             The EElllliippttiiccEE((kk)) function returns the complete elliptic
             integral of the second kind, i.e. the definite integral
             between 0 and pi/2 of the function ((11--((kk**ssiinn((pp))))****22))****00..55.
             The domain of kk is -1 to 1 (inclusive).

             The EElllliippttiiccPPii((nn,,kk)) function returns the complete elliptic
             integral of the third kind, i.e. the definite integral
             between 0 and pi/2 of the function
             ((11--((kk**ssiinn((pp))))****22))****((--00..55))//((11--nn**ssiinn((pp))****22)).  The parameter
             nn must be less than 1, while kk must lie between -1 and 1
             (exclusive).  Note that by definition EllipticPi(0,k) ==
             EllipticK(k) for all possible values of kk.



             1144..11..22..  RRaannddoomm nnuummbbeerr ggeenneerraattoorr


             Some older versions of gnuplot used rand(x>0) to produce
             sequential pseudo-random numbers.  The current behavior is
             as follows:
              `rand(0)`  returns a pseudo random number in the interval
             [0:1] generated
                         from the current value of two internal 32-bit
             seeds.
              `rand(-1)` resets both seeds to a standard value.
              `rand(x)`  for x>0 sets both seeds to a value based on
             the value of x.
              `rand({x,y})` for x>0 sets seed1 to x and seed2 to y.




             1144..11..33..  VVaalluuee


             B = value("A") is effectively the same as B = A, where A
             is the name of a user-defined variable.  This is useful
             when the name of the variable is itself held in a string
             variable. See uusseerr--ddeeffiinneedd vvaarriiaabblleess.  It also allows you
             to read the name of a variable from a data file.  If the
             argument is a numerical expression, value() returns the
             value of that expression.  If the argument is a string
             that does not correspond to a currently defined variable,
             value() returns NaN.















   GNUPLOT 4.1                                                       19


        1144..22..  OOppeerraattoorrss


        The operators in ggnnuupplloott are the same as the corresponding
        operators in the C programming language, except that all opera-
        tors accept integer, real, and complex arguments, unless other-
        wise noted.  The ** operator (exponentiation) is supported, as
        in FORTRAN.

        Parentheses may be used to change order of evaluation.




             1144..22..11..  UUnnaarryy


             The following is a list of all the unary operators and
             their usages:







    +-----------------------------------------------------------------+
    |Symbol   Example   Explanation                                   |
    +-----------------------------------------------------------------+
    |  -        -a      unary minus                                   |
    |  +        +a      unary plus (no-operation)                     |
    |  ~        ~a      * one's complement                            |
    |  !        !a      * logical negation                            |
    |  !        a!      * factorial                                   |
    |  $        $3      * call arg/column during `using` manipulation |
    +-----------------------------------------------------------------+
    +-----------------------------------------------------------------+


   (*) Starred explanations indicate that the operator requires an
   integer argument.

   Operator precedence is the same as in Fortran and C.  As in those
   languages, parentheses may be used to change the order of operation.
   Thus -2**2 = -4, but (-2)**2 = 4.

   The factorial operator returns a real number to allow a greater
   range.















   GNUPLOT 4.1                                                       20


             1144..22..22..  BBiinnaarryy


             The following is a list of all the binary operators and
             their usages:




              +--------------------------------------------+
              |Symbol   Example   Explanation              |
              +--------------------------------------------+
              |  **      a**b     exponentiation           |
              |  *        a*b     multiplication           |
              |  /        a/b     division                 |
              |  %        a%b     * modulo                 |
              |  +        a+b     addition                 |
              |  -        a-b     subtraction              |
              |  ==      a==b     equality                 |
              |  !=      a!=b     inequality               |
              |  <        a<b     less than                |
              |  <=      a<=b     less than or equal to    |
              |  >        a>b     greater than             |
              |  >=      a>=b     greater than or equal to |
              |  &        a&b     * bitwise AND            |
              |  ^        a^b     * bitwise exclusive OR   |
              |  |        a|b     * bitwise inclusive OR   |
              |  &&      a&&b     * logical AND            |
              |  ||      a||b     * logical OR             |
              +--------  a = b    assignment               |
              |  ,       (a,b)    serial evaluation        |
              |  eq     A eq B    string equality          |
              |  ne     A ne B    string inequality        |
              +--------------------------------------------+


   (*) Starred explanations indicate that the operator requires integer
   arguments.  Capital letters A and B indicate that the operator
   requires string arguments.

   Logical AND (&&) and OR (||) short-circuit the way they do in C.
   That is, the second &&&& operand is not evaluated if the first is
   false; the second |||| operand is not evaluated if the first is true.

   Serial evaluation occurs only in parentheses and is guaranteed to
   proceed in left to right order.  The value of the rightmost subex-
   pression is returned.
















   GNUPLOT 4.1                                                       21


             1144..22..33..  TTeerrnnaarryy


             There is a single ternary operator:




                 +---------------------------------------+
                 |Symbol   Example   Explanation         |
                 +---------------------------------------+
                 |  ?:      a?b:c    * ternary operation |
                 +---------------------------------------+


   The ternary operator behaves as it does in C.  The first argument
   (a), which must be an integer, is evaluated.  If it is true (non-
   zero), the second argument (b) is evaluated and returned; otherwise
   the third argument (c) is evaluated and returned.

   The ternary operator is very useful both in constructing piecewise
   functions and in plotting points only when certain conditions are
   met.

   Examples:

   Plot a function that is to equal sin(x) for 0 <= x < 1, 1/x for 1 <=
   x < 2, and undefined elsewhere:
         f(x) = 0<=x && x<1 ? sin(x) : 1<=x && x<2 ? 1/x : 1/0
         plot f(x)
   Note that ggnnuupplloott quietly ignores undefined values, so the final
   branch of the function (1/0) will produce no plottable points.  Note
   also that f(x) will be plotted as a continuous function across the
   discontinuity if a line style is used.  To plot it discontinuously,
   create separate functions for the two pieces.  (Parametric functions
   are also useful for this purpose.)

   For data in a file, plot the average of the data in columns 2 and 3
   against the datum in column 1, but only if the datum in column 4 is
   non-negative:

         plot 'file' using 1:( $4<0 ? 1/0 : ($2+$3)/2 )

   For an explanation of the uussiinngg syntax, please see pplloott ddaattaaffiillee
   uussiinngg.




        1144..33..  GGnnuupplloott--ddeeffiinneedd vvaarriiaabblleess













   GNUPLOT 4.1                                                       22


        Gnuplot maintains a number of read-only variables that reflect
        the current internal state of the program and the most recent
        plot. These variables begin with the prefix "GPVAL_".  Examples
        include GPVAL_TERM, GPVAL_X_MIN, GPVAL_X_MAX, GPVAL_Y_MIN.
        Type sshhooww vvaarriiaabblleess aallll to display the complete list and cur-
        rent values.  Values related to axes parameters (ranges, log
        base) are values used during the last plot, not those currently
        sseett.

        The read-only variable GPVAL_ERRNO is set to a non-zero value
        if any gnuplot command terminates early due to an error.  The
        most recent error message is stored in the string variable
        GPVAL_ERRMSG.  Both GPVAL_ERRNO and GPVAL_ERRMSG can be cleared
        using the command rreesseett eerrrroorrss.

        Interactive terminals with mmoouussee functionality maintain read-
        only variables with the prefix "MOUSE_".  See mmoouussee vvaarriiaabblleess
        for details.

        The ffiitt mechanism uses several variables with names that begin
        "FIT_".  It is safest to avoid using such names.  "FIT_LIMIT",
        however, is one that you may wish to redefine. Under sseett ffiitt
        eerrrroorrvvaarriiaabblleess, the error for each fitted parameter will be
        stored in a variable named like the parameter, but with "_err"
        appended. See the documentation on ffiitt for details.

        See uusseerr--ddeeffiinneedd vvaarriiaabblleess, rreesseett eerrrroorrss, mmoouussee vvaarriiaabblleess, and
        ffiitt.




        1144..44..  UUsseerr--ddeeffiinneedd vvaarriiaabblleess aanndd ffuunnccttiioonnss


        New user-defined variables and functions of one through twelve
        variables may be declared and used anywhere, including on the
        pplloott command itself.

        User-defined function syntax:
              <func-name>( <dummy1> {,<dummy2>} ... {,<dummy12>} ) =
        <expression>

        where <expression> is defined in terms of <dummy1> through
        <dummy12>.

        User-defined variable syntax:
              <variable-name> = <constant-expression>

        Examples:
              w = 2
              q = floor(tan(pi/2 - 0.1))
              f(x) = sin(w*x)










   GNUPLOT 4.1                                                       23


              sinc(x) = sin(pi*x)/(pi*x)
              delta(t) = (t == 0)
              ramp(t) = (t > 0) ? t : 0
              min(a,b) = (a < b) ? a : b
              comb(n,k) = n!/(k!*(n-k)!)
              len3d(x,y,z) = sqrt(x*x+y*y+z*z)
              plot f(x) = sin(x*a), a = 0.2, f(x), a = 0.4, f(x)

              file = "mydata.inp"
              file(n) = sprintf("run_%d.dat",n)

        The final two examples illustrate a user-defined string vari-
        able and a user-defined string function.

        Note that the variables ppii (3.14159...) and NNaaNN (IEEE "Not a
        Number") are already defined.  You can redefine these to some-
        thing else if you really need to. The original values can be
        recovered by setting:

              NaN = GPVAL_NaN
              pi  = GPVAL_pi

        Other variables may be defined under various gnuplot operations
        like mousing in interactive terminals or fitting; see ggnnuupplloott--
        ddeeffiinneedd vvaarriiaabblleess for details.

        You can check for existence of a given variable V by the
        exists("V") expression. For example
              a = 10
              if (exists("a")) print "a is defined"
              if (!exists("b")) print "b is not defined"

        Valid names are the same as in most programming languages: they
        must begin with a letter, but subsequent characters may be let-
        ters, digits, or "_".

        Each function definition is made available as a special string-
        valued variable with the prefix 'GPFUN_'.

        Example:
              set label GPFUN_sinc at graph .05,.95

        See sshhooww ffuunnccttiioonnss, ffuunnccttiioonnss, ggnnuupplloott--ddeeffiinneedd vvaarriiaabblleess,
        mmaaccrrooss, vvaalluuee.



   1155..  FFoonnttss


   Gnuplot does not provide any fonts of its own. It relies on external
   font handling, the details of which unfortunately vary from one ter-
   minal type to another. Brief documentation of font mechanisms that










   GNUPLOT 4.1                                                       24


   apply to more than one terminal type is given here. For information
   on font use by other individual terminals, see the documentation for
   that terminal.




        1155..11..  CCaaiirroo ((ppddffccaaiirroo,, ppnnggccaaiirroo,, wwxxtt tteerrmmiinnaallss))


        Sorry, this section is under construction.  These terminals
        find and access fonts using the external fontconfig tool set.
        Please see the fontconfig user manual.  It is usually suffi-
        cient in gnuplot to request a font by a generic name and size,
        letting fontconfig substitute a similar font if necessary. The
        following will probably all work:
             set term pdfcairo font "sans,12"
             set term pdfcairo font "Times,12"
             set term pdfcairo font "Times-New-Roman,12"




        1155..22..  GGdd ((ppnngg,, ggiiff,, jjppeegg tteerrmmiinnaallss))


        Font handling for the png, gif, and jpeg terminals is done by
        the external library libgd.  Five basic fonts are provided
        directly by libgd. These are ttiinnyy (5x8 pixels), ssmmaallll (6x12
        pixels), mmeeddiiuumm, (7x13 Bold), llaarrggee (8x16) or ggiiaanntt (9x15 pix-
        els). These fonts cannot be scaled or rotated.  Use one of
        these keywords instead of the ffoonntt keyword. E.g.
             set term png tiny

        On most systems libgd also provides access to Adobe Type 1
        fonts (*.pfa) and TrueType fonts (*.ttf). You must give the
        name of the font file, not the name of the font inside it, in
        the form "<face> {,<pointsize>}".  <face> is either the full
        pathname to the font file, or the first part of a filename in
        one of the directories listed in the GDFONTPATH environmental
        variable. That is, 'set term png font "Face"' will look for a
        font file named either <somedirectory>/Face.ttf or <somedirec-
        tory>/Face.pfa.  For example, if GDFONTPATH contains
        //uussrr//llooccaall//ffoonnttss//ttttff:://uussrr//llooccaall//ffoonnttss//ppffaa then the following
        pairs of commands are equivalent
             set term png font "arial"
             set term png font "/usr/local/fonts/ttf/arial.ttf"
             set term png font "Helvetica"
             set term png font "/usr/local/fonts/pfa/Helvetica.pfa"
        To request a default font size at the same time:
             set term png font "arial,11"

        Both TrueType and Adobe Type 1 fonts are fully scalable and










   GNUPLOT 4.1                                                       25


        rotatable.  If no specific font is requested in the "set term"
        command, gnuplot checks the environmental variable GNU-
        PLOT_DEFAULT_GDFONT to see if there is a preferred default
        font.



        1155..33..  PPoossttssccrriipptt  ((aallssoo eennccaappssuullaatteedd ppoossttssccrriipptt **..eeppss))


        PostScript font handling is done by the printer or viewing pro-
        gram.  Gnuplot can create valid PostScript or encapsulated
        PostScript (*.eps) even if no fonts at all are installed on
        your computer.  Gnuplot simply refers to the font by name in
        the output file, and assumes that the printer or viewing pro-
        gram will know how to find or approximate a font by that name.

        All PostScript printers or viewers should know about the stan-
        dard set of Adobe fonts TTiimmeess--RRoommaann, HHeellvveettiiccaa, CCoouurriieerr, and
        SSyymmbbooll.  It is likely that many additional fonts are also
        available, but the specific set depends on your system or
        printer configuration. Gnuplot does not know or care about
        this; the output *.ps or *.eps files that it creates will sim-
        ply refer to whatever font names you request.

        Thus
             set term postscript eps font "Times-Roman,12"
        will produce output that is suitable for all printers and view-
        ers.

        On the other hand
             set term postscript eps font "Garamond-Premier-Pro-Italic"
        will produce an output file that contains valid PostScript, but
        since it refers to a specialized font, only some printers or
        viewers will be able to display the specific font that was
        requested.  Most will substitute a different font.

        However, it is possible to embed a specific font in the output
        file so that all printers will be able to use it. This requires
        that the a suitable font description file is available on your
        system. Note that some font files require specific licensing if
        they are to be embedded in this way.  See ppoossttssccrriipptt ffoonnttffiillee
        for more detailed description and examples.



   1166..  GGlloossssaarryy


   Throughout this document an attempt has been made to maintain con-
   sistency of nomenclature.  This cannot be wholly successful because
   as ggnnuupplloott has evolved over time, certain command and keyword names
   have been adopted that preclude such perfection.  This section










   GNUPLOT 4.1                                                       26


   contains explanations of the way some of these terms are used.

   A "page" or "screen" or "canvas" is the entire area addressable by
   ggnnuupplloott.  On a desktop it is a full window; on a plotter, it is a
   single sheet of paper; in svga mode it is the full monitor screen.

   A screen may contain one or more "plots".  A plot is defined by an
   abscissa and an ordinate, although these need not actually appear on
   it, as well as the margins and any text written therein.

   A plot contains one "graph".  A graph is defined by an abscissa and
   an ordinate, although these need not actually appear on it.

   A graph may contain one or more "lines".  A line is a single func-
   tion or data set.  "Line" is also a plotting style.  The word will
   also be used in sense "a line of text".  Presumably the context will
   remove any ambiguity.

   The lines on a graph may have individual names.  These may be listed
   together with a sample of the plotting style used to represent them
   in the "key", sometimes also called the "legend".

   The word "title" occurs with multiple meanings in ggnnuupplloott.  In this
   document, it will always be preceded by the adjective "plot",
   "line", or "key" to differentiate among them.  A 2D graph may have
   up to four labelled aaxxeess.  The names of the four axes are "x" for
   the axis along the bottom border of the plot, "y" for the axis along
   the left border, "x2" for the top border, and "y2" for the right
   border.  See aaxxeess.

   A 3D graph may have up to three labelled aaxxeess -- "x", "y" and "z".
   It is not possible to say where on the graph any particular axis
   will fall because you can change the direction from which the graph
   is seen with sseett vviieeww.

   When discussing data files, the term "record" will be resurrected
   and used to denote a single line of text in the file, that is, the
   characters between newline or end-of-record characters.  A "point"
   is the datum extracted from a single record.  A "datablock" is a set
   of points from consecutive records, delimited by blank records.  A
   line, when referred to in the context of a data file, is a subset of
   a datablock.



   1177..  LLiinneettyyppee,, ccoolloorrss,, aanndd ssttyylleess


   Each gnuplot terminal type provides a set of distinct "linetypes".
   These may differ in color, in thickness, in dot/dash pattern, or in
   some combination of color and dot/dash. The default linetypes for a
   particular terminal can be previewed by issuing the tteesstt command
   after setting the terminal type.  The pre-defined colors and










   GNUPLOT 4.1                                                       27


   dot/dash patterns are not guaranteed to be consistent for all termi-
   nal types, but all terminals use the special linetype -1 to mean a
   solid line in the primary foreground color (normally black).  By
   default, successive functions or datafiles plotted by a single com-
   mand will be assigned successive linetypes.  You can override this
   default by specifying a particular linetype for any function,
   datafile, or plot element.

   Examples:

        plot "foo", "bar"                 # plot two files using line-
   types 1, 2
        plot sin(x) linetype 4            # terminal-specific linetype
   color 4
        plot sin(x) lt -1                 # black

   For many terminal types it is also possible to assign user-defined
   colors using explicit rgb (red, green, blue) values, named colors,
   or color values that refer to the current pm3d palette.

   Examples:

        plot sin(x) lt rgb "violet"       # one of gnuplot's named col-
   ors
        plot sin(x) lt rgb "#FF00FF"      # explicit RGB triple in
   hexadecimal
        plot sin(x) lt palette cb -45     # whatever color corresponds
   to -45
                                          # in the current cbrange of
   the palette
        plot sin(x) lt palette frac 0.3   # fractional value along the
   palette

   See sshhooww ccoolloorrnnaammeess, sseett ppaalleettttee, ccbbrraannggee.

   For terminals that support dot/dash patterns, each default linetype
   has both a dot-dash pattern and a default color. However, you can
   override the default color by using the keyword lliinneeccoolloorr, abbrevi-
   ated llcc.  For example, the postscript terminal provides a dashed
   blue line as linetype 3.  The plot commands below use this same dash
   pattern for three plots, one in blue (the default), another in red
   (the default for linetype 1), and a third in gold.

   Example:

        set term postscript dashed color
        plot 'foo' lt 3, 'baz' lt 3 linecolor 1, 'bar' lt 3 lc rgb
   'gold'

   Lines can have additional properties such as linewidth.  You can as-
   sociate these various properties, as well as equivalent properties
   for point symbols, into user-defined "line styles" using the command
   sseett ssttyyllee lliinnee.  Once you have defined a linestyle, you can use it










   GNUPLOT 4.1                                                       28


   in a plot command to control the appearance of one or more plot ele-
   ments.

   Examples:

        # define a new line style with terminal-independent color cyan,
        # linewidth 3, and associated point type 6 (a circle with a dot
   in it).
        set style line 5 lt rgb "cyan" lw 3 pt 6
        plot sin(x) with linespoints ls 5          # user-defined line
   style 5

   See lliinneessttyyllee, sseett ssttyyllee lliinnee.




        1177..11..  CCoolloorrssppeecc


        Many commands allow you to specify a linetype with an explicit
        color.  Terminal-independent color choice is only possible for
        terminals that support RGB color or pm3d palettes.

        Syntax:

              ... {linecolor | lc} {<colorspec> | <n>}
              ... {textcolor | tc} {<colorspec> | {linetype | lt} <n>}

        where <colorspec> has one of the following forms:

              rgbcolor "colorname"
              rgbcolor "#RRGGBB"
              rgbcolor variable       # color is read from input file
              palette frac <val>      # <val> runs from 0 to 1
              palette cb <value>      # <val> lies within cbrange
              palette z
              variable                # color index is read from input
        file

        The "<n>" is the linetype number the color of which is used,
        see tteesstt.

        "colorname" refers to one of the color names built in to gnu-
        plot. For a list of the available names, see sshhooww ccoolloorrnnaammeess.

        "#RRGGBB" is a hexadecimal constant preceded by the "#" symbol.
        The RRGGBB represents the red, green, and blue components of
        the color, each on a scale from 0 - 255.  For example, magenta
        = full-scale red + full-scale blue would be represented by
        #FF00FF, which is the hexadecimal representation of (255 << 16)
        + (0 << 8) + (255).











   GNUPLOT 4.1                                                       29


        The color palette is a linear gradient of colors that smoothly
        maps a single numerical value onto a particular color.  Two
        such mappings are always in effect. ppaalleettttee ffrraacc  maps a frac-
        tional value between 0 and 1 onto the full range of the color
        palette.  ppaalleettttee ccbb maps the range of the color axis onto the
        same palette.  See sseett ccbbrraannggee.  See also sseett ccoolloorrbbooxx.  You
        can use either of these to select a constant color from the
        current palette.

        "palette z" maps the z value of each plot segment or plot ele-
        ment into the cbrange mapping of the palette. This allows
        smoothly-varying color along a 3d line or surface. It also
        allows coloring 2D plots by palette values read from an extra
        column of data (not all 2D plot styles allow an extra column).




             1177..11..11..  RRggbbccoolloorr vvaarriiaabbllee


             Most plot commands assign a single color (linetype) to
             each element of the plot.  If there are multiple plots on
             a single graph, the default color (linetype) is incre-
             mented sequentially.  You can instead assign a separate
             color for each data point, line segment, or label based on
             additional information in the input data file.  This is
             indicated by the colorspec keyword vvaarriiaabbllee.

             llcc rrggbbccoolloorr vvaarriiaabbllee tells the program to use a 24-bit RGB
             color from a separate column in the data file. This
             requires a corresponding additional column in the uussiinngg
             specifier.  The extra column is interpreted as a 24-bit
             packed RGB triple. These are most easily specified as hex-
             idecimal values (see rrggbbccoolloorr). Text colors are similarly
             set using ttcc rrggbbccoolloorr vvaarriiaabbllee.

             Example:

                   # Place colored points in 3D at the x,y,z coordi-
             nates corresponding to
                   # their red, green, and blue components
                   rgb(r,g,b) = 65536 * int(r) + 256 * int(g) + int(b)
                   splot "data" using 1:2:3:(rgb($1,$2,$3)) with points
             lc rgb variable




             1177..11..22..  LLiinneeccoolloorr vvaarriiaabbllee













   GNUPLOT 4.1                                                       30


             Most plot commands assign a single color (linetype) to
             each element of the plot.  If there are multiple plots on
             a single graph, the default color (linetype) is incre-
             mented sequentially.  You can instead assign a separate
             color for each data point, line segment, or label based on
             additional information in the input data file.  This is
             indicated by the colorspec keyword vvaarriiaabbllee.

             llcc vvaarriiaabbllee tells the program to use the value read from
             one column of the input data as a linestyle index, and use
             the color belonging to that linestyle.  This requires a
             corresponding additional column in the uussiinngg specifier.
             Text colors can be set similarly using ttcc vvaarriiaabbllee.

             A single data file may contain multiple sets of data, sep-
             arated by two blank lines. Each of these separate sets is
             assigned an index value (see iinnddeexx) that can be retrieved
             via the using specifier column(-2). See ppsseeuuddooccoolluummnnss.
             All data in the file is drawn with the same
             color/linestyle/pointtype properties by default.  The com-
             mand llcc vvaarriiaabbllee can be used to assign different colors to
             each data set in the file by using the index value from
             pseudocolumn -2.

             Examples:
                   # Use the third column of data to assign colors to
             individual points
                   plot 'data' using 1:2:3 with points lc variable

                   # Use the data set index to choose a linestyle color
                   plot 'data' using 1:2:(column(-2)) with lines lc
             variable




   1188..  MMoouussee iinnppuutt


   The xx1111, ppmm, wwiinnddoowwss, ggggii, and wwxxtt terminals allow interaction with
   the current plot using the mouse. They also support the definition
   of hotkeys to activate pre-defined functions by hitting a single key
   while the mouse focus is in the active plot window.  It is even pos-
   sible to combine mouse input with bbaattcchh command scripts, by invoking
   the command ppaauussee mmoouussee and then using the mouse variables returned
   by mouse clicking as parameters for subsequent scripted actions. See
   bbiinndd and mmoouussee vvaarriiaabblleess.  See also the command sseett mmoouussee.
















   GNUPLOT 4.1                                                       31


        1188..11..  BBiinndd


        Syntax:
              bind {allwindows} [<key-sequence>] ["<gnuplot commands>"]
              bind <key-sequence> ""
              reset bind

        The bbiinndd allows defining or redefining a hotkey, i.e. a
        sequence of gnuplot commands which will be executed when a cer-
        tain key or key sequence is pressed while the driver's window
        has the input focus. Note that bbiinndd is only available if gnu-
        plot was compiled with mmoouussee support and it is used by all
        mouse-capable terminals. A user-specified binding supersedes
        any builtin bindings, except that <space> and 'q' cannot nor-
        mally be rebound. For an exception, see bbiinndd ssppaaccee.

        Mouse buttons cannot be rebound.

        You get the list of all hotkeys by typing sshhooww bbiinndd or bbiinndd or
        by typing the hotkey 'h' in the graph window.

        Key bindings are restored to their default state by rreesseett bbiinndd.

        Note that multikey-bindings with modifiers must be given in
        quotes.

        Normally hotkeys are only recognized when the currently active
        plot window has focus. bbiinndd aallllwwiinnddoowwss <<kkeeyy>> ...... (short form:
        bbiinndd aallll <<kkeeyy>> ......)  causes the binding for <key> to apply to
        all gnuplot plot windows, active or not.  In this case gnuplot
        variable MOUSE_KEY_WINDOW is set to the ID of the originating
        window, and may be used by the bound command.

        Examples:

        - set bindings:

            bind a "replot"
            bind "ctrl-a" "plot x*x"
            bind "ctrl-alt-a" 'print "great"'
            bind Home "set view 60,30; replot"
            bind all Home 'print "This is window ",MOUSE_KEY_WINDOW'

        - show bindings:
            bind "ctrl-a"          # shows the binding for ctrl-a
            bind                   # shows all bindings
            show bind              # show all bindings

        - remove bindings:
            bind "ctrl-alt-a" ""   # removes binding for ctrl-alt-a
                                     (note that builtins cannot be
        removed)










   GNUPLOT 4.1                                                       32


            reset bind             # installs default (builtin) bind-
        ings
            bind!                  # deprecated form of "reset bind"

        - bind a key to toggle something:
          v=0
          bind "ctrl-r" "v=v+1;if(v%2)set term x11 noraise; else set
        term x11 raise"

        Modifiers (ctrl / alt) are case insensitive, keys not:
            ctrl-alt-a == CtRl-alT-a
            ctrl-alt-a != ctrl-alt-A

        List of modifiers (alt == meta):
            ctrl, alt

        List of supported special keys:

           "BackSpace", "Tab", "Linefeed", "Clear", "Return", "Pause",
        "Scroll_Lock",
           "Sys_Req", "Escape", "Delete", "Home", "Left", "Up",
        "Right", "Down",
           "PageUp", "PageDown", "End", "Begin",

           "KP_Space", "KP_Tab", "KP_Enter", "KP_F1", "KP_F2", "KP_F3",
        "KP_F4",
           "KP_Home", "KP_Left", "KP_Up", "KP_Right", "KP_Down",
        "KP_PageUp",
           "KP_PageDown", "KP_End", "KP_Begin", "KP_Insert",
        "KP_Delete", "KP_Equal",
           "KP_Multiply", "KP_Add", "KP_Separator", "KP_Subtract",
        "KP_Decimal",
           "KP_Divide",

           "KP_1" - "KP_9", "F1" - "F12"

        The following are window events rather than actual keys

           "Close"

        See also help for mmoouussee and iiff.




             1188..11..11..  BBiinndd ssppaaccee


             If gnuplot was built with configuration option --enable-
             raise-console, then typing <space> in the plot window
             raises gnuplot's command window. This hotkey can be
             changed to ctrl-space by starting gnuplot as 'gnuplot
             -ctrlq', or by setting the XResource 'gnuplot*ctrlq'.  See










   GNUPLOT 4.1                                                       33


             xx1111 ccoommmmaanndd--lliinnee--ooppttiioonnss.



        1188..22..  MMoouussee vvaarriiaabblleess


        When mmoouussiinngg is active, clicking in the active window will set
        several user variables that can be accessed from the gnuplot
        command line. The coordinates of the mouse at the time of the
        click are stored in MOUSE_X MOUSE_Y MOUSE_X2 and MOUSE_Y2. The
        mouse button clicked, and any meta-keys active at that time,
        are stored in MOUSE_BUTTON MOUSE_SHIFT MOUSE_ALT and
        MOUSE_CTRL.  These variables are set to undefined at the start
        of every plot, and only become defined in the event of a mouse
        click in the active plot window. To determine from a script if
        the mouse has been clicked in the active plot window, it is
        sufficient to test for any one of these variables being
        defined.

              plot 'something'
              pause mouse
              if (defined(MOUSE_BUTTON)) call 'something_else'; \
              else print "No mouse click."

        It is also possible to track keystrokes in the plot window
        using the mousing code.

              plot 'something'
              pause mouse keypress
              print "Keystroke ", MOUSE_KEY, " at ", MOUSE_X, " ",
        MOUSE_Y

        When ppaauussee mmoouussee kkeeyypprreessss is terminated by a keypress, then
        MOUSE_KEY will contain the ascii character value of the key
        that was pressed. MOUSE_CHAR will contain the character itself
        as a string variable.  If the pause command is terminated
        abnormally (e.g. by ctrl-C or by externally closing the plot
        window) then MOUSE_KEY will equal -1.

        Note that after a zoom by mouse, you can read the new ranges as
        GPVAL_X_MIN, GPVAL_X_MAX, GPVAL_Y_MIN, and GPVAL_Y_MAX, see
        ggnnuupplloott--ddeeffiinneedd vvaarriiaabblleess.





   1199..  PPlloottttiinngg


   There are three ggnnuupplloott commands which actually create a plot: pplloott,
   sspplloott and rreepplloott.  pplloott generates 2D plots, sspplloott generates 3-d










   GNUPLOT 4.1                                                       34


   plots (actually 2D projections, of course), and rreepplloott appends its
   arguments to the previous pplloott or sspplloott and executes the modified
   command.

   Much of the general information about plotting can be found in the
   discussion of pplloott; information specific to 3D can be found in the
   sspplloott section.

   pplloott operates in either rectangular or polar coordinates -- see sseett
   ppoollaarr for details of the latter.  sspplloott operates only in rectangular
   coordinates, but the sseett mmaappppiinngg command allows for a few other
   coordinate systems to be treated.  In addition, the uussiinngg option
   allows both pplloott and sspplloott to treat almost any coordinate system
   you'd care to define.

   pplloott also lets you use each of the four borders -- x (bottom), x2
   (top), y (left) and y2 (right) -- as an independent axis.  The aaxxeess
   option lets you choose which pair of axes a given function or data
   set is plotted against.  A full complement of sseett commands exists to
   give you complete control over the scales and labelling of each
   axis.  Some commands have the name of an axis built into their
   names, such as sseett xxllaabbeell.  Other commands have one or more axis
   names as options, such as sseett llooggssccaallee xxyy.  Commands and options
   controlling the z axis have no effect on 2D graphs.

   sspplloott can plot surfaces and contours in addition to points and/or
   lines.  In addition to sspplloott, see sseett iissoossaammpplleess for information
   about defining the grid for a 3D function;  sspplloott ddaattaaffiillee for
   information about the requisite file structure for 3D data values;
   and sseett ccoonnttoouurr and sseett ccnnttrrppaarraamm for information about contours.

   In sspplloott, control over the scales and labels of the axes are the
   same as with pplloott, except that commands and options controlling the
   x2 and y2 axes have no effect whereas of course those controlling
   the z axis do take effect.



   2200..  SSttaarrtt--uupp


   When ggnnuupplloott is run, it looks for an initialization file to load.
   This file is called ..ggnnuupplloott on Unix and AmigaOS systems, and GGNNUU--
   PPLLOOTT..IINNII on other systems.  If this file is not found in the current
   directory, the program will look for it in the HOME directory (under
   AmigaOS, MS-DOS, Windows and OS/2, the environment variable GGNNUUPPLLOOTT
   should contain the name of this directory; on Windows NT, it will
   use UUSSEERRPPRROOFFIILLEE if GNUPLOT isn't defined).  Note: if NOCWDRC is
   defined during the installation, ggnnuupplloott will not read from the cur-
   rent directory.

   If the initialization file is found, ggnnuupplloott executes the commands
   in it.  These may be any legal ggnnuupplloott commands, but typically they










   GNUPLOT 4.1                                                       35


   are limited to setting the terminal and defining frequently-used
   functions or variables.



   2211..  SSttrriinngg ccoonnssttaannttss aanndd ssttrriinngg vvaarriiaabblleess


   In addition to string constants, most gnuplot commands also accept a
   string variable, a string expression, or a function that returns a
   string.  For example, the following four methods of creating a plot
   all result in the same plot title:

         four = "4"
         graph4 = "Title for plot #4"
         graph(n) = sprintf("Title for plot #%d",n)

         plot 'data.4' title "Title for plot #4"
         plot 'data.4' title graph4
         plot 'data.4' title "Title for plot #".four
         plot 'data.4' title graph(4)

   Since integers are promoted to strings when operated on by the
   string concatenation operator, the following method also works:

         N = 4
         plot 'data.'.N title "Title for plot #".N

   In general, elements on the command line will only be evaluated as
   possible string variables if they are not otherwise recognizable as
   part of the normal gnuplot syntax. So the following sequence of com-
   mands is legal, although probably should be avoided so as not to
   cause confusion:

         plot = "my_datafile.dat"
         title = "My Title"
         plot plot title title

   There are three binary operators that require string operands: the
   string concatenation operator ".", the string equality operator "eq"
   and the string inequality operator "ne".  The following example will
   print TRUE.

        if ("A"."B" eq "AB") print "TRUE"

   See also the two string formatting functions ggpprriinnttff and sspprriinnttff.

   Substrings can be specified by appending a range specifier to any
   string, string variable, or string-valued function.  The range spec-
   ifier has the form [begin:end], where begin is the index of the
   first character of the substring and end is the index of the last
   character of the substring.  The first character has index 1.  The
   begin or end fields may be empty, or contain '*', to indicate the










   GNUPLOT 4.1                                                       36


   true start or end of the original string.  E.g.  str[:] and str[*:*]
   both describe the full string str.



   2222..  SSuubbssttiittuuttiioonn aanndd CCoommmmaanndd lliinnee mmaaccrrooss


   When a command line to gnuplot is first read, i.e. before it is
   interpreted or executed, two forms of lexical substitution are per-
   formed. These are triggered by the presence of text in backquotes
   (ascii character 96) or preceded by @ (ascii character 64).




        2222..11..  SSuubbssttiittuuttiioonn ooff ssyysstteemm ccoommmmaannddss iinn bbaacckkqquuootteess


        Command-line substitution is specified by a system command
        enclosed in backquotes.  This command is spawned and the output
        it produces replaces the backquoted text on the command line.
        Some implementations also support pipes;  see pplloott ddaattaaffiillee
        ssppeecciiaall--ffiilleennaammeess.

        Command-line substitution can be used anywhere on the ggnnuupplloott
        command line, except inside strings delimited by single quotes.

        Example:

        This will run the program lleeaassttssqq and replace lleeaassttssqq (includ-
        ing backquotes) on the command line with its output:
              f(x) = `leastsq`

        or, in VMS
              f(x) = `run leastsq`

        These will generate labels with the current time and userid:
              set label "generated on `date +%Y-%m-%d` by `whoami`" at
        1,1
              set timestamp "generated on %Y-%m-%d by `whoami`"



        2222..22..  SSuubbssttiittuuttiioonn ooff ssttrriinngg vvaarriiaabblleess aass mmaaccrrooss


        Substitution of command line macros is disabled by default, but
        may be enabled using the sseett mmaaccrrooss command.  If macro substi-
        tution is enabled, the character @ is used to trigger substitu-
        tion of the current value of a string variable into the command
        line. The text in the string variable may contain any number of
        lexical elements.  This allows string variables to be used as










   GNUPLOT 4.1                                                       37


        command line macros.  Only string constants may be expanded
        using this mechanism, not string-valued expressions.  For exam-
        ple:

              set macros
              style1 = "lines lt 4 lw 2"
              style2 = "points lt 3 pt 5 ps 2"
              range1 = "using 1:3"
              range2 = "using 1:5"
              plot "foo" @range1 with @style1, "bar" @range2 with
        @style2

        The line containing @ symbols is expanded on input, so that by
        the time it is executed the effect is identical to having typed
        in full

              plot "foo" using 1:3 with lines lt 4 lw 2, \
                   "bar" using 1:5 with points lt 3 pt 5 ps 2

        The function exists() may be useful in connection with macro
        evaluation.  The following example checks that C can safely be
        expanded as the name of a user-defined variable:

              C = "pi"
              if (exists(C)) print C," = ", @C

        Macro expansion does not occur inside either single or double
        quotes.  However macro expansion does occur inside backquotes.

        For execution of complete commands the eevvaalluuaattee command may
        also be handy.



        2222..33..  SSttrriinngg vvaarriiaabblleess,, mmaaccrrooss,, aanndd ccoommmmaanndd lliinnee ssuubbssttiittuuttiioonn


        The interaction of string variables, backquotes and macro sub-
        stitution is somewhat complicated.  Backquotes do not block
        macro substitution, so

              filename = "mydata.inp"
              lines = ` wc --lines @filename | sed "s/ .*//" `

        results in the number of lines in mydata.inp being stored in
        the integer variable lines. And double quotes do not block
        backquote substitution, so

              mycomputer = "`uname -n`"

        results in the string returned by the system command uunnaammee --nn
        being stored in the string variable mycomputer.











   GNUPLOT 4.1                                                       38


        However, macro substitution is not performed inside double
        quotes, so you cannot define a system command as a macro and
        then use both macro and backquote substitution at the same
        time.

               machine_id = "uname -n"
               mycomputer = "`@machine_id`"  # doesn't work!!

        This fails because the double quotes prevent @machine_id from
        being interpreted as a macro. To store a system command as a
        macro and execute it later you must instead include the back-
        quotes as part of the macro itself.  This is accomplished by
        defining the macro as shown below.  Notice that the sprintf
        format nests all three types of quotes.

              machine_id = sprintf('"`uname -n`"')
              mycomputer = @machine_id



   2233..  SSyynnttaaxx


   Version 4 of gnuplot is much less sensitive than earlier versions to
   the order of keywords and suboptions. However, if you get error mes-
   sages from specifying options that you think should work, please try
   rearranging them into the exact order listed by the documentation.

   Options and any accompanying parameters are separated by spaces
   whereas lists and coordinates are separated by commas.  Ranges are
   separated by colons and enclosed in brackets [], text and file names
   are enclosed in quotes, and a few miscellaneous things are enclosed
   in parentheses.  Braces {} are used for a few special purposes.

   Commas are used to separate coordinates on the sseett commands aarrrrooww,
   kkeeyy, and llaabbeell; the list of variables being fitted (the list after
   the vviiaa keyword on the ffiitt command); lists of discrete contours or
   the loop parameters which specify them on the sseett ccnnttrrppaarraamm command;
   the arguments of the sseett commands ddggrriidd33dd, dduummmmyy, iissoossaammpplleess, ooffff--
   sseettss, oorriiggiinn, ssaammpplleess, ssiizzee, ttiimmee, and vviieeww; lists of tics or the
   loop parameters which specify them; the offsets for titles and axis
   labels; parametric functions to be used to calculate the x, y, and z
   coordinates on the pplloott, rreepplloott and sspplloott commands; and the complete
   sets of keywords specifying individual plots (data sets or func-
   tions) on the pplloott, rreepplloott and sspplloott commands.

   Parentheses are used to delimit sets of explicit tics (as opposed to
   loop parameters) and to indicate computations in the uussiinngg filter of
   the ffiitt, pplloott, rreepplloott and sspplloott commands.

   (Parentheses and commas are also used as usual in function nota-
   tion.)











   GNUPLOT 4.1                                                       39


   Square brackets are used to delimit ranges given in sseett, pplloott or
   sspplloott commands.

   Colons are used to separate extrema in rraannggee specifications (whether
   they are given on sseett, pplloott or sspplloott commands) and to separate
   entries in the uussiinngg filter of the pplloott, rreepplloott, sspplloott and ffiitt com-
   mands.

   Semicolons are used to separate commands given on a single command
   line.

   Braces are used in text to be specially processed by some terminals,
   like ppoossttssccrriipptt.  They are also used to denote complex numbers:
   {3,2} = 3 + 2i.

   At present you should not embed \n inside {} when using the Post-
   Script terminal in eennhhaanncceedd tteexxtt mode.

   The EEPIC, Imagen, Uniplex, LaTeX, and TPIC drivers allow a newline
   to be specified by \\ in a single-quoted string or \\\\ in a double-
   quoted string.




        2233..11..  QQuuoottee MMaarrkkss


        Gnuplot uses three forms of quote marks for delimiting text
        strings, double-quote (ascii 34), single-quote (ascii 39), and
        backquote (ascii 96).

        Filenames may be entered with either single- or double-quotes.
        In this manual the command examples generally single-quote
        filenames and double-quote other string tokens for clarity.

        String constants and text strings used for labels, titles, or
        other plot elements may be enclosed in either single quotes or
        double quotes. Further processing of the quoted text depends on
        the choice of quote marks.

        Backslash processing of special characters like \n (newline)
        and \345 (octal character code) is performed for double-quoted
        strings.  In single-quoted strings, backslashes are just ordi-
        nary characters.  To get a single-quote (ascii 39) in a single-
        quoted string, it has to be doubled.  Thus the strings "d\" s'
        b\\" and 'd" s'' b\' are completely equivalent.

        Text justification is the same for each line of a multi-line
        string.  Thus the center-justified string
              "This is the first line of text.\nThis is the second
        line."
        will produce










   GNUPLOT 4.1                                                       40


                               This is the first line of text.
                                  This is the second line.
        but
              'This is the first line of text.\nThis is the second
        line.'
        will produce
                  This is the first line of text.\nThis is the second
        line.

        Enhanced text processing is performed for both double-quoted
        text and single-quoted text, but only by terminals supporting
        this mode.  See eennhhaanncceedd tteexxtt.

        Back-quotes are used to enclose system commands for substitu-
        tion into the command line.  See ssuubbssttiittuuttiioonn.



   2244..  TTiimmee//DDaattee ddaattaa


   ggnnuupplloott supports the use of time and/or date information as input
   data.  This feature is activated by the commands sseett xxddaattaa ttiimmee, sseett
   yyddaattaa ttiimmee, etc.

   Internally all times and dates are converted to the number of sec-
   onds from the year 2000.  The command sseett ttiimmeeffmmtt defines the format
   for all inputs: data files, ranges, tics, label positions---in
   short, anything that accepts a data value must receive it in this
   format.  Since only one input format can be in force at a given
   time, all time/date quantities being input at the same time must be
   presented in the same format.  Thus if both x and y data in a file
   are time/date, they must be in the same format.

   The conversion to and from seconds assumes Universal Time (which is
   the same as Greenwich Standard Time).  There is no provision for
   changing the time zone or for daylight savings.  If all your data
   refer to the same time zone (and are all either daylight or stan-
   dard) you don't need to worry about these things.  But if the abso-
   lute time is crucial for your application, you'll need to convert to
   UT yourself.

   Commands like sshhooww xxrraannggee will re-interpret the integer according to
   ttiimmeeffmmtt.  If you change ttiimmeeffmmtt, and then sshhooww the quantity again,
   it will be displayed in the new ttiimmeeffmmtt.  For that matter, if you
   give the deactivation command (like sseett xxddaattaa), the quantity will be
   shown in its numerical form.

   The commands sseett ffoorrmmaatt or sseett ttiiccss ffoorrmmaatt define the format that
   will be used for tic labels, whether or not the specified axis is
   time/date.

   If time/date information is to be plotted from a file, the uussiinngg










   GNUPLOT 4.1                                                       41


   option _must_ be used on the pplloott or sspplloott command.  These commands
   simply use white space to separate columns, but white space may be
   embedded within the time/date string.  If you use tabs as a separa-
   tor, some trial-and-error may be necessary to discover how your sys-
   tem treats them.

   The following example demonstrates time/date plotting.

   Suppose the file "data" contains records like

         03/21/95 10:00  6.02e23

   This file can be plotted by

         set xdata time
         set timefmt "%m/%d/%y"
         set xrange ["03/21/95":"03/22/95"]
         set format x "%m/%d"
         set timefmt "%m/%d/%y %H:%M"
         plot "data" using 1:3

   which will produce xtic labels that look like "03/21".

   See ttiimmee__ssppeecciiffiieerrss.




   2255..  PPlloottttiinngg ssttyylleess



   There are many plotting styles available in gnuplot.  They are
   listed alphabetically below.  The commands sseett ssttyyllee ddaattaa and sseett
   ssttyyllee ffuunnccttiioonn change the default plotting style for subsequent pplloott
   and sspplloott commands.

   You also have the option to specify the plot style explicitly as
   part of the pplloott or sspplloott command.  If you want to mix plot styles
   within a single plot, you must specify the plot style for each com-
   ponent.

   Example:

        plot 'data' with boxes, sin(x) with lines

   Each plot style has its own expected set of data entries in a data
   file.  For example by default the lliinneess style expects either a sin-
   gle column of y values (with implicit x ordering) or a pair of col-
   umns with x in the first and y in the second.  For more information
   on how to fine-tune how columns in a file are interpreted as plot
   data, see uussiinngg.











   GNUPLOT 4.1                                                       42


   2266..  BBooxxeerrrroorrbbaarrss


   The bbooxxeerrrroorrbbaarrss style is only relevant to 2D data plotting.  It is
   a combination of the bbooxxeess and yyeerrrroorrbbaarrss styles.  It uses 3, 4, or
   5 columns of data:

        3 columns:  x  y  ydelta
        4 columns:  x  y  ydelta xdelta        # boxwidth != -2
        4 columns:  x  y  ylow  yhigh          # boxwidth == -2
        5 columns:  x  y  ylow  yhigh  xdelta

   The boxwidth will come from the fourth column if the y errors are
   given as "ydelta" and the boxwidth was not previously set to -2.0
   (sseett bbooxxwwiiddtthh --22..00) or from the fifth column if the y errors are in
   the form of "ylow yhigh".  The special case  bbooxxwwiiddtthh == --22..00 is for
   four-column data with y errors in the form "ylow yhigh".  In this
   case the boxwidth will be calculated so that each box touches the
   adjacent boxes.  The width will also be calculated in cases where
   three-column data are used.

   The box height is determined from the y error in the same way as it
   is for the yyeerrrroorrbbaarrss style---either from y-ydelta to y+ydelta or
   from ylow to yhigh, depending on how many data columns are provided.
   See also errorbar demo.



   2277..  BBooxxeess


   The bbooxxeess style is only relevant to 2D plotting.  It draws a box
   centered about the given x coordinate that extends from the x axis
   (not from the graph border) to the given y coordinate.  It uses 2 or
   3 columns of basic data.  Additional input columns may be used to
   provide information such as variable line or fill color (see rrggbb--
   ccoolloorr vvaarriiaabbllee).

        2 columns:  x  y
        3 columns:  x  y  x_width

   The width of the box is obtained in one of three ways.  If the input
   data has a third column, this will be used to set the width of the
   box.  If not, if a width has been set using the sseett bbooxxwwiiddtthh com-
   mand, this will be used.  If neither of these is available, the
   width of each box will be calculated automatically so that it
   touches the adjacent boxes.

   The interior of the boxes is drawn according to the current fill-
   style.  See sseett ssttyyllee ffiillll for details.  Alternatively a new fill-
   style may be specified in the plot command.

   For fillstyle eemmppttyy the box is not filled.










   GNUPLOT 4.1                                                       43


   For fillstyle ssoolliidd the box is filled with a solid rectangle of the
   current drawing color. There is an optional parameter <density> that
   controls the fill density; it runs from 0 (background color) to 1
   (current drawing color).

   For fillstyle ppaatttteerrnn the box is filled in the current drawing color
   with a pattern, if supported by the terminal driver.

   Examples:

   To plot a data file with solid filled boxes with a small vertical
   space separating them (bargraph):

         set boxwidth 0.9 relative
         set style fill solid 1.0
         plot 'file.dat' with boxes

   To plot a sine and a cosine curve in pattern-filled boxes style:

         set style fill pattern
         plot sin(x) with boxes, cos(x) with boxes

   The sin plot will use pattern 0; the cos plot will use pattern 1.
   Any additional plots would cycle through the patterns supported by
   the terminal driver.

   To specify explicit fillstyles for each dataset:

        plot 'file1' with boxes fs solid 0.25, \
             'file2' with boxes fs solid 0.50, \
             'file3' with boxes fs solid 0.75, \
             'file4' with boxes fill pattern 1, \
             'file5' with boxes fill empty




   2288..  BBooxxxxyyeerrrroorrbbaarrss


   The bbooxxxxyyeerrrroorrbbaarrss style is only relevant to 2D data plotting.  It
   is similar to the xxyyeerrrroorrbbaarrss style except that it draws rectangular
   areas rather than simple crosses.  It uses either 4 or 6 basic col-
   umns of input data.  Additional input columns may be used to provide
   information such as variable line or fill color (see rrggbbccoolloorr vvaarrii--
   aabbllee).

        4 columns:  x  y  xdelta  ydelta
        6 columns:  x  y  xlow  xhigh  ylow  yhigh

   The box width and height are determined from the x and y errors in
   the same way as they are for the xxyyeerrrroorrbbaarrss style---either from
   xlow to xhigh and from ylow to yhigh, or from x-xdelta to x+xdelta










   GNUPLOT 4.1                                                       44


   and from y-ydelta to y+ydelta, depending on how many data columns
   are provided.

   The interior of the boxes is drawn according to the current fill-
   style.  See sseett ssttyyllee ffiillll and bbooxxeess for details.  Alternatively a
   new fillstyle may be specified in the plot command.



   2299..  CCaannddlleessttiicckkss


   The ccaannddlleessttiicckkss style can be used for 2D data plotting of financial
   data or for generating box-and-whisker plots of statistical data.
   The symbol is a rectangular box, centered horizontally at the x
   coordinate and limited vertically by the opening and closing prices.
   A vertical line segment at the x coordinate extends up from the top
   of the rectangle to the high price and another down to the low.  The
   vertical line will be unchanged if the low and high prices are
   interchanged.

   Five columns of basic data are required:

         financial data:   date  open  low  high  close
         whisker plot:     x  box_min  whisker_min  whisker_high
   box_high

   The width of the rectangle can be controlled by the sseett bbooxxwwiiddtthh
   command.  For backwards compatibility with earlier gnuplot versions,
   when the boxwidth parameter has not been set then the width of the
   candlestick rectangle is controlled by sseett bbaarrss <<wwiiddtthh>>.

   Alternatively, an explicit width for each box-and-whiskers grouping
   may be specified in an optional 6th column of data.  The width must
   be given in the same units as the x coordinate.

   By default the vertical line segments have no crossbars at the top
   and bottom. If you want crossbars, which are typically used for box-
   and-whisker plots, then add the keyword wwhhiisskkeerrbbaarrss to the plot com-
   mand.  By default these whiskerbars extend the full horizontal width
   of the candlestick, but you can modify this by specifying a fraction
   of the full width.

   The usual convention for financial data is that the rectangle is
   empty if (open < close) and solid fill if (close < open). This is
   the behavior you will get if the current fillstyle is set to
   "empty". See ffiillllssttyyllee.  If you set the fillstyle to solid or pat-
   tern, then this will be used for all boxes independent of open and
   close values.  See also sseett bbaarrss and ffiinnaanncceebbaarrss.  See also the can-
   dlestick and finance demos.

   Note: To place additional symbols, such as the median value, on a
   box-and-whisker plot requires additional plot commands as in this










   GNUPLOT 4.1                                                       45


   example:

     # Data columns:X Min 1stQuartile Median 3rdQuartile Max
     set bars 4.0
     set style fill empty
     plot 'stat.dat' using 1:3:2:6:5 with candlesticks title 'Quar-
   tiles', \
          ''         using 1:4:4:4:4 with candlesticks lt -1 notitle

     # Plot with crossbars on the whiskers, crossbars are 50% of full
   width
     plot 'stat.dat' using 1:3:2:6:5 with candlesticks whiskerbars 0.5

   See sseett bbooxxwwiiddtthh, sseett bbaarrss and sseett ssttyyllee ffiillll.



   3300..  CCiirrcclleess


   The cciirrcclleess style plots a circle with an explicit radius at each
   data point.  Three columns of data are required: x, y, radius.  An
   optional 4th column may be used to specify color information.  The
   radius is always interpreted in the units of the plot's horizontal
   axis (x or x2).  The scale on y and the aspect ratio of the plot are
   both ignored.  If only two columns are present, the radius is taken
   from sseett ssttyyllee cciirrccllee.  In this case the radius may be given in
   graph or screen coordinates.

   Example (draws circles whose area is proportional to the value in
   column 3):

       set style fill transparent solid 0.2 noborder
       plot 'data' using 1:2:(sqrt($3)) with circles, \
            'data' using 1:2 with linespoints

   The result is similar to using a ppooiinnttss plot with variable size
   points and pointstyle 6, except that the circles will scale with the
   x axis range.  See also sseett oobbjjeecctt cciirrccllee and ffiillllssttyyllee.



   3311..  DDoottss


   The ddoottss style plots a tiny dot at each point; this is useful for
   scatter plots with many points.  Either 1 or 2 columns of input data
   are required in 2D.  Three columns are required in 3D.

   For some terminals (post, pdf) the size of the dot can be controlled
   by changing the linewidth.

        1 column    y         # x is row number










   GNUPLOT 4.1                                                       46


        2 columns:  x  y
        3 columns:  x  y  z   # 3D only (splot)




   3322..  FFiilllleeddccuurrvveess


   The ffiilllleeddccuurrvveess style is only relevant to 2D plotting. Three vari-
   ants are possible. The first two variants require either a function
   or two columns of input data, and may be further modified by the
   options listed below.

   Syntax:

       plot ... with filledcurves [option]

   where the option can be one of the following

       [closed | {above | below}
       {x1 | x2 | y1 | y2}[=<a>] | xy=<x>,<y>]

   The first variant, cclloosseedd, treats the curve itself as a closed poly-
   gon.  This is the default if there are two columns of input data.

   The second variant is to fill the area between the curve and a given
   axis, a horizontal or vertical line, or a point.

       filledcurves closed   ... just filled closed curve,
       filledcurves x1       ... x1 axis,
       filledcurves x2       ... x2 axis, etc for y1 and y2 axes,
       filledcurves y1=0     ... line y=0 (at y1 axis) ie parallel to
   x1 axis,
       filledcurves y2=42    ... line y=42 (at y2 axis) ie parallel to
   x2, etc,
       filledcurves xy=10,20 ... point 10,20 of x1,y1 axes (arc-like
   shape).

   The third variant requires three columns of input data: the x coor-
   dinate and two y coordinates corresponding to two curves sampled at
   the same set of x coordinates; the area between the two curves is
   filled.  This is the default if there are three or more columns of
   input data.

        3 columns:  x  y1  y2

   Example of filling the area between two input curves.  fill between
   curves demo.

       plot 'data' using 1:2:3 with filledcurves

   The aabboovvee and bbeellooww options apply both to commands of the form










   GNUPLOT 4.1                                                       47


       ... filledcurves above {x1|x2|y1|y2}=<val>
   and to commands of the form
       ... using 1:2:3 with filledcurves below
   In either case the option limits the filled area to one side of the
   bounding line or curve.

   Note: Not all terminal types support this plotting mode.

   Zooming a filled curve drawn from a datafile may produce empty or
   incorrect areas because gnuplot is clipping points and lines, and
   not areas.

   If the values of <a>, <x>, <y> are out of the drawing boundary, then
   they are moved to the graph boundary. Then the actually filled area
   in the case of option xy=<x>,<y> will depend on xrange and yrange.



   3333..  FFiinnaanncceebbaarrss


   The ffiinnaanncceebbaarrss style is only relevant for 2D data plotting of
   financial data.  It requires 1 x coordinate (usually a date) and 4 y
   values (prices).

        5 columns:   date  open  low  high  close

   The symbol is a vertical line segment, located horizontally at the x
   coordinate and limited vertically by the high and low prices.  A
   horizontal tic on the left marks the opening price and one on the
   right marks the closing price.  The length of these tics may be
   changed by sseett bbaarrss.  The symbol will be unchanged if the high and
   low prices are interchanged.  See sseett bbaarrss and ccaannddlleessttiicckkss, and
   also the finance demo.



   3344..  FFsstteeppss


   The ffsstteeppss style is only relevant to 2D plotting.  It connects con-
   secutive points with two line segments: the first from (x1,y1) to
   (x1,y2) and the second from (x1,y2) to (x2,y2).  The input column
   requires are the same as for plot styles lliinneess and ppooiinnttss.  The dif-
   ference between ffsstteeppss and sstteeppss is that ffsstteeppss traces first the
   change in y and then the change in x.  sstteeppss traces first the change
   in x and then the change in y.

   See also steps demo.














   GNUPLOT 4.1                                                       48


   3355..  HHiisstteeppss


   The hhiisstteeppss style is only relevant to 2D plotting.  It is intended
   for plotting histograms.  Y-values are assumed to be centered at the
   x-values; the point at x1 is represented as a horizontal line from
   ((x0+x1)/2,y1) to ((x1+x2)/2,y1).  The lines representing the end
   points are extended so that the step is centered on at x.  Adjacent
   points are connected by a vertical line at their average x, that is,
   from ((x1+x2)/2,y1) to ((x1+x2)/2,y2).  The input column requires
   are the same as for plot styles lliinneess and ppooiinnttss.

   If aauuttoossccaallee is in effect, it selects the xrange from the data
   rather than the steps, so the end points will appear only half as
   wide as the others.  See also steps demo.

   hhiisstteeppss is only a plotting style; ggnnuupplloott does not have the ability
   to create bins and determine their population from some data set.



   3366..  HHiissttooggrraammss


   The hhiissttooggrraammss style is only relevant to 2D plotting.  It produces a
   bar chart from a sequence of parallel data columns. Each element of
   the pplloott command must specify a single input data source (e.g. one
   column of the input file), possibly with associated tic values or
   key titles.  Four styles of histogram layout are currently sup-
   ported.

         set style histogram clustered {gap <gapsize>}
         set style histogram errorbars {gap <gapsize>} {<linewidth>}
         set style histogram rowstacked
         set style histogram columnstacked

   The default style corresponds to sseett ssttyyllee hhiissttooggrraamm cclluusstteerreedd ggaapp
   22.  In this style, each set of parallel data values is collected
   into a group of boxes clustered at the x-axis coordinate correspond-
   ing to their sequential position (row #) in the selected datafile
   columns.  Thus if <n> datacolumns are selected, the first cluster is
   centered about x=1, and contains <n> boxes whose heights are taken
   from the first entry in the corresponding <n> data columns.  This is
   followed by a gap and then a second cluster of boxes centered about
   x=2 corresponding to the second entry in the respective data col-
   umns, and so on.  The default gap width of 2 indicates that the
   empty space between clusters is equivalent to the width of 2 boxes.
   All boxes derived from any one column are given the same fill color
   and/or pattern (see sseett ssttyyllee ffiillll).

   Each cluster of boxes is derived from a single row of the input data
   file.  It is common in such input files that the first element of
   each row is a label. Labels from this column may be placed along the










   GNUPLOT 4.1                                                       49


   x-axis underneath the appropriate cluster of boxes with the xxttiiccllaa--
   bbeellss option to uussiinngg.

   The eerrrroorrbbaarrss style is very similar to the cclluusstteerreedd style, except
   that it requires additional columns of input for each entry. The
   first column holds the height (y value) of that box, exactly as for
   the cclluusstteerreedd style.
        2 columns:        y yerr          bar extends from y-yerr to
   y+err
        3 columns:        y ymin yman     bar extends from ymin to ymax
   The appearance of the error bars is controlled by the current value
   of sseett bbaarrss and by the optional <linewidth> specification.

   Two styles of stacked histogram are supported, chosen by the command
   sseett ssttyyllee hhiissttooggrraamm {{rroowwssttaacckkeedd||ccoolluummnnssttaacckkeedd}}.  In these styles the
   data values from the selected columns are collected into stacks of
   boxes.  Positive values stack upwards from y=0; negative values
   stack downwards.  Mixed positive and negative values will produce
   both an upward stack and a downward stack.  The default stacking
   mode is rroowwssttaacckkeedd.

   The rroowwssttaacckkeedd style places a box resting on the x-axis for each
   data value in the first selected column; the first data value
   results in a box a x=1, the second at x=2, and so on.  Boxes corre-
   sponding to the second and subsequent data columns are layered on
   top of these, resulting in a stack of boxes at x=1 representing the
   first data value from each column, a stack of boxes at x=2 repre-
   senting the second data value from each column, and so on.  All
   boxes derived from any one column are given the same fill color
   and/or pattern (see sseett ssttyyllee ffiillll).

   The ccoolluummnnssttaacckkeedd style is similar, except that each stack of boxes
   is built up from a single data column. Each data value from the
   first specified column yields a box in the stack at x=1, each data
   value from the second specified column yields a box in the stack at
   x=2, and so on.  In this style the color of each box is taken from
   the row number, rather than the column number, of the corresponding
   data field.

   Box widths may be modified using the sseett bbooxxwwiiddtthh command.  Box fill
   styles may be set using the sseett ssttyyllee ffiillll command.

   Histograms always use the x1 axis, but may use either y1 or y2.  If
   a plot contains both histograms and other plot styles, the non-his-
   togram plot elements may use either the x1 or the x2 axis.

   Examples: Suppose that the input file contains data values in col-
   umns 2, 4, 6, ...  and error estimates in columns 3, 5, 7, ...  This
   example plots the values in columns 2 and 4 as a histogram of clus-
   tered boxes (the default style).  Because we use iteration in the
   plot command, any number of data columns can be handled in a single
   command. See iitteerraattiioonn.











   GNUPLOT 4.1                                                       50


         set boxwidth 0.9 relative
         set style data histograms
         set style histogram cluster
         set style fill solid 1.0 border lt -1
         plot for [COL=2:4:2] 'file.dat' using COL

   This will produce a plot with clusters of two boxes (vertical bars)
   centered at each integral value on the x axis.  If the first column
   of the input file contains labels, they may be placed along the x-
   axis using the variant command

         plot for [COL=2:4:2] 'file.dat' using COL:xticlabels(1)

   If the file contains both magnitude and range information for each
   value, then error bars can be added to the plot.  The following com-
   mands will add error bars extending from (y-<error>) to (y+<error>),
   capped by horizontal bar ends drawn the same width as the box
   itself. The error bars and bar ends are drawn with linewidth 2,
   using the border linetype from the current fill style.

         set bars fullwidth
         set style fill solid 1 border lt -1
         set style histogram errorbars gap 2 lw 2
         plot for [COL=2:4:2] 'file.dat' using COL:COL+1

   To plot the same data as a rowstacked histogram.  Just to be differ-
   ent, this example lists the separate columns explicitly rather than
   using iteration.

         set style histogram rowstacked
         plot 'file.dat' using 2, '' using 4:xtic(1)

   This will produce a plot in which each vertical bar corresponds to
   one row of data.  Each vertical bar contains a stack of two seg-
   ments, corresponding in height to the values found in columns 2 and
   4 of the datafile.

   Finally, the commands

         set style histogram columnstacked
         plot 'file.dat' using 2, '' using 4

   will produce two vertical stacks, one for each column of data.  The
   stack at x=1 will contain a box for each entry in column 2 of the
   datafile.  The stack at x=2 will contain a box for each parallel
   entry in column 4 of the datafile.  Because this interchanges gnu-
   plot's usual interpretation of input rows and columns, the specifi-
   cation of key titles and x-axis tic labels must also be modified
   accordingly. See the comments given below.

         set style histogram columnstacked
         plot '' u 5:key(1)            # uses first column to generate
   key titles










   GNUPLOT 4.1                                                       51


         plot '' u 5 title columnhead  # uses first row to generate
   xtic labels

   Note that the two examples just given present exactly the same data
   values, but in different formats.




        3366..11..  NNeewwhhiissttooggrraamm


        Syntax:

             newhistogram {"<title>"} {<linetype>} {<fillstyle>} {at
        <x-coord>}

        More than one set of histograms can appear in a single plot. In
        this case you can force a gap between them, and a separate
        label for each set, by using the nneewwhhiissttooggrraamm command.  For
        example

              set style histogram  cluster
              plot newhistogram "Set A", 'a' using 1, '' using 2, ''
        using 3, \
                   newhistogram "Set B", 'b' using 1, '' using 2, ''
        using 3

        The labels "Set A" and "Set B" will appear beneath the respec-
        tive sets of histograms, under the overall x axis label.

        The newhistogram command can also be used to force histogram
        coloring to begin with a specific color (linetype). By default
        colors will continue to increment successively even across his-
        togram boundaries. Here is an example using the same coloring
        for multiple histograms
              plot newhistogram "Set A" lt 4, 'a' using 1, '' using 2,
        '' using 3, \
                   newhistogram "Set B" lt 4, 'b' using 1, '' using 2,
        '' using 3

        Similarly you can force the next histogram to begin with a
        specified fillstyle.  If the fillstyle is set to ppaatttteerrnn, then
        the pattern used for filling will be incremented automatically.

        The aatt <<xx--ccoooorrdd>> option only applies to column-stacked his-
        tograms.
















   GNUPLOT 4.1                                                       52


        3366..22..  AAuuttoommaatteedd iitteerraattiioonn oovveerr mmuullttiippllee ccoolluummnnss


        If you want to create a histogram from many columns of data in
        a single file, it is very convenient to use the plot iteration
        feature.  See iitteerraattiioonn.  For example, to create stacked his-
        tograms of the data in columns 3 through 8

              set style histogram columnstacked
              plot for [i=3:8] "datafile" using i title columnhead



   3377..  IImmaaggee


   The iimmaaggee, rrggbbiimmaaggee, and rrggbbaallpphhaa plotting styles all project a uni-
   formly sampled grid of data values onto a plane  in either a 2D or
   3D.  The input data may be an actual bitmapped image, perhaps con-
   verted from a standard format such as PNG, or a simple array of
   numerical values.

   This figure illustrates generation of a heat map from an array of
   scalar values.  The current palette is used to map each value onto
   the color assigned to the corresponding pixel.
         plot '-' matrix with image
         5 4 3 1 0
         2 2 0 0 1
         0 0 0 1 0
         0 1 2 4 3
         e
         e

   Each pixel (data point) of the input 2D image will become a rectan-
   gle or parallelipiped in the plot. The coordinates of each data
   point will determine the center of the parallelipiped.  That is, an
   M x N set of data will form an image with M x N pixels.  This is
   different from the pm3d plotting style, where an M x N set of data
   will form a surface of (M-1) x (N-1) elements.  The scan directions
   for a binary image data grid can be further controlled by additional
   keywords. See bbiinnaarryy kkeeyywwoorrddss fflliippxx, kkeeyywwoorrddss cceenntteerr, and kkeeyywwoorrddss
   rroottaattee.

   Image data can be scaled to fill a particular rectangle within a 2D
   plot coordinate system by specifying the x and y extent of each
   pixel.  See bbiinnaarryy kkeeyywwoorrddss ddxx and ddyy. To generate the figure at the
   right, the same input image was placed multiple times, each with a
   specified dx, dy, and origin. The input PNG image of a building is
   50x128 pixels.  The tall building was drawn by mapping this using
   ddxx==00..55 ddyy==11..55.  The short building used a mapping ddxx==00..55 ddyy==00..3355.

   The iimmaaggee style handles input pixels containing a grayscale or color
   palette value. Thus 2D plots (pplloott command) require 3 columns of










   GNUPLOT 4.1                                                       53


   data (x,y,value), while 3D plots (sspplloott command) require 4 columns
   of data (x,y,z,value).

   The rrggbbiimmaaggee style handles input pixels that are described by three
   separate values for the red, green, and blue components.  Thus 5D
   data (x,y,r,g,b) is needed for pplloott and 6D data (x,y,z,r,g,b) for
   sspplloott.  The individual red, green, and blue components are assumed
   to lie in the range [0:255].

   The rrggbbaallpphhaa style handles input pixels that contain alpha channel
   (transparency) information in addition to the red, green, and blue
   components.  Thus 6D data (x,y,r,g,b,a) is needed for pplloott and 7D
   data (x,y,z,r,g,b,a) for sspplloott.  The r, g, b, and alpha components
   are assumed to lie in the range [0:255].




        3377..11..  TTrraannssppaarreennccyy


        The rrggbbaallpphhaa plotting style assumes that each pixel of input
        data contains an alpha value in the range [0:255].  A pixel
        with alpha = 0 is purely transparent and does not alter the
        underlying contents of the plot. A pixel with alpha = 255 is
        purely opaque.  All terminal types can handle these two extreme
        cases.  A pixel with 0 < alpha < 255 is partially transparent.
        Only a few terminal types can handle this correctly; other ter-
        minals will approximate this by treating alpha as being either
        0 or 255.



        3377..22..  IImmaaggee ffaaiillssaaffee


        Some terminal drivers provide code to optimize rendering of
        image data within a rectangular 2D area.  However this code is
        known to be imperfect.  This optimized code may be disabled by
        using the keyword ffaaiillssaaffee. E.g.

              plot 'data' with image failsafe



   3388..  IImmppuullsseess


   The iimmppuullsseess style displays a vertical line from y=0 to the y value
   of each point (2D) or from z=0 to the z value of each point (3D).
   Note that the y or z values may be negative.  Data from additional
   columns can be used to control the color of each impulse.  To use
   this style effectively in 3D plots, it is useful to use thick lines










   GNUPLOT 4.1                                                       54


   (linewidth > 1).  This approximates a 3D bar chart.

        1 column:   y        # implicit x coordinate from row number
   (2D)
        2 columns:  x  y     # line from [x,0] to [x,y]  (2D)
        3 columns:  x  y  z  # line from [x,y,0] to [x,y,z] (3D)




   3399..  LLaabbeellss


   The llaabbeellss style reads coordinates and text from a data file and
   places the text string at the corresponding 2D or 3D position.  3 or
   4 input columns of basic data are required.  Additional input col-
   umns may be used to provide information such as variable font size
   or text color (see rrggbbccoolloorr vvaarriiaabbllee).

        3 columns:  x  y  string    # 2D version
        4 columns:  x  y  z  string # 3D version

   The font, color, rotation angle and other properties of the printed
   text may be specified as additional command options (see sseett llaabbeell).
   The example below generates a 2D plot with text labels constructed
   from the city whose name is taken from column 1 of the input file,
   and whose geographic coordinates are in columns 4 and 5. The font
   size is calculated from the value in column 3, in this case the pop-
   ulation.

     CityName(String,Size) = sprintf("{/=%d %s}", Scale(Size), String)
     plot 'cities.dat' using 5:4:(CityName(stringcolumn(1),$3)) with
   labels

   If we did not want to adjust the font size to a different size for
   each city name, the command would be much simpler:

     plot 'cities.dat' using 5:4:1 with labels font "Times,8"

   The llaabbeellss style can also be used in 3D plots. In this case four
   input column specifiers are required, corresponding to X Y Z and
   text.

     splot 'datafile' using 1:2:3:4 with labels

   See also ddaattaassttrriinnggss, sseett ssttyyllee ddaattaa.



   4400..  LLiinneess













   GNUPLOT 4.1                                                       55


   The lliinneess style connects adjacent points with straight line seg-
   ments.  It may be used in either 2D or 3D plots. The basic form
   requires 1, 2, or 3 columns of input data.  Additional input columns
   may be used to provide information such as variable line color (see
   rrggbbccoolloorr vvaarriiaabbllee).

   2D form
        1 column:   y       # implicit x from row number
        2 columns:  x  y
   3D form
        1 column:   z       # implicit x from row, y from index
        3 columns:  x  y  z

   See also lliinneettyyppee, lliinneewwiiddtthh, and lliinneessttyyllee.



   4411..  LLiinneessppooiinnttss


   The lliinneessppooiinnttss style connects adjacent points with straight line
   segments and then goes back to draw a small symbol at each point.
   The command sseett ppooiinnttssiizzee may be used to change the default size of
   the points.  1 or 2 columns of basic input data are required in 2D
   plots; 1 or 3 columns are required if 3D plots.  See ssttyyllee lliinneess.
   Additional input columns may be used to provide information such as
   variable point size or line color.

   The ppooiinnttiinntteerrvvaall (short form ppii) property of the line style can be
   used to control whether or not every point in the plot is given a
   symbol.  For example, 'with lp pi 3' will draw line segments through
   every data point, but will only place a symbol on every 3rd point.
   A negative value for ppooiinnttiinntteerrvvaall will erase the portion of line
   segment that passes underneath the symbol. The size of the erased
   portion is controlled by sseett ppooiinnttiinntteerrvvaallbbooxx.

   lliinneessppooiinnttss may be abbreviated llpp.



   4422..  PPooiinnttss


   The ppooiinnttss style displays a small symbol at each point.  The command
   sseett ppooiinnttssiizzee may be used to change the default size of the points.
   1 or 2 columns of basic input data are required in 2D plots; 1 or 3
   columns are required if 3D plots.  See ssttyyllee lliinneess.  Additional
   input columns may be used to provide information such as variable
   point size or line color.














   GNUPLOT 4.1                                                       56


   4433..  SStteeppss


   The sstteeppss style is only relevant to 2D plotting.  It connects con-
   secutive points with two line segments: the first from (x1,y1) to
   (x2,y1) and the second from (x2,y1) to (x2,y2).  The input column
   requires are the same as for plot styles lliinneess and ppooiinnttss.  The dif-
   ference between ffsstteeppss and sstteeppss is that ffsstteeppss traces first the
   change in y and then the change in x.  sstteeppss traces first the change
   in x and then the change in y.  See also steps demo.




   4444..  RRggbbaallpphhaa


   See iimmaaggee.



   4455..  RRggbbiimmaaggee


   See iimmaaggee.



   4466..  VVeeccttoorrss


   The 2D vveeccttoorrss style draws a vector from (x,y) to
   (x+xdelta,y+ydelta).  The 3D vveeccttoorrss style is similar, but requires
   six columns of basic data.  A small arrowhead is drawn at the end of
   each vector.

        4 columns:  x  y  xdelta  ydelta
        6 columns:  x  y  z  xdelta  ydelta  zdelta

   splot with vectors is supported only for sseett mmaappppiinngg ccaarrtteessiiaann.  The
   keywords "with vectors" may be followed by arrow style specifica-
   tions.  See aarrrroowwssttyyllee for more details.

   Example:
         plot 'file.dat' using 1:2:3:4 with vectors head filled lt 2
         splot 'file.dat' using 1:2:3:(1):(1):(1) with vectors filled
   head lw 2

   sseett cclliipp oonnee and sseett cclliipp ttwwoo affect vectors drawn in 2D.  Please
   see sseett cclliipp and aarrrroowwssttyyllee.













   GNUPLOT 4.1                                                       57


   4477..  XXeerrrroorrbbaarrss


   The xxeerrrroorrbbaarrss style is only relevant to 2D data plots.  xxeerrrroorrbbaarrss
   is like ddoottss, except that a horizontal error bar is also drawn.  At
   each point (x,y), a line is drawn from (xlow,y) to (xhigh,y) or from
   (x-xdelta,y) to (x+xdelta,y), depending on how many data columns are
   provided.  A tic mark is placed at the ends of the error bar (unless
   sseett bbaarrss is used---see sseett bbaarrss for details).  The basic style
   requires either 3 or 4 columns:

        3 columns:  x  y  xdelta
        4 columns:  x  y  xlow  xhigh




   4488..  XXyyeerrrroorrbbaarrss


   The xxyyeerrrroorrbbaarrss style is only relevant to 2D data plots.  xxyyeerrrroorr--
   bbaarrss is like ddoottss, except that horizontal and vertical error bars
   are also drawn.  At each point (x,y), lines are drawn from (x,y-
   ydelta) to (x,y+ydelta) and from (x-xdelta,y) to (x+xdelta,y) or
   from (x,ylow) to (x,yhigh) and from (xlow,y) to (xhigh,y), depending
   upon the number of data columns provided.  A tic mark is placed at
   the ends of the error bar (unless sseett bbaarrss is used---see sseett bbaarrss
   for details).  Either 4 or 6 input columns are required.

        4 columns:  x  y  xdelta  ydelta
        6 columns:  x  y  xlow  xhigh  ylow  yhigh

   If data are provided in an unsupported mixed form, the uussiinngg filter
   on the pplloott command should be used to set up the appropriate form.
   For example, if the data are of the form (x,y,xdelta,ylow,yhigh),
   then you can use

         plot 'data' using 1:2:($1-$3):($1+$3):4:5 with xyerrorbars



   4499..  YYeerrrroorrbbaarrss


   The yyeerrrroorrbbaarrss (or eerrrroorrbbaarrss) style is only relevant to 2D data
   plots.  yyeerrrroorrbbaarrss is like ppooiinnttss, except that a vertical error bar
   is also drawn.  At each point (x,y), a line is drawn from (x,y-
   ydelta) to (x,y+ydelta) or from (x,ylow) to (x,yhigh), depending on
   how many data columns are provided.  A tic mark is placed at the
   ends of the error bar (unless sseett bbaarrss is used---see sseett bbaarrss for
   details).  Either 3 or 4 input columns are required.

        3 columns:  x  y  ydelta










   GNUPLOT 4.1                                                       58


        4 columns:  x  y  ylow  yhigh

   See also errorbar demo.



   5500..  XXeerrrroorrlliinneess


   The xxeerrrroorrlliinneess style is only relevant to 2D data plots.  xxeerrrroorr--
   lliinneess is like lliinneessppooiinnttss, except that a horizontal error line is
   also drawn. At each point (x,y), a line is drawn from (xlow,y) to
   (xhigh,y) or from (x-xdelta,y) to (x+xdelta,y), depending on how
   many data columns are provided. A tic mark is placed at the ends of
   the error bar (unless sseett bbaarrss is used---see sseett bbaarrss for details).
   The basic style requires either 3 or 4 columns:

        3 columns:  x  y  xdelta
        4 columns:  x  y  xlow  xhigh




   5511..  XXyyeerrrroorrlliinneess


   The xxyyeerrrroorrlliinneess style is only relevant to 2D data plots.  xxyyeerrrroorr--
   lliinneess is like lliinneessppooiinnttss, except that horizontal and vertical error
   bars are also drawn. At each point (x,y), lines are drawn from (x,y-
   ydelta) to (x,y+ydelta) and from (x-xdelta,y) to (x+xdelta,y) or
   from (x,ylow) to (x,yhigh) and from (xlow,y) to (xhigh,y), depending
   upon the number of data columns provided. A tic mark is placed at
   the ends of the error bar (unless sseett bbaarrss is used---see sseett bbaarrss
   for details).  Either 4 or 6 input columns are required.

        4 columns:  x  y  xdelta  ydelta
        6 columns:  x  y  xlow  xhigh  ylow  yhigh

   If data are provided in an unsupported mixed form, the uussiinngg filter
   on the pplloott command should be used to set up the appropriate form.
   For example, if the data are of the form (x,y,xdelta,ylow,yhigh),
   then you can use

         plot 'data' using 1:2:($1-$3):($1+$3):4:5 with xyerrorlines



   5522..  YYeerrrroorrlliinneess


   The yyeerrrroorrlliinneess (or eerrrroorrlliinneess) style is only relevant to 2D data
   plots. yyeerrrroorrlliinneess is like lliinneessppooiinnttss, except that a vertical error
   line is also drawn. At each point (x,y), a line is drawn from (x,y-










   GNUPLOT 4.1                                                       59


   ydelta) to (x,y+ydelta) or from (x,ylow) to (x,yhigh), depending on
   how many data columns are provided. A tic mark is placed at the ends
   of the error bar (see sseett bbaarrss for details).  Either 3 or 4 input
   columns are required.

        3 columns:  x  y  ydelta
        4 columns:  x  y  ylow  yhigh

   See also errorbar demo.



   5533..  33DD ((ssuurrffaaccee)) pplloottss


   Surface plots are generated using the sspplloott command rather than the
   pplloott command. The style wwiitthh lliinneess draws a surface made from a grid
   of lines.  Solid surfaces can be drawn using the style wwiitthh ppmm33dd.
   Usually the surface is displayed at some arbitrary viewing angle,
   such that it clearly represents a 3D surface.  In this case the X,
   Y, and Z axes are all visible in the plot. The illusion of 3D is
   enhanced by choosing hidden line removal or depth-sorted surface
   elements.  See hhiiddddeenn33dd and the ddeepptthhoorrddeerr option of sseett ppmm33dd.  The
   sspplloott command can also calculate and draw contour lines correspond-
   ing to constant Z values. These contour lines may be drawn onto the
   surface itself, or projected onto the XY plane. See sseett ccoonnttoouurr.






   An important special case of the sspplloott command is to map the Z coor-
   dinate onto a 2D surface by projecting the plot along the Z axis.
   See sseett vviieeww mmaapp.  This plot mode can be used to generate contour
   plots and heat maps.






   5544..  CCoommmmaannddss


   This section lists the commands acceptable to ggnnuupplloott in alphabeti-
   cal order.  Printed versions of this document contain all commands;
   the text available interactively may not be complete.  Indeed, on
   some systems there may be no commands at all listed under this head-
   ing.

   Note that in most cases unambiguous abbreviations for command names
   and their options are permissible, i.e., "pp ff((xx)) ww llii" instead of










   GNUPLOT 4.1                                                       60


   "pplloott ff((xx)) wwiitthh lliinneess".

   In the syntax descriptions, braces ({}) denote optional arguments
   and a vertical bar (|) separates mutually exclusive choices.



   5555..  CCdd


   The ccdd command changes the working directory.

   Syntax:
         cd '<directory-name>'

   The directory name must be enclosed in quotes.

   Examples:
         cd 'subdir'
         cd ".."

   It is recommended that Windows users use single-quotes, because
   backslash [\] has special significance inside double-quotes and has
   to be escaped.  For example,
         cd "c:\newdata"
   fails, but
         cd 'c:\newdata'
         cd "c:\\newdata"
   work as expected.



   5566..  CCaallll


   The ccaallll command is identical to the load command with one excep-
   tion: you can have up to ten additional parameters to the command
   (delimited according to the standard parser rules) which can be sub-
   stituted into the lines read from the file.  As each line is read
   from the ccaalllled input file, it is scanned for the sequence $$ (dol-
   lar-sign) followed by a digit (0--9).  If found, the sequence is
   replaced by the corresponding parameter from the ccaallll command line.
   If the parameter was specified as a string in the ccaallll line, it is
   substituted without its enclosing quotes.  Sequence $$## is replaced
   by the number of passed parameters.  $$ followed by any character
   will be that character; e.g. use $$$$ to get a single $$.  Providing
   more than ten parameters on the ccaallll command line will cause an
   error.  A parameter that was not provided substitutes as nothing.
   Files being ccaalllled may themselves contain ccaallll or llooaadd commands.

   Syntax:
         call "<input-file>" <parameter-0> <parm-1> ... <parm-9>











   GNUPLOT 4.1                                                       61


   The name of the input file must be enclosed in quotes, and it is
   recommended that parameters are similarly enclosed in quotes (future
   versions of gnuplot may treat quoted and unquoted arguments differ-
   ently).

   Example:

   If the file 'calltest.gp' contains the line:
         print "argc=$# p0=$0 p1=$1 p2=$2 p3=$3 p4=$4 p5=$5 p6=$6
   p7=x$7x"

   entering the command:
         call 'calltest.gp' "abcd" 1.2 + "'quoted'" -- "$2"

   will display:
         argc=7 p0=abcd p1=1.2 p2=+ p3='quoted' p4=- p5=- p6=$2 p7=xx

   NOTE: there is a clash in syntax with the datafile uussiinngg callback
   operator.  Use $$$$nn or ccoolluummnn((nn)) to access column n from a datafile
   inside a ccaalllled datafile plot.



   5577..  CClleeaarr


   The cclleeaarr command erases the current screen or output device as
   specified by sseett oouuttppuutt.  This usually generates a formfeed on hard-
   copy devices.  Use sseett tteerrmmiinnaall to set the device type.

   For some terminals cclleeaarr erases only the portion of the plotting
   surface defined by sseett ssiizzee, so for these it can be used in conjunc-
   tion with sseett mmuullttiipplloott to create an inset.

   Example:
         set multiplot
         plot sin(x)
         set origin 0.5,0.5
         set size 0.4,0.4
         clear
         plot cos(x)
         unset multiplot

   Please see sseett mmuullttiipplloott, sseett ssiizzee, and sseett oorriiggiinn for details of
   these commands.



   5588..  EEvvaalluuaattee


   The eevvaalluuaattee command executes the commands given as an argument
   string.  Newline characters are not allowed within the string.










   GNUPLOT 4.1                                                       62


   Syntax:
         eval <string expression>

   This is especially useful for a repetition of similar commands.

   Example:
         set_label(x, y, text) \
           = sprintf("set label '%s' at %f, %f point pt 5", text, x, y)
         eval set_label(1., 1., 'one/one')
         eval set_label(2., 1., 'two/one')
         eval set_label(1., 2., 'one/two')

   Please see ssuubbssttiittuuttiioonn mmaaccrrooss for another way to execute commands
   from a string.



   5599..  EExxiitt


   The commands eexxiitt and qquuiitt, as well as the END-OF-FILE character
   (usually Ctrl-D) terminate input from the current input stream: ter-
   minal session, pipe, and file input (pipe).

   If input streams are nested (inherited llooaadd scripts), then reading
   will continue in the parent stream. When the top level stream is
   closed, the program itself will exit.

   The command eexxiitt ggnnuupplloott will immediately and unconditionally cause
   gnuplot to exit even if the input stream is multiply nested.  In
   this case any open output files may not be completed cleanly. Exam-
   ple of use:

         bind "ctrl-x" "unset output; exit gnuplot"

   See help for bbaattcchh//iinntteerraaccttiivvee for more details.



   6600..  FFiitt


   The ffiitt command can fit a user-supplied expression to a set of data
   points (x,z) or (x,y,z), using an implementation of the nonlinear
   least-squares (NLLS) Marquardt-Levenberg algorithm.  Any user-
   defined variable occurring in the expression may serve as a fit
   parameter, but the return type of the expression must be real.

   Syntax:
         fit {<ranges>} <expression>
             '<datafile>' {datafile-modifiers}
             via '<parameter file>' | <var1>{,<var2>,...}











   GNUPLOT 4.1                                                       63


   Ranges may be specified to temporarily limit the data which is to be
   fitted; any out-of-range data points are ignored. The syntax is
         [{dummy_variable=}{<min>}{:<max>}],
   analogous to pplloott; see pplloott rraannggeess.

   <expression> is any valid ggnnuupplloott expression, although it is usual
   to use a previously user-defined function of the form f(x) or
   f(x,y).

   <datafile> is treated as in the pplloott command.  All the pplloott ddaattaaffiillee
   modifiers (uussiinngg, eevveerryy,...) except ssmmooootthh and the deprecated tthhrruu
   are applicable to ffiitt. See pplloott ddaattaaffiillee.

   The default data formats for fitting functions with a single inde-
   pendent variable, z=f(x), are z or x:z.  That is, if there is only a
   single column then it is the dependent variable and the line numbers
   is the independent variable.  If there are two columns, the first is
   the independent variable and the second is the dependent variable.

   Those formats can be changed with the datafile uussiinngg qualifier, for
   example to take the z value from a different column or to calculate
   it from several columns.  A third uussiinngg qualifier (a column number
   or an expression), if present, is interpreted as the standard devia-
   tion of the corresponding z value and is used to compute a weight
   for the datum, 1/s**2.  Otherwise, all data points are weighted
   equally, with a weight of one. Note that if you don't specify a
   uussiinngg option at all, no z standard deviations are read from the
   datafile even if it does have a third column, so you'll always get
   unit weights.

   To fit a function with two independent variables, z=f(x,y), the
   required format is uussiinngg with four items, x:y:z:s.  The complete
   format must be given---no default columns are assumed for a missing
   token.  Weights for each data point are evaluated from 's' as above.
   If error estimates are not available, a constant value can be speci-
   fied as a constant expression (see pplloott ddaattaaffiillee uussiinngg), e.g., uussiinngg
   11::22::33::((11)).

   The fit function may have up to five independent variables.  There
   must be two more uussiinngg qualifiers than there are independent vari-
   ables, unless there is only one variable.  The allowed formats, and
   the default dummy variable names, are as follows:

         z
         x:z
         x:z:s
         x:y:z:s
         x:y:t:z:s
         x:y:t:u:z:s
         x:y:t:u:v:z:s

   The dummy variable names may be changed with ranges as noted above.
   The first range corresponds to the first uussiinngg spec, etc.  A range










   GNUPLOT 4.1                                                       64


   may also be given for z (the dependent variable), but that name can-
   not be changed.

   Multiple datasets may be simultaneously fit with functions of one
   independent variable by making y a 'pseudo-variable', e.g., the
   dataline number, and fitting as two independent variables.  See ffiitt
   mmuullttii--bbrraanncchh.

   The vviiaa qualifier specifies which parameters are to be adjusted,
   either directly, or by referencing a parameter file.

   Examples:
         f(x) = a*x**2 + b*x + c
         g(x,y) = a*x**2 + b*y**2 + c*x*y
         FIT_LIMIT = 1e-6
         fit f(x) 'measured.dat' via 'start.par'
         fit f(x) 'measured.dat' using 3:($7-5) via 'start.par'
         fit f(x) './data/trash.dat' using 1:2:3 via a, b, c
         fit g(x,y) 'surface.dat' using 1:2:3:(1) via a, b, c
         fit a0 + a1*x/(1 + a2*x/(1 + a3*x)) 'measured.dat' via
   a0,a1,a2,a3
         fit a*x + b*y 'surface.dat' using 1:2:3:(1) via a,b
         fit [*:*][yaks=*:*] a*x+b*yaks 'surface.dat' u 1:2:3:(1) via
   a,b
         fit a*x + b*y + c*t 'foo.dat' using 1:2:3:4:(1) via a,b,c
         h(x,y,t,u,v) = a*x + b*y + c*t + d*u + e*v
         fit h(x,y,t,u,v) 'foo.dat' using 1:2:3:4:5:6:(1) via a,b,c,d,e

   After each iteration step, detailed information about the current
   state of the fit is written to the display.  The same information
   about the initial and final states is written to a log file,
   "fit.log".  This file is always appended to, so as to not lose any
   previous fit history;  it should be deleted or renamed as desired.
   By using the command sseett ffiitt llooggffiillee, the name of the log file can
   be changed.

   If gnuplot was built with this option, and you activated it using
   sseett ffiitt eerrrroorrvvaarriiaabblleess, the error for each fitted parameter will be
   stored in a variable named like the parameter, but with "_err"
   appended.  Thus the errors can be used as input for further computa-
   tions.

   The fit may be interrupted by pressing Ctrl-C.  After the current
   iteration completes, you have the option to (1) stop the fit and
   accept the current parameter values, (2) continue the fit, (3) exe-
   cute a ggnnuupplloott command as specified by the environment variable
   FIT_SCRIPT.  The default for FIT_SCRIPT is rreepplloott, so if you had
   previously plotted both the data and the fitting function in one
   graph, you can display the current state of the fit.

   Once ffiitt has finished, the uuppddaattee command may be used to store final
   values in a file for subsequent use as a parameter file.   See
   uuppddaattee for details.










   GNUPLOT 4.1                                                       65


        6600..11..  AAddjjuussttaabbllee ppaarraammeetteerrss


        There are two ways that vviiaa can specify the parameters to be
        adjusted, either directly on the command line or indirectly, by
        referencing a parameter file.  The two use different means to
        set initial values.

        Adjustable parameters can be specified by a comma-separated
        list of variable names after the vviiaa keyword.  Any variable
        that is not already defined is created with an initial value of
        1.0.  However, the fit is more likely to converge rapidly if
        the variables have been previously declared with more appropri-
        ate starting values.

        In a parameter file, each parameter to be varied and a corre-
        sponding initial value are specified, one per line, in the form
              varname = value

        Comments, marked by '#', and blank lines are permissible.  The
        special form
              varname = value       # FIXED

        means that the variable is treated as a 'fixed parameter', ini-
        tialized by the parameter file, but not adjusted by ffiitt.  For
        clarity, it may be useful to designate variables as fixed
        parameters so that their values are reported by ffiitt.  The key-
        word ## FFIIXXEEDD has to appear in exactly this form.




        6600..22..  SShhoorrtt iinnttrroodduuccttiioonn


        ffiitt is used to find a set of parameters that 'best' fits your
        data to your user-defined function.  The fit is judged on the
        basis of the sum of the squared differences or 'residuals'
        (SSR) between the input data points and the function values,
        evaluated at the same places.  This quantity is often called
        'chisquare' (i.e., the Greek letter chi, to the power of 2).
        The algorithm attempts to minimize SSR, or more precisely,
        WSSR, as the residuals are 'weighted' by the input data errors
        (or 1.0) before being squared; see ffiitt eerrrroorr__eessttiimmaatteess for
        details.

        That's why it is called 'least-squares fitting'.  Let's look at
        an example to see what is meant by 'non-linear', but first we
        had better go over some terms.  Here it is convenient to use z
        as the dependent variable for user-defined functions of either
        one independent variable, z=f(x), or two independent variables,
        z=f(x,y).  A parameter is a user-defined variable that ffiitt will
        adjust, i.e., an unknown quantity in the function declaration.










   GNUPLOT 4.1                                                       66


        Linearity/non-linearity refers to the relationship of the
        dependent variable, z, to the parameters which ffiitt is adjust-
        ing, not of z to the independent variables, x and/or y.  (To be
        technical, the second {and higher} derivatives of the fitting
        function with respect to the parameters are zero for a linear
        least-squares problem).

        For linear least-squares (LLS), the user-defined function will
        be a sum of simple functions, not involving any parameters,
        each multiplied by one parameter.  NLLS handles more compli-
        cated functions in which parameters can be used in a large num-
        ber of ways.  An example that illustrates the difference
        between linear and nonlinear least-squares is the Fourier
        series.  One member may be written as
             z=a*sin(c*x) + b*cos(c*x).
        If a and b are the unknown parameters and c is constant, then
        estimating values of the parameters is a linear least-squares
        problem.  However, if c is an unknown parameter, the problem is
        nonlinear.

        In the linear case, parameter values can be determined by com-
        paratively simple linear algebra, in one direct step.  However
        LLS is a special case which is also solved along with more gen-
        eral NLLS problems by the iterative procedure that ggnnuupplloott
        uses.  ffiitt attempts to find the minimum by doing a search.
        Each step (iteration) calculates WSSR with a new set of parame-
        ter values.  The Marquardt-Levenberg algorithm selects the
        parameter values for the next iteration.  The process continues
        until a preset criterion is met, either (1) the fit has "con-
        verged" (the relative change in WSSR is less than FIT_LIMIT),
        or (2) it reaches a preset iteration count limit, FIT_MAXITER
        (see ffiitt ccoonnttrrooll vvaarriiaabblleess).  The fit may also be interrupted
        and subsequently halted from the keyboard (see ffiitt).  The user
        variable FIT_CONVERGED contains 1 if the previous fit command
        terminated due to convergence; it contains 0 if the previous
        fit terminated for any other reason.

        Often the function to be fitted will be based on a model (or
        theory) that attempts to describe or predict the behaviour of
        the data.  Then ffiitt can be used to find values for the free
        parameters of the model, to determine how well the data fits
        the model, and to estimate an error range for each parameter.
        See ffiitt eerrrroorr__eessttiimmaatteess.

        Alternatively, in curve-fitting, functions are selected inde-
        pendent of a model (on the basis of experience as to which are
        likely to describe the trend of the data with the desired reso-
        lution and a minimum number of parameters*functions.)  The ffiitt
        solution then provides an analytic representation of the curve.

        However, if all you really want is a smooth curve through your
        data points, the ssmmooootthh option to pplloott may be what you've been
        looking for rather than ffiitt.










   GNUPLOT 4.1                                                       67


        6600..33..  EErrrroorr eessttiimmaatteess


        In ffiitt, the term "error" is used in two different contexts,
        data error estimates and parameter error estimates.

        Data error estimates are used to calculate the relative weight
        of each data point when determining the weighted sum of squared
        residuals, WSSR or chisquare.  They can affect the parameter
        estimates, since they determine how much influence the devia-
        tion of each data point from the fitted function has on the
        final values.  Some of the ffiitt output information, including
        the parameter error estimates, is more meaningful if accurate
        data error estimates have been provided.

        The 'statistical overview' describes some of the ffiitt output and
        gives some background for the 'practical guidelines'.




             6600..33..11..  SSttaattiissttiiccaall oovveerrvviieeww


             The theory of non-linear least-squares (NLLS) is generally
             described in terms of a normal distribution of errors,
             that is, the input data is assumed to be a sample from a
             population having a given mean and a Gaussian (normal)
             distribution about the mean with a given standard devia-
             tion.  For a sample of sufficiently large size, and know-
             ing the population standard deviation, one can use the
             statistics of the chisquare distribution to describe a
             "goodness of fit" by looking at the variable often called
             "chisquare".  Here, it is sufficient to say that a reduced
             chisquare (chisquare/degrees of freedom, where degrees of
             freedom is the number of datapoints less the number of
             parameters being fitted) of 1.0 is an indication that the
             weighted sum of squared deviations between the fitted
             function and the data points is the same as that expected
             for a random sample from a population characterized by the
             function with the current value of the parameters and the
             given standard deviations.

             If the standard deviation for the population is not con-
             stant, as in counting statistics where variance = counts,
             then each point should be individually weighted when com-
             paring the observed sum of deviations and the expected sum
             of deviations.

             At the conclusion ffiitt reports 'stdfit', the standard devi-
             ation of the fit, which is the rms of the residuals, and
             the variance of the residuals, also called 'reduced
             chisquare' when the data points are weighted.  The number










   GNUPLOT 4.1                                                       68


             of degrees of freedom (the number of data points minus the
             number of fitted parameters) is used in these estimates
             because the parameters used in calculating the residuals
             of the datapoints were obtained from the same data.  These
             values are exported to the variables
                   FIT_NDF = Number of degrees of freedom
                   FIT_WSSR = Weighted sum-of-squares residual
                   FIT_STDFIT = sqrt(WSSR/NDF)

             To estimate confidence levels for the parameters, one can
             use the minimum chisquare obtained from the fit and
             chisquare statistics to determine the value of chisquare
             corresponding to the desired confidence level, but consid-
             erably more calculation is required to determine the com-
             binations of parameters which produce such values.

             Rather than determine confidence intervals, ffiitt reports
             parameter error estimates which are readily obtained from
             the variance-covariance matrix after the final iteration.
             By convention, these estimates are called "standard
             errors" or "asymptotic standard errors", since they are
             calculated in the same way as the standard errors (stan-
             dard deviation of each parameter) of a linear least-
             squares problem, even though the statistical conditions
             for designating the quantity calculated to be a standard
             deviation are not generally valid for the NLLS problem.
             The asymptotic standard errors are generally over-opti-
             mistic and should not be used for determining confidence
             levels, but are useful for qualitative purposes.

             The final solution also produces a correlation matrix,
             which gives an indication of the correlation of parameters
             in the region of the solution; if one parameter is
             changed, increasing chisquare, does changing another com-
             pensate?  The main diagonal elements, autocorrelation, are
             all 1; if all parameters were independent, all other ele-
             ments would be nearly 0.  Two variables which completely
             compensate each other would have an off-diagonal element
             of unit magnitude, with a sign depending on whether the
             relation is proportional or inversely proportional.  The
             smaller the magnitudes of the off-diagonal elements, the
             closer the estimates of the standard deviation of each
             parameter would be to the asymptotic standard error.



             6600..33..22..  PPrraaccttiiccaall gguuiiddeelliinneess


             If you have a basis for assigning weights to each data
             point, doing so lets you make use of additional knowledge
             about your measurements, e.g., take into account that some
             points may be more reliable than others.  That may affect










   GNUPLOT 4.1                                                       69


             the final values of the parameters.

             Weighting the data provides a basis for interpreting the
             additional ffiitt output after the last iteration.  Even if
             you weight each point equally, estimating an average stan-
             dard deviation rather than using a weight of 1 makes WSSR
             a dimensionless variable, as chisquare is by definition.

             Each fit iteration will display information which can be
             used to evaluate the progress of the fit.  (An '*' indi-
             cates that it did not find a smaller WSSR and is trying
             again.)  The 'sum of squares of residuals', also called
             'chisquare', is the WSSR between the data and your fitted
             function; ffiitt has minimized that.  At this stage, with
             weighted data, chisquare is expected to approach the num-
             ber of degrees of freedom (data points minus parameters).
             The WSSR can be used to calculate the reduced chisquare
             (WSSR/ndf) or stdfit, the standard deviation of the fit,
             sqrt(WSSR/ndf).  Both of these are reported for the final
             WSSR.

             If the data are unweighted, stdfit is the rms value of the
             deviation of the data from the fitted function, in user
             units.

             If you supplied valid data errors, the number of data
             points is large enough, and the model is correct, the
             reduced chisquare should be about unity.  (For details,
             look up the 'chi-squared distribution' in your favourite
             statistics reference.)  If so, there are additional tests,
             beyond the scope of this overview, for determining how
             well the model fits the data.

             A reduced chisquare much larger than 1.0 may be due to
             incorrect data error estimates, data errors not normally
             distributed, systematic measurement errors, 'outliers', or
             an incorrect model function.  A plot of the residuals,
             e.g., pplloott ''ddaattaaffiillee'' uussiinngg 11::(($$22--ff(($$11)))), may help to show
             any systematic trends.  Plotting both the data points and
             the function may help to suggest another model.

             Similarly, a reduced chisquare less than 1.0 indicates
             WSSR is less than that expected for a random sample from
             the function with normally distributed errors.  The data
             error estimates may be too large, the statistical assump-
             tions may not be justified, or the model function may be
             too general, fitting fluctuations in a particular sample
             in addition to the underlying trends.  In the latter case,
             a simpler function may be more appropriate.

             You'll have to get used to both ffiitt and the kind of prob-
             lems you apply it to before you can relate the standard
             errors to some more practical estimates of parameter










   GNUPLOT 4.1                                                       70


             uncertainties or evaluate the significance of the correla-
             tion matrix.

             Note that ffiitt, in common with most NLLS implementations,
             minimizes the weighted sum of squared distances (y-
             f(x))**2.  It does not provide any means to account for
             "errors" in the values of x, only in y.  Also, any "out-
             liers" (data points outside the normal distribution of the
             model) will have an exaggerated effect on the solution.



        6600..44..  CCoonnttrrooll


        There are a number of ggnnuupplloott variables that can be defined to
        affect ffiitt.  Those which can be defined once ggnnuupplloott is running
        are listed under 'control_variables' while those defined before
        starting ggnnuupplloott are listed under 'environment_variables'.




             6600..44..11..  CCoonnttrrooll vvaarriiaabblleess


             The default epsilon limit (1e-5) may be changed by declar-
             ing a value for
                   FIT_LIMIT
             When the sum of squared residuals changes between two
             iteration steps by a factor less than this number
             (epsilon), the fit is considered to have 'converged'.

             The maximum number of iterations may be limited by declar-
             ing a value for
                   FIT_MAXITER
             A value of 0 (or not defining it at all)  means that there
             is no limit.

             If you need even more control about the algorithm, and
             know the Marquardt-Levenberg algorithm well, there are
             some more variables to influence it. The startup value of
             llaammbbddaa is normally calculated automatically from the ML-
             matrix, but if you want to, you may provide your own one
             with
                   FIT_START_LAMBDA
             Specifying FIT_START_LAMBDA as zero or less will re-enable
             the automatic selection. The variable
                   FIT_LAMBDA_FACTOR
             gives the factor by which llaammbbddaa is increased or decreased
             whenever the chi-squared target function increased or
             decreased significantly.  Setting FIT_LAMBDA_FACTOR to
             zero re-enables the default factor of 10.0.










   GNUPLOT 4.1                                                       71


             Other variables with the FIT_ prefix may be added to ffiitt,
             so it is safer not to use that prefix for user-defined
             variables.

             The variables FIT_SKIP and FIT_INDEX were used by earlier
             releases of ggnnuupplloott with a 'fit' patch called ggnnuuffiitt and
             are no longer available.  The datafile eevveerryy modifier pro-
             vides the functionality of FIT_SKIP.  FIT_INDEX was used
             for multi-branch fitting, but multi-branch fitting of one
             independent variable is now done as a pseudo-3D fit in
             which the second independent variable and uussiinngg are used
             to specify the branch.  See ffiitt mmuullttii--bbrraanncchh.



             6600..44..22..  EEnnvviirroonnmmeenntt vvaarriiaabblleess


             The environment variables must be defined before ggnnuupplloott
             is executed; how to do so depends on your operating sys-
             tem.

                   FIT_LOG
             changes the name (and/or path) of the file to which the
             fit log will be written from the default of "fit.log" in
             the working directory. The default value can be overwrit-
             ten using the command sseett ffiitt llooggffiillee.

                   FIT_SCRIPT
             specifies a command that may be executed after an user
             interrupt. The default is rreepplloott, but a pplloott or llooaadd com-
             mand may be useful to display a plot customized to high-
             light the progress of the fit.



        6600..55..  MMuullttii--bbrraanncchh


        In multi-branch fitting, multiple data sets can be simultane-
        ously fit with functions of one independent variable having
        common parameters by minimizing the total WSSR.  The function
        and parameters (branch) for each data set are selected by using
        a 'pseudo-variable', e.g., either the dataline number (a 'col-
        umn' index of -1) or the datafile index (-2), as the second
        independent variable.

        Example:  Given two exponential decays of the form, z=f(x),
        each describing a different data set but having a common decay
        time, estimate the values of the parameters.  If the datafile
        has the format x:z:s, then
             f(x,y) = (y==0) ? a*exp(-x/tau) : b*exp(-x/tau)
             fit f(x,y) 'datafile' using  1:-2:2:3  via a, b, tau










   GNUPLOT 4.1                                                       72


        For a more complicated example, see the file "hexa.fnc" used by
        the "fit.dem" demo.

        Appropriate weighting may be required since unit weights may
        cause one branch to predominate if there is a difference in the
        scale of the dependent variable.  Fitting each branch sepa-
        rately, using the multi-branch solution as initial values, may
        give an indication as to the relative effect of each branch on
        the joint solution.



        6600..66..  SSttaarrttiinngg vvaalluueess


        Nonlinear fitting is not guaranteed to converge to the global
        optimum (the solution with the smallest sum of squared residu-
        als, SSR), and can get stuck at a local minimum.  The routine
        has no way to determine that;  it is up to you to judge whether
        this has happened.

        ffiitt may, and often will get "lost" if started far from a solu-
        tion, where SSR is large and changing slowly as the parameters
        are varied, or it may reach a numerically unstable region
        (e.g., too large a number causing a floating point overflow)
        which results in an "undefined value" message or ggnnuupplloott halt-
        ing.

        To improve the chances of finding the global optimum, you
        should set the starting values at least roughly in the vicinity
        of the solution, e.g., within an order of magnitude, if possi-
        ble.  The closer your starting values are to the solution, the
        less chance of stopping at another minimum.  One way to find
        starting values is to plot data and the fitting function on the
        same graph and change parameter values and rreepplloott until reason-
        able similarity is reached.  The same plot is also useful to
        check whether the fit stopped at a minimum with a poor fit.

        Of course, a reasonably good fit is not proof there is not a
        "better" fit (in either a statistical sense, characterized by
        an improved goodness-of-fit criterion, or a physical sense,
        with a solution more consistent with the model.)  Depending on
        the problem, it may be desirable to ffiitt with various sets of
        starting values, covering a reasonable range for each parame-
        ter.



        6600..77..  TTiippss


        Here are some tips to keep in mind to get the most out of ffiitt.
        They're not very organized, so you'll have to read them several










   GNUPLOT 4.1                                                       73


        times until their essence has sunk in.

        The two forms of the vviiaa argument to ffiitt serve two largely dis-
        tinct purposes.  The vviiaa ""ffiillee"" form is best used for (possibly
        unattended) batch operation, where you just supply the startup
        values in a file and can later use uuppddaattee to copy the results
        back into another (or the same) parameter file.

        The vviiaa vvaarr11,, vvaarr22,, ...... form is best used interactively, where
        the command history mechanism may be used to edit the list of
        parameters to be fitted or to supply new startup values for the
        next try.  This is particularly useful for hard problems, where
        a direct fit to all parameters at once won't work without good
        starting values.  To find such, you can iterate several times,
        fitting only some of the parameters, until the values are close
        enough to the goal that the final fit to all parameters at once
        will work.

        Make sure that there is no mutual dependency among parameters
        of the function you are fitting.  For example, don't try to fit
        a*exp(x+b), because a*exp(x+b)=a*exp(b)*exp(x).  Instead, fit
        either a*exp(x) or exp(x+b).

        A technical issue:  the parameters must not be too different in
        magnitude.  The larger the ratio of the largest and the small-
        est absolute parameter values, the slower the fit will con-
        verge.  If the ratio is close to or above the inverse of the
        machine floating point precision, it may take next to forever
        to converge, or refuse to converge at all.  You will have to
        adapt your function to avoid this, e.g., replace 'parameter' by
        '1e9*parameter' in the function definition, and divide the
        starting value by 1e9.

        If you can write your function as a linear combination of sim-
        ple functions weighted by the parameters to be fitted, by all
        means do so.  That helps a lot, because the problem is no
        longer nonlinear and should converge with only a small number
        of iterations, perhaps just one.

        Some prescriptions for analysing data, given in practical
        experimentation courses, may have you first fit some functions
        to your data, perhaps in a multi-step process of accounting for
        several aspects of the underlying theory one by one, and then
        extract the information you really wanted from the fitting
        parameters of those functions.  With ffiitt, this may often be
        done in one step by writing the model function directly in
        terms of the desired parameters.  Transforming data can also
        quite often be avoided, though sometimes at the cost of a more
        difficult fit problem.  If you think this contradicts the pre-
        vious paragraph about simplifying the fit function, you are
        correct.

        A "singular matrix" message indicates that this implementation










   GNUPLOT 4.1                                                       74


        of the Marquardt-Levenberg algorithm can't calculate parameter
        values for the next iteration.  Try different starting values,
        writing the function in another form, or a simpler function.

        Finally, a nice quote from the manual of another fitting pack-
        age (fudgit), that kind of summarizes all these issues:  "Non-
        linear fitting is an art!"



   6611..  HHeellpp


   The hheellpp command displays built-in help. To specify information on a
   particular topic use the syntax:

         help {<topic>}

   If <topic> is not specified, a short message is printed about ggnnuu--
   pplloott.  After help for the requested topic is given, a menu of
   subtopics is given; help for a subtopic may be requested by typing
   its name, extending the help request.  After that subtopic has been
   printed, the request may be extended again or you may go back one
   level to the previous topic.  Eventually, the ggnnuupplloott command line
   will return.

   If a question mark (?) is given as the topic, the list of topics
   currently available is printed on the screen.



   6622..  HHiissttoorryy


   hhiissttoorryy command lists or saves previous entries in the history of
   the command line editing, or executes an entry.

   Here you find 'usage by examples':

         history               # show the complete history
         history 5             # show last 5 entries in the history
         history quiet 5       # show last 5 entries without entry num-
   bers
         history "hist.gp"     # write the complete history to file
   hist.gp
         history "hist.gp" append # append the complete history to file
   hist.gp
         history 10 "hist.gp"  # write last 10 commands to file hist.gp
         history 10 "|head -5 >>diary.gp" # write 5 history commands
   using pipe
         history ?load         # show all history entries starting with
   "load"
         history ?"set c"      # like above, several words enclosed in










   GNUPLOT 4.1                                                       75


   quotes
         hi !reread            # execute last entry starting with
   "reread"
         hist !"set xr"        # like above, several words enclosed in
   quotes
         hi !hi                # guess yourself :-))

   On systems which support a popen function (Unix), the output of his-
   tory can be piped through an external program by starting the file
   name with a '|', as one of the above examples demonstrates.



   6633..  IIff


   The iiff command allows commands to be executed conditionally.

   Syntax:
         if (<condition>) <command-line> [; else if (<condition>) ...;
   else ...]

   <condition> will be evaluated.  If it is true (non-zero), then the
   command(s) of the <command-line> will be executed.  If <condition>
   is false (zero), then the entire <command-line> is ignored until the
   next occurrence of eellssee.  Note that use of ;; to allow multiple com-
   mands on the same line will _not_ end the conditionalized commands.

   Examples:
         pi=3
         if (pi!=acos(-1)) print "?Fixing pi!"; pi=acos(-1); print pi
   will display:
         ?Fixing pi!
         3.14159265358979
   but
         if (1==2) print "Never see this"; print "Or this either"
   will not display anything.

   else:
         v=0
         v=v+1; if (v%2) print "2" ; else if (v%3) print "3"; else
   print "fred"
   (repeat the last line repeatedly!)

   See rreerreeaadd for an example of how iiff and rreerreeaadd can be used together
   to perform a loop.



   6644..  IItteerraattiioonn













   GNUPLOT 4.1                                                       76


   The pplloott, sspplloott, sseett and uunnsseett commands may optionally contain an
   iteration clause.  This has the effect of executing the basic com-
   mand multiple times, each time re-evaluating any expressions that
   make use of the iteration control variable.  Two forms of iteration
   clause are currently supported:

         for [intvar = start:end{:increment}]
         for [stringvar in "A B C D"]

   Examples:

         plot for [filename in "A.dat B.dat C.dat"] filename using 1:2
   with lines
         plot for [basename in "A B C"] basename.".dat" using 1:2 with
   lines
         set for [i = 1:10] style line i lc rgb "blue"
         unset for [tag = 100:200] label tag

   See additional documentation for pplloott iitteerraattiioonn.




   6655..  LLooaadd


   The llooaadd command executes each line of the specified input file as
   if it had been typed in interactively.  Files created by the ssaavvee
   command can later be llooaadded.  Any text file containing valid com-
   mands can be created and then executed by the llooaadd command.  Files
   being llooaadded may themselves contain llooaadd or ccaallll commands.  See ccoomm--
   mmeennttss for information about comments in commands.  To llooaadd with
   arguments, see ccaallll.

   Syntax:
         load "<input-file>"

   The name of the input file must be enclosed in quotes.

   The special filename "-" may be used to llooaadd commands from standard
   input.  This allows a ggnnuupplloott command file to accept some commands
   from standard input.  Please see help for bbaattcchh//iinntteerraaccttiivvee for more
   details.

   On some systems which support a popen function (Unix), the load file
   can be read from a pipe by starting the file name with a '<'.

   Examples:
         load 'work.gnu'
         load "func.dat"
         load "< loadfile_generator.sh"

   The llooaadd command is performed implicitly on any file names given as










   GNUPLOT 4.1                                                       77


   arguments to ggnnuupplloott.  These are loaded in the order specified, and
   then ggnnuupplloott exits.



   6666..  LLoowweerr


   Syntax:
         lower {plot_window_nb}

   The lloowweerr command lowers (opposite to rraaiissee) plot window(s) associ-
   ated with the interactive terminal of your gnuplot session, i.e. ppmm,
   wwiinn, wwxxtt or xx1111. It puts the plot window to bottom in the z-order
   windows stack of the window manager of your desktop.

   As xx1111 and wwxxtt support multiple plot windows, then by default they
   lower these windows in descending order of most recently created on
   top to the least recently created on bottom. If a plot number is
   supplied as an optional parameter, only the associated plot window
   will be lowered if it exists.

   The optional parameter is ignored for single plot-window terminals,
   i.e. ppmm and wwiinn.



   6677..  PPaauussee


   The ppaauussee command displays any text associated with the command and
   then waits a specified amount of time or until the carriage return
   is pressed.  ppaauussee is especially useful in conjunction with llooaadd
   files.

   Syntax:
         pause <time> {"<string>"}
         pause mouse {<endcondition>}{, <endcondition>} {"<string>"}

   <time> may be any constant or expression.  Choosing -1 will wait
   until a carriage return is hit, zero (0) won't pause at all, and a
   positive number will wait the specified number of seconds.  The time
   is rounded to an integer number of seconds if subsecond time resolu-
   tion is not supported by the given platform.  ppaauussee 00 is synonymous
   with pprriinntt.

   If the current terminal supports mmoouussiinngg, then ppaauussee mmoouussee will ter-
   minate on either a mouse click or on ctrl-C.  For all other termi-
   nals, or if mousing is not active, ppaauussee mmoouussee is equivalent to
   ppaauussee --11.

   If one or more end conditions are given after ppaauussee mmoouussee, then any
   one of the conditions will terminate the pause. The possible end










   GNUPLOT 4.1                                                       78


   conditions are kkeeyypprreessss, bbuuttttoonn11, bbuuttttoonn22, bbuuttttoonn33, cclloossee, and aannyy.
   If the pause terminates on a keypress, then the ascii value of the
   key pressed is returned in MOUSE_KEY.  The character itself is
   returned as a one character string in MOUSE_CHAR. Hotkeys (bind com-
   mand) are disabled if keypress is one of the end conditions.  Zoom-
   ing is disabled if button3 is one of the end conditions.

   In all cases the coordinates of the mouse are returned in variables
   MOUSE_X, MOUSE_Y, MOUSE_X2, MOUSE_Y2.  See mmoouussee vvaarriiaabblleess.

   Note: Since ppaauussee communicates with the operating system rather than
   the graphics, it may behave differently with different device driv-
   ers (depending upon how text and graphics are mixed).

   Examples:
         pause -1    # Wait until a carriage return is hit
         pause 3     # Wait three seconds
         pause -1  "Hit return to continue"
         pause 10  "Isn't this pretty?  It's a cubic spline."
         pause mouse "Click any mouse button on selected data point"
         pause mouse keypress "Type a letter from A-F in the active
   window"
         pause mouse button1,keypress
         pause mouse any "Any key or button will terminate"

   The variant "pause mouse key" will resume after any keypress in the
   active plot window. If you want to wait for a particular key to be
   pressed, you can use a reread loop such as:

         print "I will resume after you hit the Tab key in the plot
   window"
         load "wait_for_tab"

   File "wait_for_tab" contains the lines

         pause mouse key
         if (MOUSE_KEY != 9) reread




   6688..  PPlloott


   pplloott is the primary command for drawing plots with ggnnuupplloott.  It cre-
   ates plots of functions and data in many, many ways.  pplloott is used
   to draw 2-d functions and data; sspplloott draws 2D projections of 3D
   surfaces and data.  pplloott and sspplloott contain many common features; see
   sspplloott for differences.  Note specifically that although the bbiinnaarryy
   <<bbiinnaarryy lliisstt>> variation does work for both pplloott and sspplloott, there are
   small differences between these modes.

   Syntax:










   GNUPLOT 4.1                                                       79


         plot {<ranges>}
              {<iteration>}
              {<function> | {"<datafile>" {datafile-modifiers}}}
              {axes <axes>} {<title-spec>} {with <style>}
              {, {definitions{,}} <function> ...}

   where either a <function> or the name of a data file enclosed in
   quotes is supplied.  A function is a mathematical expression or a
   pair of mathematical expressions in parametric mode.  The expres-
   sions may be defined completely or in part earlier in the stream of
   ggnnuupplloott commands (see uusseerr--ddeeffiinneedd).

   It is also possible to define functions and parameters on the pplloott
   command itself.  This is done merely by isolating them from other
   items with commas.

   Examples:
         plot sin(x)
         plot sin(x), cos(x)
         plot f(x) = sin(x*a), a = .2, f(x), a = .4, f(x)
         plot "datafile.1" with lines, "datafile.2" with points
         plot [t=1:10] [-pi:pi*2] tan(t), \
              "data.1" using (tan($2)):($3/$4) smooth csplines \
                       axes x1y2 notitle with lines 5
         plot for [datafile in "spinach.dat broccoli.dat"] datafile

   See also sshhooww pplloott.




        6688..11..  AAxxeess


        There are four possible sets of axes available; the keyword
        <axes> is used to select the axes for which a particular line
        should be scaled.  xx11yy11 refers to the axes on the bottom and
        left; xx22yy22 to those on the top and right; xx11yy22 to those on the
        bottom and right; and xx22yy11 to those on the top and left.
        Ranges specified on the pplloott command apply only to the first
        set of axes (bottom left).



        6688..22..  DDaattaa


        Discrete data contained in a file can be displayed by specify-
        ing the name of the data file (enclosed in single or double
        quotes) on the pplloott command line.

        Syntax:
              plot '<file_name>' {binary <binary list>}










   GNUPLOT 4.1                                                       80


                                 {{nonuniform} matrix}
                                 {index <index list> | index "<name>"}
                                 {every <every list>}
                                 {thru <thru expression>}
                                 {using <using list>}
                                 {smooth <option>}
                                 {volatile} {noautoscale}

        The modifiers bbiinnaarryy, iinnddeexx, eevveerryy, tthhrruu, uussiinngg, and ssmmooootthh are
        discussed separately.  In brief, bbiinnaarryy allows data entry from
        a binary file (default is ASCII), iinnddeexx selects which data sets
        in a multi-data-set file are to be plotted, eevveerryy specifies
        which points within a single data set are to be plotted, uussiinngg
        determines how the columns within a single record are to be
        interpreted (tthhrruu is a special case of uussiinngg), and ssmmooootthh
        allows for simple interpolation and approximation.  (sspplloott has
        a similar syntax, but does not support the ssmmooootthh and tthhrruu
        options.)

        The vvoollaattiillee keyword indicates that the contents of the data
        file may be different if the file is re-read.  This tells the
        program to use rreeffrreesshh rather than rreepplloott commands whenever
        possible.  See rreeffrreesshh.

        The nnooaauuttoossccaallee keyword means that the points making up this
        plot will be ignored when automatically determining axis range
        limits.


        ASCII DATA FILES:

        Data files should contain at least one data point per record
        (uussiinngg can select one data point from the record). Records
        beginning with ## (and also with !! on VMS) will be treated as
        comments and ignored.  Each data point represents an (x,y)
        pair. For ppllootts with error bars or error bars with lines (see
        sseett ssttyyllee eerrrroorrbbaarrss or sseett ssttyyllee eerrrroorrlliinneess), each data point
        is (x,y,ydelta), (x,y,ylow,yhigh), (x,y,xdelta),
        (x,y,xlow,xhigh), or (x,y,xlow,xhigh,ylow,yhigh).

        In all cases, the numbers of each record of a data file must be
        separated by white space (one or more blanks or tabs) unless a
        format specifier is provided by the uussiinngg option. This white
        space divides each record into columns. However, whitespace
        inside a pair of double quotes is ignored when counting col-
        umns, so the following datafile line has three columns:
              1.0 "second column" 3.0

        Data may be written in exponential format with the exponent
        preceded by the letter e or E.  The fortran exponential speci-
        fiers d, D, q, and Q may also be used if the command sseett
        ddaattaaffiillee ffoorrttrraann is in effect.











   GNUPLOT 4.1                                                       81


        Only one column (the y value) need be provided.  If x is omit-
        ted, ggnnuupplloott provides integer values starting at 0.

        In datafiles, blank records (records with no characters other
        than blanks and a newline and/or carriage return) are signifi-
        cant.

        Single blank records designate discontinuities in a pplloott; no
        line will join points separated by a blank records (if they are
        plotted with a line style).

        Two blank records in a row indicate a break between separate
        data sets.  See iinnddeexx.

        If autoscaling has been enabled (sseett aauuttoossccaallee), the axes are
        automatically extended to include all datapoints, with a whole
        number of tic marks if tics are being drawn.  This has two con-
        sequences: i) For sspplloott, the corner of the surface may not
        coincide with the corner of the base.  In this case, no verti-
        cal line is drawn.  ii) When plotting data with the same x
        range on a dual-axis graph, the x coordinates may not coincide
        if the x2tics are not being drawn.  This is because the x axis
        has been autoextended to a whole number of tics, but the x2
        axis has not.  The following example illustrates the problem:

              reset; plot '-', '-' axes x2y1
              1 1
              19 19
              e
              1 1
              19 19
              e

        To avoid this, you can use the ffiixxmmiinn/ffiixxmmaaxx feature of the sseett
        aauuttoossccaallee command, which turns off the automatic extension of
        the axis range upto the next tic mark.

        Label coordinates and text can also be read from a data file
        (see llaabbeellss).


        BINARY DATA FILES:

        Gnuplot can read binary data files.  However, adequate informa-
        tion about details of the file format must be given on the com-
        mand line or extracted from the file itself for a supported
        binary ffiilleettyyppee.  In particular, there are two structures for
        binary files, a matrix binary format and a general binary for-
        mat.

        The matrix binary format contains a two dimensional array of 32
        bit IEEE float values with an additional column and row of
        coordinate values.  As with ASCII matrix, in the uussiinngg list,










   GNUPLOT 4.1                                                       82


        repetition of the coordinate row constitutes column 1, repeti-
        tion of the coordinate column constitutes column 2, and the
        array of values constitutes column 3.

        The general binary format contains an arbitrary number of col-
        umns for which information must be specified at the command
        line.  For example, aarrrraayy, rreeccoorrdd, ffoorrmmaatt and uussiinngg can indi-
        cate the size, format and dimension of data.  There are a vari-
        ety of useful commands for skipping file headers and changing
        endianess.  There are a set of commands for positioning and
        translating data since often coordinates are not part of the
        file when uniform sampling is inherent in the data.  Different
        from matrix binary or ASCII, general binary does not treat the
        generated columns as 1, 2 or 3 in the uussiinngg list.  Rather, col-
        umn 1 begins with column 1 of the file, or as specified in the
        ffoorrmmaatt list.

        There are global default settings for the various binary
        options which may be set using the same syntax as the options
        when used as part of the ((ss))pplloott <<ffiilleennaammee>> bbiinnaarryy ...... command.
        This syntax is sseett ddaattaaffiillee bbiinnaarryy .......  The general rule is
        that common command-line specified parameters override file-
        extracted parameters which override default parameters.

        Matrix binary is the default binary format when no keywords
        specific to general binary are given, i.e., aarrrraayy, rreeccoorrdd, ffoorr--
        mmaatt, ffiilleettyyppee.

        General binary data can be entered at the command line via the
        special file name '-'.  However, this is intended for use
        through a pipe where programs can exchange binary data, not for
        keyboards.  There is no "end of record" character for binary
        data.  Gnuplot continues reading from a pipe until it has read
        the number of points declared in the aarrrraayy qualifier.

        See ddaattaaffiillee bbiinnaarryy for more details.




             6688..22..11..  BBiinnaarryy


             The bbiinnaarryy keyword allows a data file to be binary as
             opposed to ASCII.  There are two formats for
             binary--matrix binary and general binary.  Matrix binary
             is a fixed format in which data appears in a 2D array with
             an extra row and column for coordinate values.  General
             binary is a flexible format for which details about the
             file must be given at the command line.

             See bbiinnaarryy mmaattrriixx or bbiinnaarryy ggeenneerraall for more details.











   GNUPLOT 4.1                                                       83


             6688..22..22..  BBiinnaarryy ggeenneerraall


             General binary data in which format information is not
             necessarily part of the file can be read by giving further
             details about the file format at the command line.
             Although the syntax is slightly arcane to the casual user,
             general binary is particularly useful for application pro-
             grams using gnuplot and sending large amounts of data.

             Syntax:
                   plot '<file_name>' {binary <binary list>} ...
                   splot '<file_name>' {binary <binary list>} ...

             General binary format is activated by keywords in <binary
             list> pertaining to information about file structure,
             i.e., aarrrraayy, rreeccoorrdd, ffoorrmmaatt or ffiilleettyyppee.  Otherwise,
             matrix binary format is assumed.  (See bbiinnaarryy mmaattrriixx for
             more details.)

             There are some standard file types that may be read for
             which details about the binary format may be extracted
             automatically.  (Type sshhooww ddaattaaffiillee bbiinnaarryy at the command
             line for a list.)  Otherwise, details must be specified at
             the command line or set in the defaults.  Keywords are
             described below.

             The keyword ffiilleettyyppee in <binary list> controls the routine
             used to read the file, i.e., the format of the data.  For
             a list of the supported file types, type sshhooww ddaattaaffiillee
             bbiinnaarryy ffiilleettyyppeess.  If no file type is given, the rule is
             that traditional gnuplot binary is assumed for sspplloott if
             the bbiinnaarryy keyword stands alone.  In all other circum-
             stances, for pplloott or when one of the <binary list> key-
             words appears, a raw binary file is assumed whereby the
             keywords specify the binary format.

             General binary data files fall into two basic classes, and
             some files may be of both classes depending upon how they
             are treated.  There is that class for which uniform sam-
             pling is assumed and point coordinates must be generated.
             This is the class for which full control via the <binary
             list> keywords applies.  For this class, the settings
             precedence is that command line parameters override in-
             file parameters, which override default settings.  The
             other class is that set of files for which coordinate
             information is contained within the file or there is pos-
             sibly a non-uniform sampling such as gnuplot binary.

             Other than for the unique data files such as gnuplot
             binary, one should think of binary data as conceptually
             the same as ASCII data.  Each point has columns of infor-
             mation which are selected via the <<uussiinngg lliisstt>> associated










   GNUPLOT 4.1                                                       84


             with uussiinngg.  When no ffoorrmmaatt string is specified, gnuplot
             will retrieve a number of binary variables equal to the
             largest column given in the <<uussiinngg lliisstt>>.  For example,
             uussiinngg 11::33 will result in three columns being read, of
             which the second will be ignored.  There are default using
             lists based upon the typical number of parameters associ-
             ated with a certain plot type.  For example, wwiitthh iimmaaggee
             has a default of uussiinngg 11, while wwiitthh rrggbbiimmaaggee has a
             default of uussiinngg 11::22::33.  Note that the special characters
             for uussiinngg representing point/line/index generally should
             not be used for binary data.  There are keywords in
             <binary list> that control this.



             6688..22..33..  AArrrraayy


             Describes the sampling array dimensions associated with
             the binary file.  The coordinates will be generated by
             gnuplot.  A number must be specified for each dimension of
             the array.  For example, aarrrraayy==((1100,,2200)) means the underly-
             ing sampling structure is two-dimensional with 10 points
             along the first (x) dimension and 20 points along the sec-
             ond (y) dimension.  A negative number indicates that data
             should be read until the end of file.  If there is only
             one dimension, the parentheses may be omitted.  A colon
             can be used to separate the dimensions for multiple
             records.  For example, aarrrraayy==2255::3355 indicates there are two
             one-dimensional records in the file.
                   Note:  Gnuplot version 4.2 used the syntax
             array=128x128 rather than
                          array=(128,128). The older syntax is now dep-
             recated, but may
                          still work if your copy of gnuplot was built
             to support
                          backwards compatibility.



             6688..22..44..  RReeccoorrdd


             This keyword serves the same function as aarrrraayy, having the
             same syntax.  However, rreeccoorrdd causes gnuplot to not gener-
             ate coordinate information.  This is for the case where
             such information may be included in one of the columns of
             the binary data file.















   GNUPLOT 4.1                                                       85


             6688..22..55..  SSkkiipp


             This keyword allows you to skip sections of a binary file.
             For instance, if the file contains a 1024 byte header
             before the start of the data region you would probably
             want to use
                   plot '<file_name>' binary skip=1024 ...
             If there are multiple records in the file, you may specify
             a leading offset for each. For example, to skip 512 bytes
             before the 1st record and 256 bytes before the second and
             third records
                   plot '<file_name> binary record=356:356:356
             skip=512:256:256 ...



             6688..22..66..  FFoorrmmaatt


             The default binary format is a float.  For more flexibil-
             ity, the format can include details about variable sizes.
             For example, ffoorrmmaatt==""%%uucchhaarr%%iinntt%%ffllooaatt"" associates an
             unsigned character with the first using column, an int
             with the second column and a float with the third column.
             If the number of size specifications is less than the
             greatest column number, the size is implicitly taken to be
             similar to the last given variable size.

             Furthermore, similar to the uussiinngg specification, the for-
             mat can include discarded columns via the ** character and
             have implicit repetition via a numerical repeat-field.
             For example, ffoorrmmaatt==""%%**22iinntt%%33ffllooaatt"" causes gnuplot to dis-
             card two ints before reading three floats.  To list vari-
             able sizes, type sshhooww ddaattaaffiillee bbiinnaarryy ddaattaassiizzeess.  There
             are a group of names that are machine dependent along with
             their sizes in bytes for the particular compilation.
             There is also a group of names which attempt to be machine
             independent.



             6688..22..77..  EEnnddiiaann


             Often the endianess of binary data in the file does not
             agree with the endianess used by the platform on which
             gnuplot is running.  Several words can direct gnuplot how
             to arrange bytes.  For example eennddiiaann==lliittttllee means treat
             the binary file as having byte significance from least to
             greatest. The options are

                           little:  least significant to greatest










   GNUPLOT 4.1                                                       86


             significance
                              big:  greatest significance to least sig-
             nificance
                          default:  assume file endianess is the same
             as compiler
                      swap (swab):  Interchange the significance.  (If
             things
                                    don't look right, try this.)

             Gnuplot can support "middle" ("pdp") endian if it is com-
             piled with that option.



             6688..22..88..  FFiilleettyyppee


             For some standard binary file formats gnuplot can extract
             all the necessary information from the file in question.
             As an example, "format=edf" will read ESRF Header File
             format files.  For a list of the currently supported file
             formats, type sshhooww ddaattaaffiillee bbiinnaarryy ffiilleettyyppeess.

             There is a special file type called aauuttoo for which gnuplot
             will check if the binary file's extension is a quasi-stan-
             dard extension for a supported format.

             Command line keywords may be used to override settings
             extracted from the file.  The settings from the file over-
             ride any defaults.  (See sseett ddaattaaffiillee bbiinnaarryy for details.)




                  6688..22..88..11..  AAvvss


                  aavvss is one of the automatically recognized binary
                  file types for images.  AVS is an extremely simple
                  format, suitable mostly for streaming between appli-
                  cations. It consists of 2 longs (xwidth, ywidth) fol-
                  lowed by a stream of pixels, each with four bytes of
                  information alpha/red/green/blue.



                  6688..22..88..22..  EEddff


                  eeddff is one of the automatically recognized binary
                  file types for images.  EDF stands for ESRF Data For-
                  mat, and it supports both edf and ehf formats (the
                  latter means ESRF Header Format).  More information










   GNUPLOT 4.1                                                       87


                  on specifications can be found at

                    http://www.edfplus.info/specs

                  See also bbiinnaarryy.



                  6688..22..88..33..  PPnngg


                  If gnuplot was configured to use the libgd library
                  for png/gif/jpeg output, then it can also be used to
                  read these same image types as binary files.  You can
                  use an explicit command
                        plot 'file.png' binary filetype=png
                  Or the file type will be recognized automatically
                  from the extension if you have previously requested
                        set datafile binary filetype=auto

                  See also bbiinnaarryy.



             6688..22..99..  KKeeyywwoorrddss


             The following keywords apply only when generating coordi-
             nates from binary data files.  That is, the control map-
             ping the individual elements of a binary array, matrix, or
             image to specific x/y/z positions.




                  6688..22..99..11..  SSccaann


                  A great deal of confusion can arise concerning the
                  relationship between how gnuplot scans a binary file
                  and the dimensions seen on the plot.  To lessen the
                  confusion, conceptually think of gnuplot _always_
                  scanning the binary file point/line/plane or
                  fast/medium/slow.  Then this keyword is used to tell
                  gnuplot how to map this scanning convention to the
                  Cartesian convention shown in plots, i.e., x/y/z.
                  The qualifier for scan is a two or three letter code
                  representing where point is assigned (first letter),
                  line is assigned (second letter), and plane is
                  assigned (third letter).  For example, ssccaann==yyxx means
                  the fastest, point-by-point, increment should be
                  mapped along the Cartesian y dimension and the mid-
                  dle, line-by-line, increment should be mapped along










   GNUPLOT 4.1                                                       88


                  the x dimension.

                  When the plotting mode is pplloott, the qualifier code
                  can include the two letters x and y.  For sspplloott, it
                  can include the three letters x, y and z.

                  There is nothing restricting the inherent mapping
                  from point/line/plane to apply only to Cartesian
                  coordinates.  For this reason there are cylindrical
                  coordinate synonyms for the qualifier codes where t
                  (theta), r and z are analogous to the x, y and z of
                  Cartesian coordinates.



                  6688..22..99..22..  TTrraannssppoossee


                  Shorthand notation for ssccaann==yyxx or ssccaann==yyxxzz.



                  6688..22..99..33..  DDxx,, ddyy,, ddzz


                  When gnuplot generates coordinates, it uses the spac-
                  ing described by these keywords.  For example ddxx==1100
                  ddyy==2200 would mean space samples along the x dimension
                  by 10 and space samples along the y dimension by 20.
                  ddyy cannot appear if ddxx does not appear.  Similarly,
                  ddzz cannot appear if ddyy does not appear.  If the
                  underlying dimensions are greater than the keywords
                  specified, the spacing of the highest dimension given
                  is extended to the other dimensions.  For example, if
                  an image is being read from a file and only ddxx==33..55 is
                  given gnuplot uses a delta x and delta y of 3.5.

                  The following keywords also apply only when generat-
                  ing coordinates.  However they may also be used with
                  matrix binary files.



                  6688..22..99..44..  FFlliippxx,, fflliippyy,, fflliippzz


                  Sometimes the scanning directions in a binary
                  datafile are not consistent with that assumed by gnu-
                  plot.  These keywords can flip the scanning direction
                  along dimensions x, y, z.













   GNUPLOT 4.1                                                       89


                  6688..22..99..55..  OOrriiggiinn


                  When gnuplot generates coordinates based upon trans-
                  position and flip, it attempts to always position the
                  lower left point in the array at the origin, i.e.,
                  the data lies in the first quadrant of a Cartesian
                  system after transpose and flip.

                  To position the array somewhere else on the graph,
                  the oorriiggiinn keyword directs gnuplot to position the
                  lower left point of the array at a point specified by
                  a tuple.  The tuple should be a double for pplloott and a
                  triple for sspplloott.  For example, oorrii--
                  ggiinn==((110000,,110000))::((110000,,220000)) is for two records in the
                  file and intended for plotting in two dimensions. A
                  second example, oorriiggiinn==((00,,00,,33..55)), is for plotting in
                  three dimensions.



                  6688..22..99..66..  CCeenntteerr


                  Similar to oorriiggiinn, this keyword will position the
                  array such that its center lies at the point given by
                  the tuple.  For example, cceenntteerr==((00,,00)).  Center does
                  not apply when the size of the array is IInnff.



                  6688..22..99..77..  RRoottaattee


                  The transpose and flip commands provide some flexi-
                  bility in generating and orienting coordinates.  How-
                  ever, for full degrees of freedom, it is possible to
                  apply a rotational vector described by a rotational
                  angle in two dimensions.

                  The rroottaattee keyword applies to the two-dimensional
                  plane, whether it be pplloott or sspplloott.  The rotation is
                  done with respect to the positive angle of the Carte-
                  sian plane.

                  The angle can be expressed in radians, radians as a
                  multiple of pi, or degrees.  For example,
                  rroottaattee==11..55770088, rroottaattee==00..55ppii and rroottaattee==9900ddeegg are
                  equivalent.

                  If oorriiggiinn is specified, the rotation is done about
                  the lower left sample point before translation.  Oth-
                  erwise, the rotation is done about the array cceenntteerr.










   GNUPLOT 4.1                                                       90


                  6688..22..99..88..  PPeerrppeennddiiccuullaarr


                  For sspplloott, the concept of a rotational vector is
                  implemented by a triple representing the vector to be
                  oriented normal to the two-dimensional x-y plane.
                  Naturally, the default is (0,0,1).  Thus specifying
                  both rotate and perpendicular together can orient
                  data myriad ways in three-space.

                  The two-dimensional rotation is done first, followed
                  by the three-dimensional rotation.  That is, if R' is
                  the rotational 2 x 2 matrix described by an angle,
                  and P is the 3 x 3 matrix projecting (0,0,1) to
                  (xp,yp,zp), let R be constructed from R' at the upper
                  left sub-matrix, 1 at element 3,3 and zeros else-
                  where.  Then the matrix formula for translating data
                  is v' = P R v, where v is the 3 x 1 vector of data
                  extracted from the data file.  In cases where the
                  data of the file is inherently not three-dimensional,
                  logical rules are used to place the data in three-
                  space.  (E.g., usually setting the z-dimension value
                  to zero and placing 2D data in the x-y plane.)



                  6688..22..99..99..  BBiinnaarryy eexxaammpplleess


                  Examples:

                        # Selects two float values (second one
                  implicit) with a float value
                        # discarded between them for an indefinite
                  length of 1D data.
                        plot '<file_name>' binary for-
                  mat="%float%*float" using 1:2 with lines

                        # The data file header contains all details
                  necessary for creating
                        # coordinates from an EDF file.
                        plot '<file_name>' binary filetype=edf with
                  image
                        plot '<file_name>.edf' binary filetype=auto
                  with image

                        # Selects three unsigned characters for compo-
                  nents of a raw RGB image
                        # and flips the y-dimension so that typical
                  image orientation (start
                        # at top left corner) translates to the Carte-
                  sian plane.  Pixel
                        # spacing is given and there are two images in










   GNUPLOT 4.1                                                       91


                  the file.  One of them
                        # is translated via origin.
                        plot '<file_name>' binary
                  array=(512,1024):(1024,512) format='%uchar' \
                             dx=2:1 dy=1:2 origin=(0,0):(1024,1024)
                  flipy u 1:2:3 w rgbimage

                        # Four separate records in which the coordi-
                  nates are part of the
                        # data file.  The file was created with a endi-
                  aness different from
                        # the system on which gnuplot is running.
                        splot '<file_name>' binary record=30:30:29:26
                  endian=swap u 1:2:3

                        # Same input file, but this time we skip the
                  1st and 3rd records
                        splot '<file_name>' binary record=30:26
                  skip=360:348 endian=swap u 1:2:3


                  See also bbiinnaarryy mmaattrriixx.



             6688..22..1100..  EEvveerryy


             The eevveerryy keyword allows a periodic sampling of a data set
             to be plotted.

             In the discussion a "point" is a datum defined by a single
             record in the file; "block" here will mean the same thing
             as "datablock" (see gglloossssaarryy).

             Syntax:
                   plot 'file' every {<point_incr>}
                                       {:{<block_incr>}
                                         {:{<start_point>}
                                           {:{<start_block>}
                                             {:{<end_point>}
                                               {:<end_block>}}}}}

             The data points to be plotted are selected according to a
             loop from <ssttaarrtt__ppooiinntt> to <eenndd__ppooiinntt> with increment
             <ppooiinntt__iinnccrr> and the blocks according to a loop from
             <ssttaarrtt__bblloocckk> to <eenndd__bblloocckk> with increment <bblloocckk__iinnccrr>.

             The first datum in each block is numbered '0', as is the
             first block in the file.

             Note that records containing unplottable information are
             counted.










   GNUPLOT 4.1                                                       92


             Any of the numbers can be omitted; the increments default
             to unity, the start values to the first point or block,
             and the end values to the last point or block.  If eevveerryy
             is not specified, all points in all lines are plotted.

             Examples:
                   every :::3::3    # selects just the fourth block
             ('0' is first)
                   every :::::9     # selects the first 10 blocks
                   every 2:2        # selects every other point in
             every other block
                   every ::5::15    # selects points 5 through 15 in
             each block

             See simple plot demos (simple.dem) , Non-parametric splot
             demos , and Parametric splot demos .



             6688..22..1111..  EExxaammppllee ddaattaaffiillee


             This example plots the data in the file "population.dat"
             and a theoretical curve:

                   pop(x) = 103*exp((1965-x)/10)
                   plot [1960:1990] 'population.dat', pop(x)

             The file "population.dat" might contain:

                   # Gnu population in Antarctica since 1965
                      1965   103
                      1970   55
                      1975   34
                      1980   24
                      1985   10




             6688..22..1122..  IInnddeexx


             The iinnddeexx keyword allows you to select specific data sets
             in a multi-data-set file for plotting.

             Syntax:
                   plot 'file' index { <m>{:<n>{:<p>}} | "<name>" }

             Data sets are separated by pairs of blank records.  iinnddeexx
             <<mm>> selects only set <m>; iinnddeexx <<mm>>::<<nn>> selects sets in
             the range <m> to <n>; and iinnddeexx <<mm>>::<<nn>>::<<pp>> selects
             indices <m>, <m>+<p>, <m>+2<p>, etc., but stopping at <n>.










   GNUPLOT 4.1                                                       93


             Following C indexing, the index 0 is assigned to the first
             data set in the file.  Specifying too large an index
             results in an error message.  If <p> is specified but <n>
             is left blank then every <p>-th dataset is read until the
             end of the file.  If iinnddeexx is not specified, the entire
             file is plotted as a single data set.

             Example:
                   plot 'file' index 4:5

             For each point in the file, the index value of the data
             set it appears in is available via the pseudo-column ccooll--
             uummnn((--22)).  This leads to an alternative way of distinguish-
             ing individual data sets within a file as shown below.
             This is more awkward than the iinnddeexx command if all you are
             doing is selecting one data set for plotting, but is very
             useful if you want to assign different properties to each
             data set.  See ppsseeuuddooccoolluummnnss, llcc vvaarriiaabbllee.

             Example:
                   plot 'file' using 1:(column(-2)==4 ? $2 : NaN)
             # very awkward
                   plot 'file' using 1:2:(column(-2)) linecolor vari-
             able # very useful!

             iinnddeexx ''<<nnaammee>>'' selects the data set with name '<name>'.
             Names are assigned to data sets in comment lines.  The
             comment character and leading white space are removed from
             the comment line.  If the resulting line starts with
             <name>, the following data set is now named <name> and can
             be selected.

             Example:
                   plot 'file' index 'Population'

             Please note that every comment that starts with <name>
             will name the following data set.  To avoid problems it
             may be useful to choose a naming scheme like '== Popula-
             tion ==' or '[Population]'.




             6688..22..1133..  SSmmooootthh


             ggnnuupplloott includes a few general-purpose routines for inter-
             polation and approximation of data; these are grouped
             under the ssmmooootthh option.  More sophisticated data process-
             ing may be performed by preprocessing the data externally
             or by using ffiitt with an appropriate model.

             Syntax:










   GNUPLOT 4.1                                                       94


                   smooth {unique | frequency | cumulative | kdensity |
             csplines | acsplines | bezier | sbezier}

             uunniiqquuee, ffrreeqquueennccyy, and ccuummuullaattiivvee plot the data after mak-
             ing them monotonic.  Each of the other routines uses the
             data to determine the coefficients of a continuous curve
             between the endpoints of the data.  This curve is then
             plotted in the same manner as a function, that is, by
             finding its value at uniform intervals along the abscissa
             (see sseett ssaammpplleess) and connecting these points with
             straight line segments (if a line style is chosen).

             If aauuttoossccaallee is in effect, the ranges will be computed
             such that the plotted curve lies within the borders of the
             graph.

             If aauuttoossccaallee is not in effect, and the smooth option is
             either aaccsspplliinnee or ccsspplliinnee, the sampling of the generated
             curve is done across the intersection of the x range cov-
             ered by the input data and the fixed abscissa range as
             defined by sseett xxrraannggee.

             If too few points are available to allow the selected
             option to be applied, an error message is produced.  The
             minimum number is one for uunniiqquuee and ffrreeqquueennccyy, four for
             aaccsspplliinneess, and three for the others.

             The ssmmooootthh options have no effect on function plots.




                  6688..22..1133..11..  AAccsspplliinneess


                  The aaccsspplliinneess option approximates the data with a
                  "natural smoothing spline".  After the data are made
                  monotonic in x (see ssmmooootthh uunniiqquuee), a curve is piece-
                  wise constructed from segments of cubic polynomials
                  whose coefficients are found by the weighting the
                  data points; the weights are taken from the third
                  column in the data file.  That default can be modi-
                  fied by the third entry in the uussiinngg list, e.g.,
                        plot 'data-file' using 1:2:(1.0) smooth
                  acsplines

                  Qualitatively, the absolute magnitude of the weights
                  determines the number of segments used to construct
                  the curve.  If the weights are large, the effect of
                  each datum is large and the curve approaches that
                  produced by connecting consecutive points with natu-
                  ral cubic splines.  If the weights are small, the
                  curve is composed of fewer segments and thus is










   GNUPLOT 4.1                                                       95


                  smoother; the limiting case is the single segment
                  produced by a weighted linear least squares fit to
                  all the data.  The smoothing weight can be expressed
                  in terms of errors as a statistical weight for a
                  point divided by a "smoothing factor" for the curve
                  so that (standard) errors in the file can be used as
                  smoothing weights.

                  Example:
                        sw(x,S)=1/(x*x*S)
                        plot 'data_file' using 1:2:(sw($3,100)) smooth
                  acsplines



                  6688..22..1133..22..  BBeezziieerr


                  The bbeezziieerr option approximates the data with a Bezier
                  curve of degree n (the number of data points) that
                  connects the endpoints.



                  6688..22..1133..33..  CCsspplliinneess


                  The ccsspplliinneess option connects consecutive points by
                  natural cubic splines after rendering the data mono-
                  tonic (see ssmmooootthh uunniiqquuee).



                  6688..22..1133..44..  SSbbeezziieerr


                  The ssbbeezziieerr option first renders the data monotonic
                  (uunniiqquuee) and then applies the bbeezziieerr algorithm.



                  6688..22..1133..55..  UUnniiqquuee


                  The uunniiqquuee option makes the data monotonic in x;
                  points with the same x-value are replaced by a single
                  point having the average y-value.  The resulting
                  points are then connected by straight line segments.















   GNUPLOT 4.1                                                       96


                  6688..22..1133..66..  FFrreeqquueennccyy


                  The ffrreeqquueennccyy option makes the data monotonic in x;
                  points with the same x-value are replaced by a single
                  point having the summed y-values.  The resulting
                  points are then connected by straight line segments.
                  See also smooth.dem



                  6688..22..1133..77..  CCuummuullaattiivvee


                  The ccuummuullaattiivvee option makes the data monotonic in x;
                  points with the same x-value are replaced by a single
                  point containing the cumulative sum of y-values of
                  all data points with lower x-values (i.e. to the left
                  of the current data point). This can be used to
                  obtain a cumulative distribution function from data.
                  See also smooth.dem



                  6688..22..1133..88..  KKddeennssiittyy


                  The kkddeennssiittyy option is a way to plot a kernel density
                  estimate (which is a smooth histogram) for a random
                  collection of points, using Gaussian kernels.  A
                  Gaussian is placed at the location of each point in
                  the first column and the sum of all these Gaussians
                  is plotted as a function. The value in the second
                  column is taken as weight of the Gaussian. (To obtain
                  a normalized histogram, this should be 1/number-of-
                  points). The value of the third column, if supplied,
                  is taken as the bandwidth for the kernels. If only
                  two columns have been specified, or if the value of
                  the third column is zero or less, gnuplot calculates
                  the bandwidth which would be optimal if the input
                  data was normally distributed. (This will usually be
                  a very conservative, i.e. broad bandwidth.)



             6688..22..1144..  SSppeecciiaall--ffiilleennaammeess


             There are a few filenames that have a special meaning:
             '', '-', '+' and '++'.

             The empty filename '' tells gnuplot to re-use the previous
             input file in the same plot command. So to plot two










   GNUPLOT 4.1                                                       97


             columns from the same input file:

                   plot 'filename' using 1:2, '' using 1:3

             The special filenames '+' and '++' are a mechanism to
             allow the full range of uussiinngg specifiers and plot styles
             with in-line functions.  Normally a function plot can only
             have a single y (or z) value associated with each sampled
             point.  The pseudo-file '+' treats the sampled points as
             column 1, and allows additional column values to be speci-
             fied via a uussiinngg specification, just as for a true input
             file.  The number of samples returned is controlled by sseett
             ssaammpplleess.  Example:

                   plot '+' using ($1):(sin($1)):(sin($1)**2) with
             filledcurves

             Similarly the pseudo-file '++' returns 2 columns of data
             forming a regular grid of [x,y] coordinates with the num-
             ber of points along x controlled by sseett ssaammpplleess and the
             number of points along y controlled by sseett iissoossaammpplleess.
             You must set xrange and yrange before plotting '++'.
             Examples:

                   splot '++' using 1:2:(sin($1)*sin($2)) with pm3d
                   plot '++' using 1:2:(sin($1)*sin($2)) with image

             The special filename ''--'' specifies that the data are
             inline; i.e., they follow the command.  Only the data fol-
             low the command; pplloott options like filters, titles, and
             line styles remain on the pplloott command line.  This is sim-
             ilar to << in unix shell script, and $DECK in VMS DCL.
             The data are entered as though they are being read from a
             file, one data point per record.  The letter "e" at the
             start of the first column terminates data entry.  The
             uussiinngg option can be applied to these data---using it to
             filter them through a function might make sense, but
             selecting columns probably doesn't!

             ''--'' is intended for situations where it is useful to have
             data and commands together, e.g., when ggnnuupplloott is run as a
             sub-process of some front-end application.  Some of the
             demos, for example, might use this feature.  While pplloott
             options such as iinnddeexx and eevveerryy are recognized, their use
             forces you to enter data that won't be used.  For example,
             while

                   plot '-' index 0, '-' index 1
                   2
                   4
                   6












   GNUPLOT 4.1                                                       98


                   10
                   12
                   14
                   e
                   2
                   4
                   6


                   10
                   12
                   14
                   e

             does indeed work,

                   plot '-', '-'
                   2
                   4
                   6
                   e
                   10
                   12
                   14
                   e

             is a lot easier to type.

             If you use ''--'' with rreepplloott, you may need to enter the data
             more than once.  See rreepplloott, rreeffrreesshh.

             A blank filename ('') specifies that the previous filename
             should be reused.  This can be useful with things like

                   plot 'a/very/long/filename' using 1:2, '' using 1:3,
             '' using 1:4

             (If you use both ''--'' and '''' on the same pplloott command,
             you'll need to have two sets of inline data, as in the
             example above.)

             On systems with a popen function, the datafile can be
             piped through a shell command by starting the file name
             with a '<'.  For example,

                   pop(x) = 103*exp(-x/10)
                   plot "< awk '{print $1-1965, $2}' population.dat",
             pop(x)

             would plot the same information as the first population
             example but with years since 1965 as the x axis.  If you
             want to execute this example, you have to delete all com-
             ments from the data file above or substitute the following










   GNUPLOT 4.1                                                       99


             command for the first part of the command above (the part
             up to the comma):

                   plot "< awk '$0 !~ /^#/ {print $1-1965, $2}' popula-
             tion.dat"

             While this approach is most flexible, it is possible to
             achieve simple filtering with the uussiinngg or tthhrruu keywords.



             6688..22..1155..  TThhrruu


             The tthhrruu function is provided for backward compatibility.

             Syntax:
                   plot 'file' thru f(x)

             It is equivalent to:

                   plot 'file' using 1:(f($2))

             While the latter appears more complex, it is much more
             flexible.  The more natural

                   plot 'file' thru f(y)

             also works (i.e. you can use y as the dummy variable).

             tthhrruu is parsed for sspplloott and ffiitt but has no effect.



             6688..22..1166..  UUssiinngg


             The most common datafile modifier is uussiinngg.

             Syntax:
                   plot 'file' using {<entry> {:<entry> {:<entry>
             ...}}} {'format'}

             If a format is specified, each datafile record is read
             using the C library's 'scanf' function, with the specified
             format string.  Otherwise the record is read and broken
             into columns. By default the separation between columns is
             whitespace (spaces and/or tabs), but see ddaattaaffiillee sseeppaarraa--
             ttoorr.

             Each <entry> may be a simple column number that selects
             the value from one field of the input fit, an expression
             enclosed in parentheses, or empty.










   GNUPLOT 4.1                                                      100


             If the entry is an expression in parentheses, then the
             function column(N) may be used to indicate the value in
             column N. That is, column(1) refers to the first item
             read, column(2) to the second, and so on.  The special
             symbols $1, $2, ... are shorthand for column(1), column(2)
             ...  The function vvaalliidd((NN)) tests whether the value in the
             Nth column is a valid number.

             In addition to the actual columns 1...N in the input data
             file, gnuplot presents data from several "pseudo-columns"
             that hold bookkeeping information.  E.g. $0 or column(0)
             returns the sequence number of this data record within a
             dataset.  Please see ppsseeuuddooccoolluummnnss.

             An empty <entry> will default to its order in the list of
             entries.  For example, uussiinngg ::::44 is interpreted as uussiinngg
             11::22::44.

             If the uussiinngg list has but a single entry, that <entry>
             will be used for y and the data point number (pseudo-col-
             umn $0) is used for x; for example, "pplloott ''ffiillee'' uussiinngg 11"
             is identical to "pplloott ''ffiillee'' uussiinngg 00::11".  If the uussiinngg
             list has two entries, these will be used for x and y.  See
             sseett ssttyyllee and ffiitt for details about plotting styles that
             make use of data from additional columns of input.

             'scanf' accepts several numerical specifications but ggnnuu--
             pplloott requires all inputs to be double-precision floating-
             point variables, so "%lf" is essentially the only permis-
             sible specifier.  A format string given by the user must
             contain at least one such input specifier, and no more
             than seven of them.  'scanf' expects to see white
             space---a blank, tab ("\t"), newline ("\n"), or formfeed
             ("\f")---between numbers; anything else in the input
             stream must be explicitly skipped.

             Note that the use of "\t", "\n", or "\f" requires use of
             double-quotes rather than single-quotes.




                  6688..22..1166..11..  UUssiinngg__eexxaammpplleess


                  This creates a plot of the sum of the 2nd and 3rd
                  data against the first: The format string specifies
                  comma- rather than space-separated columns.  The same
                  result could be achieved by specifying sseett ddaattaaffiillee
                  sseeppaarraattoorr "",,"".
                        plot 'file' using 1:($2+$3) '%lf,%lf,%lf'

                  In this example the data are read from the file










   GNUPLOT 4.1                                                      101


                  "MyData" using a more complicated format:
                        plot 'MyData' using "%*lf%lf%*20[^\n]%lf"

                  The meaning of this format is:

                        %*lf        ignore a number
                        %lf         read a double-precision number (x
                  by default)
                        %*20[^\n]   ignore 20 non-newline characters
                        %lf         read a double-precision number (y
                  by default)

                  One trick is to use the ternary ??:: operator to filter
                  data:

                        plot 'file' using 1:($3>10 ? $2 : 1/0)

                  which plots the datum in column two against that in
                  column one provided the datum in column three exceeds
                  ten.  11//00 is undefined; ggnnuupplloott quietly ignores unde-
                  fined points, so unsuitable points are suppressed.
                  Or you can use the pre-defined variable NaN to
                  achieve the same result.

                  In fact, you can use a constant expression for the
                  column number, provided it doesn't start with an
                  opening parenthesis; constructs like uussiinngg 00++((ccoommppllii--
                  ccaatteedd eexxpprreessssiioonn)) can be used.  The crucial point is
                  that the expression is evaluated once if it doesn't
                  start with a left parenthesis, or once for each data
                  point read if it does.

                  If timeseries data are being used, the time can span
                  multiple columns.  The starting column should be
                  specified.  Note that the spaces within the time must
                  be included when calculating starting columns for
                  other data.  E.g., if the first element on a line is
                  a time with an embedded space, the y value should be
                  specified as column three.

                  It should be noted that pplloott ''ffiillee'', pplloott ''ffiillee''
                  uussiinngg 11::22, and pplloott ''ffiillee'' uussiinngg (($$11))::(($$22)) can be
                  subtly different: 1) if ffiillee has some lines with one
                  column and some with two, the first will invent x
                  values when they are missing, the second will quietly
                  ignore the lines with one column, and the third will
                  store an undefined value for lines with one point (so
                  that in a plot with lines, no line joins points
                  across the bad point); 2) if a line contains text at
                  the first column, the first will abort the plot on an
                  error, but the second and third should quietly skip
                  the garbage.











   GNUPLOT 4.1                                                      102


                  In fact, it is often possible to plot a file with
                  lots of lines of garbage at the top simply by speci-
                  fying

                        plot 'file' using 1:2

                  However, if you want to leave text in your data
                  files, it is safer to put the comment character (#)
                  in the first column of the text lines.  Feeble using
                  demos.



                  6688..22..1166..22..  PPsseeuuddooccoolluummnnss


                  Expressions in the uussiinngg clause of a plot statement
                  can refer to additional bookkeeping values in addi-
                  tion to the actual data values contained in the input
                  file. These are contained in "pseudocolumns".
                        column(0)   The sequential order of each point
                  within a data set.
                                    The counter starts at 0 and is
                  reset by two sequential blank
                                    records.  The shorthand form $0 is
                  available.
                        column(-1)  This counter starts at 0 and is
                  reset by a single blank line.
                                    This corresponds to the data line
                  in array or grid data.
                        column(-2)  The index number of the current
                  data set within a file that
                                    contains multiple data sets.  See
                  `index`.



                  6688..22..1166..33..  XXttiiccllaabbeellss


                  Axis tick labels can be generated via a string func-
                  tion, usually taking a data column as an argument.
                  The simplest form uses the data column itself as a
                  string. That is,  xticlabels(N) is shorthand for xti-
                  clabels(stringcolumn(N)).  This example uses the con-
                  tents of column 3 as x-axis tick labels.

                        plot 'datafile' using <xcol>:<ycol>:xticla-
                  bels(3) with <plotstyle>

                  Axis tick labels may be generated for any of the plot
                  axes: x x2 y y2 z.  The ttiiccllaabbeellss((<<llaabbeellccooll>>)) speci-
                  fiers must come after all of the data coordinate










   GNUPLOT 4.1                                                      103


                  specifiers in the uussiinngg portion of the command.  For
                  each data point which has a valid set of X,Y[,Z]
                  coordinates, the string value given to xticlabels()
                  is added to the list of xtic labels at the same X
                  coordinate as the point it belongs to. xxttiiccllaabbeellss(())
                  may be shortened to xxttiicc(()) and so on.

                  Example:

                        splot "data" using
                  2:4:6:xtic(1):ytic(3):ztic(6)

                  In this example the x and y axis tic labels are taken
                  from different columns than the x and y coordinate
                  values. The z axis tics, however, are generated from
                  the z coordinate of the corresponding point.

                  Example:

                        plot "data" using 1:2:xtic( $3 > 10. ? "A" :
                  "B" )

                  This example shows the use of a string-valued func-
                  tion to generate x-axis tick labels. Each point in
                  the data file generates a tick mark on x labeled
                  either "A" or "B" depending on the value in column 3.



                  6688..22..1166..44..  XX22ttiiccllaabbeellss


                  See pplloott uussiinngg xxttiiccllaabbeellss.



                  6688..22..1166..55..  YYttiiccllaabbeellss


                  See pplloott uussiinngg xxttiiccllaabbeellss.



                  6688..22..1166..66..  YY22ttiiccllaabbeellss


                  See pplloott uussiinngg xxttiiccllaabbeellss.
















   GNUPLOT 4.1                                                      104


                  6688..22..1166..77..  ZZttiiccllaabbeellss


                  See pplloott uussiinngg xxttiiccllaabbeellss.



        6688..33..  EErrrroorrbbaarrss


        Error bars are supported for 2D data file plots by reading one
        to four additional columns (or uussiinngg entries); these additional
        values are used in different ways by the various errorbar
        styles.

        In the default situation, ggnnuupplloott expects to see three, four,
        or six numbers on each line of the data file---either

              (x, y, ydelta),
              (x, y, ylow, yhigh),
              (x, y, xdelta),
              (x, y, xlow, xhigh),
              (x, y, xdelta, ydelta), or
              (x, y, xlow, xhigh, ylow, yhigh).

        The x coordinate must be specified.  The order of the numbers
        must be exactly as given above, though the uussiinngg qualifier can
        manipulate the order and provide values for missing columns.
        For example,

              plot 'file' with errorbars
              plot 'file' using 1:2:(sqrt($1)) with xerrorbars
              plot 'file' using 1:2:($1-$3):($1+$3):4:5 with xyerror-
        bars

        The last example is for a file containing an unsupported combi-
        nation of relative x and absolute y errors.  The uussiinngg entry
        generates absolute x min and max from the relative error.

        The y error bar is a vertical line plotted from (x, ylow) to
        (x, yhigh). If ydelta is specified instead of ylow and yhigh,
        ylow = y - ydelta and yhigh = y + ydelta are derived. If there
        are only two numbers on the record, yhigh and ylow are both set
        to y. The x error bar is a horizontal line computed in the same
        fashion. To get lines plotted between the data points, pplloott the
        data file twice, once with errorbars and once with lines (but
        remember to use the nnoottiittllee option on one to avoid two entries
        in the key). Alternately, use the errorlines command (see
        eerrrroorrlliinneess).

        The error bars have crossbars at each end unless sseett bbaarrss is
        used (see sseett bbaarrss for details).











   GNUPLOT 4.1                                                      105


        If autoscaling is on, the ranges will be adjusted to include
        the error bars.

        See also errorbar demos.

        See pplloott uussiinngg, pplloott wwiitthh, and sseett ssttyyllee for more information.



        6688..44..  EErrrroorrlliinneess


        Lines with error bars are supported for 2D data file plots by
        reading one to four additional columns (or uussiinngg entries);
        these additional values are used in different ways by the vari-
        ous errorlines styles.

        In the default situation, ggnnuupplloott expects to see three, four,
        or six numbers on each line of the data file---either

              (x, y, ydelta),
              (x, y, ylow, yhigh),
              (x, y, xdelta),
              (x, y, xlow, xhigh),
              (x, y, xdelta, ydelta), or
              (x, y, xlow, xhigh, ylow, yhigh).

        The x coordinate must be specified. The order of the numbers
        must be exactly as given above, though the uussiinngg qualifier can
        manipulate the order and provide values for missing columns.
        For example,

              plot 'file' with errorlines
              plot 'file' using 1:2:(sqrt($1)) with xerrorlines
              plot 'file' using 1:2:($1-$3):($1+$3):4:5 with xyerror-
        lines

        The last example is for a file containing an unsupported combi-
        nation of relative x and absolute y errors. The uussiinngg entry
        generates absolute x min and max from the relative error.

        The y error bar is a vertical line plotted from (x, ylow) to
        (x, yhigh). If ydelta is specified instead of ylow and yhigh,
        ylow = y - ydelta and yhigh = y + ydelta are derived. If there
        are only two numbers on the record, yhigh and ylow are both set
        to y. The x error bar is a horizontal line computed in the same
        fashion.

        The error bars have crossbars at each end unless sseett bbaarrss is
        used (see sseett bbaarrss for details).

        If autoscaling is on, the ranges will be adjusted to include
        the error bars.










   GNUPLOT 4.1                                                      106


        See pplloott uussiinngg, pplloott wwiitthh, and sseett ssttyyllee for more information.



        6688..55..  PPaarraammeettrriicc


        When in parametric mode (sseett ppaarraammeettrriicc) mathematical expres-
        sions must be given in pairs for pplloott and in triplets for
        sspplloott.

        Examples:
              plot sin(t),t**2
              splot cos(u)*cos(v),cos(u)*sin(v),sin(u)

        Data files are plotted as before, except any preceding paramet-
        ric function must be fully specified before a data file is
        given as a plot.  In other words, the x parametric function
        (ssiinn((tt)) above) and the y parametric function (tt****22 above) must
        not be interrupted with any modifiers or data functions; doing
        so will generate a syntax error stating that the parametric
        function is not fully specified.

        Other modifiers, such as wwiitthh and ttiittllee, may be specified only
        after the parametric function has been completed:

              plot sin(t),t**2 title 'Parametric example' with lines-
        points

        See also Parametric Mode Demos.



        6688..66..  RRaannggeess


        The optional ranges specify the region of the graph that will
        be displayed.

        Syntax:
              [{<dummy-var>=}{{<min>}:{<max>}}]
              [{{<min>}:{<max>}}]

        The first form applies to the independent variable (xxrraannggee or
        ttrraannggee, if in parametric mode).  The second form applies to the
        dependent variable yyrraannggee (and xxrraannggee, too, if in parametric
        mode).  <dummy-var> is a new name for the independent variable.
        (The defaults may be changed with sseett dduummmmyy.)  The optional
        <min> and <max> terms can be constant expressions or *.

        In non-parametric mode, the order in which ranges must be given
        is xxrraannggee and yyrraannggee.











   GNUPLOT 4.1                                                      107


        In parametric mode, the order for the pplloott command is ttrraannggee,
        xxrraannggee, and yyrraannggee.  The following pplloott command shows setting
        the ttrraannggee to [-pi:pi], the xxrraannggee to [-1.3:1.3] and the yyrraannggee
        to [-1:1] for the duration of the graph:

              plot [-pi:pi] [-1.3:1.3] [-1:1] sin(t),t**2

        Note that the x2range and y2range cannot be specified
        here---sseett xx22rraannggee and sseett yy22rraannggee must be used.

        Ranges are interpreted in the order listed above for the appro-
        priate mode.  Once all those needed are specified, no further
        ones must be listed, but unneeded ones cannot be skipped---use
        an empty range [[]] as a placeholder.

        ** can be used to allow autoscaling of either of min and max.
        See also sseett aauuttoossccaallee.

        Ranges specified on the pplloott or sspplloott command line affect only
        that graph; use the sseett xxrraannggee, sseett yyrraannggee, etc., commands to
        change the default ranges for future graphs.

        With time data, you must provide the range (in the same manner
        as the time appears in the datafile) within quotes.  ggnnuupplloott
        uses the ttiimmeeffmmtt string to read the value---see sseett ttiimmeeffmmtt.

        Examples:

        This uses the current ranges:
              plot cos(x)

        This sets the x range only:
              plot [-10:30] sin(pi*x)/(pi*x)

        This is the same, but uses t as the dummy-variable:
              plot [t = -10 :30]  sin(pi*t)/(pi*t)

        This sets both the x and y ranges:
              plot [-pi:pi] [-3:3]  tan(x), 1/x

        This sets only the y range, and turns off autoscaling on both
        axes:
              plot [ ] [-2:sin(5)*-8] sin(x)**besj0(x)

        This sets xmax and ymin only:
              plot [:200] [-pi:]  exp(sin(x))

        This sets the x range for a timeseries:
              set timefmt "%d/%m/%y %H:%M"
              plot ["1/6/93 12:00":"5/6/93 12:00"] 'timedata.dat'













   GNUPLOT 4.1                                                      108


        6688..77..  IItteerraattiioonn


        If many similar files or functions are to be plotted together,
        it may be convenient to do so by iterating over a shared plot
        command.

        Syntax:
              plot for [<variable> = <start> : <end> {:<increment>}]
              plot for [<variable> in "string of words"]

        The scope of an iteration ends at the next comma or the end of
        the command, whichever comes first.  Iteration can not be
        nested.

        This will plot one curve, sin(3x), because iteration ends at
        the comma
              plot for [i=1:3] j=i, sin(j*x)
        This will plot three curves because there is no comma after the
        definition of j
              plot for [i=1:3] j=i sin(j*x)

        Example:
              plot for [dataset in "apples bananas"] dataset."dat"
        title dataset

        In this example iteration is used both to generate a file name
        and a corresponding title.

        Example:
              file(n) = sprintf("dataset_%d.dat",n)
              splot for [i=1:10] file(i) title sprintf("dataset %d",i)

        This example defines a string-valued function that generates
        file names, and plots ten such files together. The iteration
        variable ('i' in this example) is treated as an integer, and
        may be used more than once.

        Example:
              set key left
              plot [0:1] for [n=1:4] x**n sprintf("%d",n)

        This example plots a family of functions.

        Example:
              list = "apple banana cabbage daikon eggplant"
              item(n) = word(list,n)
              plot for [i=1:words(list)] item[i].".dat" title item(i)
              list = "new stuff"
              replot

        This example steps through a list and plots once per item.
        Because the items are retrieved dynamically, you can change the










   GNUPLOT 4.1                                                      109


        list and then replot.

        Example:
              list = "apple banana cabbage daikon eggplant"
              plot for [i in list] i.".dat" title i
              list = "new stuff"
              replot

        This is example does exactly the same thing as the previous
        example, but uses the string iterator form of the command
        rather than an integer iterator.




        6688..88..  TTiittllee


        By default each plot is listed in the key by the corresponding
        function or file name. You can give an explicit plot title
        instead using the ttiittllee option.

        Syntax:
              title <text> | notitle [<ignored text>]
              title columnheader | title columnheader(N)

        where <text> is a quoted string or an expression that evaluates
        to a string.  The quotes will not be shown in the key.

        There is also an option that will interpret the first entry in
        a column of input data (i.e. the column header) as a text
        field, and use it as the key title.  See ddaattaassttrriinnggss.  This can
        be made the default by specifying sseett kkeeyy aauuttoottiittllee ccoolluummnnhheeaadd.

        The line title and sample can be omitted from the key by using
        the keyword nnoottiittllee.  A null title (ttiittllee '''') is equivalent to
        nnoottiittllee.  If only the sample is wanted, use one or more blanks
        (ttiittllee '' '').  If nnoottiittllee is followed by a string this string is
        ignored.

        If kkeeyy aauuttoottiittlleess is set (which is the default) and neither
        ttiittllee nor nnoottiittllee are specified the line title is the function
        name or the file name as it appears on the pplloott command.  If it
        is a file name, any datafile modifiers specified will be
        included in the default title.

        The layout of the key itself (position, title justification,
        etc.) can be controlled by sseett kkeeyy.  Please see sseett kkeeyy for
        details.

        Examples:

        This plots y=x with the title 'x':










   GNUPLOT 4.1                                                      110


              plot x

        This plots x squared with title "x^2" and file "data.1" with
        title "measured data":
              plot x**2 title "x^2", 'data.1' t "measured data"

        This puts an untitled circular border around a polar graph:
              set polar; plot my_function(t), 1 notitle

        Plot multiple columns of data, each of which contains its own
        title in the file
              plot for [i=1:4] 'data' using i title columnhead




        6688..99..  WWiitthh


        Functions and data may be displayed in one of a large number of
        styles.  The wwiitthh keyword provides the means of selection.

        Syntax:
              with <style> { {linestyle | ls <line_style>}
                             | {{linetype  | lt <line_type>}
                                {linewidth | lw <line_width>}
                                {linecolor | lc <colorspec>}
                                {pointtype | pt <point_type>}
                                {pointsize | ps <point_size>}
                                {fill | fs <fillstyle>}
                                {nohidden3d} {nocontours} {nosurface}
                                {palette}}
                           }


        where <style> is one of

             lines        dots       steps     errorbars     xerrorbar
        xyerrorlines
             points       impulses   fsteps    errorlines    xerror-
        lines  yerrorbars
             linespoints  labels     histeps   financebars   xyerror-
        bars  yerrorlines
                                               vectors
        or
              boxes            candlesticks   image      circles
              boxerrorbars     filledcurves   rgbimage
              boxxyerrorbars   histograms     rgbalpha   pm3d

        The first group of styles have associated line, point, and text
        properties.  The second group of styles also have fill proper-
        ties.  See ffiillllssttyyllee.  Some styles have further sub-styles.
        See pplloottttiinngg ssttyylleess for details of each.










   GNUPLOT 4.1                                                      111


        A default style may be chosen by sseett ssttyyllee ffuunnccttiioonn and sseett
        ssttyyllee ddaattaa.

        By default, each function and data file will use a different
        line type and point type, up to the maximum number of available
        types.  All terminal drivers support at least six different
        point types, and re-use them, in order, if more are required.
        To see the complete set of line and point types available for
        the current terminal, type tteesstt.

        If you wish to choose the line or point type for a single plot,
        <line_type> and <point_type> may be specified.  These are posi-
        tive integer constants (or expressions) that specify the line
        type and point type to be used for the plot.  Use tteesstt to dis-
        play the types available for your terminal.

        You may also scale the line width and point size for a plot by
        using <line_width> and <point_size>, which are specified rela-
        tive to the default values for each terminal.  The pointsize
        may also be altered globally---see sseett ppooiinnttssiizzee for details.
        But note that both <point_size> as set here and  as set by sseett
        ppooiinnttssiizzee multiply the default point size---their effects are
        not cumulative.  That is, sseett ppooiinnttssiizzee 22;; pplloott xx ww pp ppss 33 will
        use points three times default size, not six.

        It is also possible to specify ppooiinnttssiizzee vvaarriiaabbllee either as
        part of a line style or for an individual plot. In this case
        one extra column of input is required, i.e. 3 columns for a 2D
        plot and 4 columns for a 3D splot. The size of each individual
        point is determined by multiplying the global pointsize by the
        value read from the data file.

        If you have defined specific line type/width and point
        type/size combinations with sseett ssttyyllee lliinnee, one of these may be
        selected by setting <line_style> to the index of the desired
        style.

        If gnuplot was built with ppmm33dd support, the special keyword
        ppaalleettttee is allowed for smooth color change of lines, points and
        dots in sspplloottss. The color is chosen from a smooth palette which
        was set previously with the command sseett ppaalleettttee. The color
        value corresponds to the z-value of the point coordinates or to
        the color coordinate if specified by the 4th parameter in
        uussiinngg. Both 2d and 3d plots (pplloott and sspplloott commands) can use
        palette colors as specified by either their fractional value or
        the corresponding value mapped to the colorbox range.  A
        palette color value can also be read from an explicitly speci-
        fied input column in the uussiinngg specifier.  See ccoolloorrss, sseett
        ppaalleettttee, lliinneettyyppee.

        The keyword nnoohhiiddddeenn33dd applies only to plots made with the
        sspplloott command.  Normally the global option sseett hhiiddddeenn33dd applies
        to all plots in the graph.  You can attach the nnoohhiiddddeenn33dd










   GNUPLOT 4.1                                                      112


        option to any individual plots that you want to exclude from
        the hidden3d processing.  The individual elements other than
        surfaces (i.e. lines, dots, labels, ...) of a plot marked
        nnoohhiiddddeenn33dd will all be drawn, even if they would normally be
        obscured by other plot elements.

        Similarly, the keyword nnooccoonnttoouurrss will turn off contouring for
        an individual plot even if the global property sseett ccoonnttoouurr is
        active.

        Similarly, the keyword nnoossuurrffaaccee will turn off the 3D surface
        for an individual plot even if the global property sseett ssuurrffaaccee
        is active.

        The keywords may be abbreviated as indicated.

        Note that the lliinneewwiiddtthh, ppooiinnttssiizzee and ppaalleettttee options are not
        supported by all terminals.

        Examples:

        This plots sin(x) with impulses:
              plot sin(x) with impulses

        This plots x with points, x**2 with the default:
              plot x w points, x**2

        This plots tan(x) with the default function style, file
        "data.1" with lines:
              plot [ ] [-2:5] tan(x), 'data.1' with l

        This plots "leastsq.dat" with impulses:
              plot 'leastsq.dat' w i

        This plots the data file "population" with boxes:
              plot 'population' with boxes

        This plots "exper.dat" with errorbars and lines connecting the
        points (errorbars require three or four columns):
              plot 'exper.dat' w lines, 'exper.dat' notitle w errorbars

        Another way to plot "exper.dat" with errorlines (errorbars
        require three or four columns):
              plot 'exper.dat' w errorlines

        This plots sin(x) and cos(x) with linespoints, using the same
        line type but different point types:
              plot sin(x) with linesp lt 1 pt 3, cos(x) with linesp lt
        1 pt 4

        This plots file "data" with points of type 3 and twice usual
        size:
              plot 'data' with points pointtype 3 pointsize 2










   GNUPLOT 4.1                                                      113


        This plots file "data" with variable pointsize read from column
        4
              plot 'data' using 1:2:4 with points pt 5 pointsize vari-
        able

        This plots two data sets with lines differing only by weight:
              plot 'd1' t "good" w l lt 2 lw 3, 'd2' t "bad" w l lt 2
        lw 1

        This plots filled curve of x*x and a color stripe:
              plot x*x with filledcurve closed, 40 with filledcurve
        y1=10

        This plots x*x and a color box:
              plot x*x, (x>=-5 && x<=5 ? 40 : 1/0) with filledcurve
        y1=10 lt 8

        This plots a surface with color lines:
              splot x*x-y*y with line palette

        This plots two color surfaces at different altitudes:
              splot x*x-y*y with pm3d, x*x+y*y with pm3d at t




   6699..  PPrriinntt


   The pprriinntt command prints the value of <expression> to the screen.
   It is synonymous with ppaauussee 00.  <expression> may be anything that
   ggnnuupplloott can evaluate that produces a number, or it can be a string.

   Syntax:
         print <expression> {, <expression>, ...}

   See eexxpprreessssiioonnss.  The output file can be set with sseett pprriinntt.



   7700..  PPwwdd


   The ppwwdd command prints the name of the working directory to the
   screen.

   Note that if you wish to store the current directory into a string
   variable or use it in string expressions, then you can use variable
   GPVAL_PWD, see sshhooww vvaarriiaabblleess aallll. This overcomes shell call by
   means of "ppwwdd".













   GNUPLOT 4.1                                                      114


   7711..  QQuuiitt


   The eexxiitt and qquuiitt commands and END-OF-FILE character will exit ggnnuu--
   pplloott.  Each of these commands will clear the output device (as does
   the cclleeaarr command) before exiting.



   7722..  RRaaiissee


   Syntax:
         raise {plot_window_nb}

   The rraaiissee command raises (opposite to lloowweerr) plot window(s) associ-
   ated with the interactive terminal of your gnuplot session, i.e. ppmm,
   wwiinn, wwxxtt or xx1111. It puts the plot window to front (top) in the z-
   order windows stack of the window manager of your desktop.

   As xx1111 and wwxxtt support multiple plot windows, then by default they
   raise these windows in descending order of most recently created on
   top to the least recently created on bottom. If a plot number is
   supplied as an optional parameter, only the associated plot window
   will be raised if it exists.

   The optional parameter is ignored for single plot-windows terminal,
   i.e. ppmm and wwiinn.

   If the window is not raised under X11, then perhaps the plot window
   is running in a different X11 session (telnet or ssh session, for
   example), or perhaps raising is blocked by your window manager pol-
   icy setting.



   7733..  RReeffrreesshh


   The rreeffrreesshh command is similar to rreepplloott, with two major differ-
   ences.  rreeffrreesshh reformats and redraws the current plot using the
   data already read in. This means that you can use rreeffrreesshh for plots
   with in-line data (pseudo-device '-') and for plots from datafiles
   whose contents are volatile.  You cannot use the rreeffrreesshh command to
   add new data to an existing plot.

   Mousing operations, in particular zoom and unzoom, will use rreeffrreesshh
   rather than rreepplloott if appropriate.  Example:

         plot 'datafile' volatile with lines, '-' with labels
         100 200 "Special point"
         e
         # Various mousing operations go here










   GNUPLOT 4.1                                                      115


         set title "Zoomed in view"
         set term post
         set output 'zoom.ps'
         refresh




   7744..  RReepplloott


   The rreepplloott command without arguments repeats the last pplloott or sspplloott
   command.  This can be useful for viewing a plot with different sseett
   options, or when generating the same plot for several devices.

   Arguments specified after a rreepplloott command will be added onto the
   last pplloott or sspplloott command (with an implied ',' separator) before it
   is repeated.  rreepplloott accepts the same arguments as the pplloott and
   sspplloott commands except that ranges cannot be specified.  Thus you can
   use rreepplloott to plot a function against the second axes if the previ-
   ous command was pplloott but not if it was sspplloott.

   N.B.---use of

         plot '-' ; ... ; replot

   is not recommended, because it will require that you type in the
   data all over again.  In most cases you can use the rreeffrreesshh command
   instead, which will redraw the plot using the data previously read
   in.

   Note that rreepplloott does not work in mmuullttiipplloott mode, since it repro-
   duces only the last plot rather than the entire screen.

   See also ccoommmmaanndd--lliinnee--eeddiittiinngg for ways to edit the last pplloott (sspplloott)
   command.

   See also sshhooww pplloott to show the whole current plotting command, and
   the possibility to copy it into the hhiissttoorryy.



   7755..  RReerreeaadd


   The rreerreeaadd command causes the current ggnnuupplloott command file, as spec-
   ified by a llooaadd command or on the command line, to be reset to its
   starting point before further commands are read from it.  This
   essentially implements an endless loop of the commands from the
   beginning of the command file to the rreerreeaadd command.  (But this is
   not necessarily a disaster---rreerreeaadd can be very useful when used in
   conjunction with iiff.  See iiff for details.)  The rreerreeaadd command has
   no effect if input from standard input.










   GNUPLOT 4.1                                                      116


   Examples:

   Suppose the file "looper" contains the commands
         a=a+1
         plot sin(x*a)
         pause -1
         if(a<5) reread
   and from within ggnnuupplloott you submit the commands
         a=0
         load 'looper'
   The result will be five plots (separated by the ppaauussee message).

   Suppose the file "data" contains six columns of numbers with a total
   yrange from 0 to 10; the first is x and the next are five different
   functions of x.  Suppose also that the file "plotter" contains the
   commands
         c_p = c_p+1
         plot "$0" using 1:c_p with lines linetype c_p
         if(c_p <  n_p) reread
   and from within ggnnuupplloott you submit the commands
         n_p=6
         c_p=1
         unset key
         set yrange [0:10]
         set multiplot
         call 'plotter' 'data'
         unset multiplot
   The result is a single graph consisting of five plots.  The yrange
   must be set explicitly to guarantee that the five separate graphs
   (drawn on top of each other in multiplot mode) will have exactly the
   same axes.  The linetype must be specified; otherwise all the plots
   would be drawn with the same type.  See animate.dem in demo direc-
   tory for an animated example.




   7766..  RReesseett


   The rreesseett command causes all graph-related options that can be set
   with the sseett command to take on their default values.  This command
   is useful, e.g., to restore the default graph settings at the end of
   a command file, or to return to a defined state after lots of set-
   tings have been changed within a command file.  Please refer to the
   sseett command to see the default values that the various options take.

   The following are _not_ affected by rreesseett.
        `set term` `set output` `set loadpath` `set fontpath`
        `set encoding` `set decimalsign` `set locale`

   rreesseett eerrrroorrss clears only the error state variables GPVAL_ERRNO and
   GPVAL_ERRMSG.










   GNUPLOT 4.1                                                      117


   rreesseett bbiinndd restores all hotkey bindings to their default state.



   7777..  SSaavvee


   The ssaavvee command saves user-defined functions, variables, the sseett
   tteerrmm status, all sseett options, or all of these, plus the last pplloott
   (sspplloott) command to the specified file.

   Syntax:
         save  {<option>} '<filename>'

   where <option> is ffuunnccttiioonnss, vvaarriiaabblleess, tteerrmmiinnaall or sseett. If no
   option is used, ggnnuupplloott saves functions, variables, sseett options and
   the last pplloott (sspplloott) command.

   ssaavveed files are written in text format and may be read by the llooaadd
   command. For ssaavvee with the sseett option or without any option, the
   tteerrmmiinnaall choice and the oouuttppuutt filename are written out as a com-
   ment, to get an output file that works in other installations of
   gnuplot, without changes and without risk of unwillingly overwriting
   files.

   ssaavvee tteerrmmiinnaall will write out just the tteerrmmiinnaall status, without the
   comment marker in front of it. This is mainly useful for switching
   the tteerrmmiinnaall setting for a short while, and getting back to the pre-
   viously set terminal, afterwards, by loading the saved tteerrmmiinnaall sta-
   tus. Note that for a single gnuplot session you may rather use the
   other method of saving and restoring current terminal by the com-
   mands sseett tteerrmm ppuusshh and sseett tteerrmm ppoopp, see sseett tteerrmm.

   The filename must be enclosed in quotes.

   The special filename "-" may be used to ssaavvee commands to standard
   output.  On systems which support a popen function (Unix), the out-
   put of save can be piped through an external program by starting the
   file name with a '|'.  This provides a consistent interface to ggnnuu--
   pplloott's internal settings to programs which communicate with ggnnuupplloott
   through a pipe.  Please see help for bbaattcchh//iinntteerraaccttiivvee for more
   details.

   Examples:
         save 'work.gnu'
         save functions 'func.dat'
         save var 'var.dat'
         save set 'options.dat'
         save term 'myterm.gnu'
         save '-'
         save '|grep title >t.gp'












   GNUPLOT 4.1                                                      118


   7788..  SSeett--sshhooww


   The sseett command can be used to set _lots_ of options.  No screen is
   drawn, however, until a pplloott, sspplloott, or rreepplloott command is given.

   The sshhooww command shows their settings;  sshhooww aallll shows all the set-
   tings.

   Options changed using sseett can be returned to the default state by
   giving the corresponding uunnsseett command.  See also the rreesseett command,
   which returns all settable parameters to default values.

   If a variable contains time/date data, sshhooww will display it accord-
   ing to the format currently defined by sseett ttiimmeeffmmtt, even if that was
   not in effect when the variable was initially defined.  The sseett and
   uunnsseett commands may optionally contain an iteration clause.  See
   iitteerraattiioonn.





        7788..11..  AAnngglleess


        By default, ggnnuupplloott assumes the independent variable in polar
        graphs is in units of radians.  If sseett aanngglleess ddeeggrreeeess is speci-
        fied before sseett ppoollaarr, then the default range is [0:360] and
        the independent variable has units of degrees.  This is partic-
        ularly useful for plots of data files.  The angle setting also
        applies to 3D mapping as set via the sseett mmaappppiinngg command.

        Syntax:
              set angles {degrees | radians}
              show angles

        The angle specified in sseett ggrriidd ppoollaarr is also read and dis-
        played in the units specified by sseett aanngglleess.

        sseett aanngglleess also affects the arguments of the machine-defined
        functions sin(x), cos(x) and tan(x), and the outputs of
        asin(x), acos(x), atan(x), atan2(x), and arg(x).  It has no
        effect on the arguments of hyperbolic functions or Bessel func-
        tions.  However, the output arguments of inverse hyperbolic
        functions of complex arguments are affected; if these functions
        are used, sseett aanngglleess rraaddiiaannss must be in effect to maintain con-
        sistency between input and output arguments.

              x={1.0,0.1}
              set angles radians
              y=sinh(x)
              print y         #prints {1.16933, 0.154051}










   GNUPLOT 4.1                                                      119


              print asinh(y)  #prints {1.0, 0.1}
        but
              set angles degrees
              y=sinh(x)
              print y         #prints {1.16933, 0.154051}
              print asinh(y)  #prints {57.29578, 5.729578}
        See also poldat.dem: polar plot using sseett aanngglleess demo.



        7788..22..  AArrrrooww


        Arbitrary arrows can be placed on a plot using the sseett aarrrrooww
        command.

        Syntax:
              set arrow {<tag>} {from <position>} {to|rto <position>}
                        { {arrowstyle | as <arrow_style>}
                          | { {nohead | head | backhead | heads}
                              {size <length>,<angle>{,<backangle>}}
                              {filled | empty | nofilled}
                              {front | back}
                              { {linestyle | ls <line_style>}
                                | {linetype | lt <line_type>}
                                  {linewidth | lw <line_width} } } }

              unset arrow {<tag>}
              show arrow {<tag>}

        <tag> is an integer that identifies the arrow.  If no tag is
        given, the lowest unused tag value is assigned automatically.
        The tag can be used to delete or change a specific arrow.  To
        change any attribute of an existing arrow, use the sseett aarrrrooww
        command with the appropriate tag and specify the parts of the
        arrow to be changed.

        The <position>s are specified by either x,y or x,y,z, and may
        be preceded by ffiirrsstt, sseeccoonndd, ggrraapphh, ssccrreeeenn, or cchhaarraacctteerr to
        select the coordinate system.  Unspecified coordinates default
        to 0.  The end points can be specified in one of five coordi-
        nate systems---ffiirrsstt or sseeccoonndd axes, ggrraapphh, ssccrreeeenn, or cchhaarraacc--
        tteerr.  See ccoooorrddiinnaatteess for details.  A coordinate system speci-
        fier does not carry over from the "from" position to the "to"
        position.  Arrows outside the screen boundaries are permitted
        but may cause device errors.  If the end point is specified by
        "rto" instead of "to" it is drawn relatively to the start
        point.  For linear axes, ggrraapphh and ssccrreeeenn coordinates, the dis-
        tance between the start and the end point corresponds to the
        given relative coordinate.  For logarithmic axes, the relative
        given coordinate corresponds to the factor of the coordinate
        between start and end point.  Thus, a negative relative value
        or zero are not allowed for logarithmic axes.










   GNUPLOT 4.1                                                      120


        Specifying nnoohheeaadd produces an arrow drawn without a head---a
        line segment.  This gives you yet another way to draw a line
        segment on the plot.  By default, an arrow has a head at its
        end. Specifying bbaacckkhheeaadd draws an arrow head at the start point
        of the arrow while hheeaaddss draws arrow heads on both ends of the
        line.  Not all terminal types support double-ended arrows.

        Head size can be controlled by ssiizzee <<lleennggtthh>>,,<<aannggllee>> or ssiizzee
        <<lleennggtthh>>,,<<aannggllee>>,,<<bbaacckkaannggllee>>, where <<lleennggtthh>> defines length of
        each branch of the arrow head and <<aannggllee>> the angle (in
        degrees) they make with the arrow.  <<LLeennggtthh>> is in x-axis
        units; this can be changed by ffiirrsstt, sseeccoonndd, ggrraapphh, ssccrreeeenn, or
        cchhaarraacctteerr before the <length>;  see ccoooorrddiinnaatteess for details.
        <<BBaacckkaannggllee>> only takes effect when ffiilllleedd or eemmppttyy is also
        used.  Then, <<bbaacckkaannggllee>> is the angle (in degrees) the back
        branches make with the arrow (in the same direction as
        <<aannggllee>>).  The ffiigg terminal has a restricted backangle func-
        tion. It supports three different angles. There are two thresh-
        olds: Below 70 degrees, the arrow head gets an indented back
        angle. Above 110 degrees, the arrow head has an acute back
        angle. Between these thresholds, the back line is straight.

        Specifying ffiilllleedd produces filled arrow heads (if heads are
        used).  Filling is supported on filled-polygon capable termi-
        nals, see help of ppmm33dd for their list, otherwise the arrow
        heads are closed but not filled.  The same result (closed but
        not filled arrow head) is reached by specifying eemmppttyy.  Fur-
        ther, filling and outline is obviously not supported on termi-
        nals drawing arrows by their own specific routines, like mmeettaa--
        ffoonntt, mmeettaappoosstt, llaatteexx or ttggiiff.

        The line style may be selected from a user-defined list of line
        styles (see sseett ssttyyllee lliinnee) or may be defined here by providing
        values for <line_type> (an index from the default list of
        styles) and/or <line_width> (which is a  multiplier for the
        default width).

        Note, however, that if a user-defined line style has been
        selected, its properties (type and width) cannot be altered
        merely by issuing another sseett aarrrrooww command with the appropri-
        ate index and lltt or llww.

        If ffrroonntt is given, the arrow is written on top of the graphed
        data. If bbaacckk is given (the default), the arrow is written
        underneath the graphed data.  Using ffrroonntt will prevent an arrow
        from being obscured by dense data.

        Examples:

        To set an arrow pointing from the origin to (1,2) with user-
        defined style 5, use:
              set arrow to 1,2 ls 5











   GNUPLOT 4.1                                                      121


        To set an arrow from bottom left of plotting area to (-5,5,3),
        and tag the arrow number 3, use:
              set arrow 3 from graph 0,0 to -5,5,3

        To change the preceding arrow to end at 1,1,1, without an arrow
        head and double its width, use:
              set arrow 3 to 1,1,1 nohead lw 2

        To draw a vertical line from the bottom to the top of the graph
        at x=3, use:
              set arrow from 3, graph 0 to 3, graph 1 nohead

        To draw a vertical arrow with T-shape ends, use:
              set arrow 3 from 0,-5 to 0,5 heads size screen 0.1,90

        To draw an arrow relatively to the start point, where the rela-
        tive distances are given in graph coordinates, use:
              set arrow from 0,-5 rto graph 0.1,0.1

        To draw an arrow with relative end point in logarithmic x axis,
        use:
              set logscale x
              set arrow from 100,-5 rto 10,10
        This draws an arrow from 100,-5 to 1000,5. For the logarithmic
        x axis, the relative coordinate 10 means "factor 10" while for
        the linear y axis, the relative coordinate 10 means "difference
        10".

        To delete arrow number 2, use:
              unset arrow 2

        To delete all arrows, use:
              unset arrow

        To show all arrows (in tag order), use:
              show arrow

        arrows demos.




        7788..33..  AAuuttoossccaallee


        Autoscaling may be set individually on the x, y or z axis or
        globally on all axes. The default is to autoscale all axes.  If
        you want to autoscale based on a subset of the plots in the
        figure, you can mark the other ones with the flag nnooaauuttoossccaallee.
        See ddaattaaffiillee.

        Syntax:
              set autoscale {<axes>{|min|max|fixmin|fixmax|fix} | fix |










   GNUPLOT 4.1                                                      122


        keepfix}
              unset autoscale {<axes>}
              show autoscale

        where <axes> is either xx, yy, zz, ccbb, xx22, yy22 or xxyy.  A keyword
        with mmiinn or mmaaxx appended (this cannot be done with xxyy) tells
        ggnnuupplloott to autoscale just the minimum or maximum of that axis.
        If no keyword is given, all axes are autoscaled.

        A keyword with ffiixxmmiinn, ffiixxmmaaxx or ffiixx appended tells gnuplot to
        disable extension of the axis range to the next tic mark posi-
        tion, for autoscaled axes using equidistant tics; sseett aauuttoossccaallee
        ffiixx sets this for all axes.  Command sseett aauuttoossccaallee kkeeeeppffiixx
        autoscales all axes while keeping the fix settings.

        When autoscaling, the axis range is automatically computed and
        the dependent axis (y for a pplloott and z for sspplloott) is scaled to
        include the range of the function or data being plotted.

        If autoscaling of the dependent axis (y or z) is not set, the
        current y or z range is used.

        Autoscaling the independent variables (x for pplloott and x,y for
        sspplloott) is a request to set the domain to match any data file
        being plotted.  If there are no data files, autoscaling an
        independent variable has no effect.  In other words, in the
        absence of a data file, functions alone do not affect the x
        range (or the y range if plotting z = f(x,y)).

        Please see sseett xxrraannggee for additional information about ranges.

        The behavior of autoscaling remains consistent in parametric
        mode, (see sseett ppaarraammeettrriicc).  However, there are more dependent
        variables and hence more control over x, y, and z axis scales.
        In parametric mode, the independent or dummy variable is t for
        ppllootts and u,v for ssppllootts.  aauuttoossccaallee in parametric mode, then,
        controls all ranges (t, u, v, x, y, and z) and allows x, y, and
        z to be fully autoscaled.

        Autoscaling works the same way for polar mode as it does for
        parametric mode for pplloott, with the extension that in polar mode
        sseett dduummmmyy can be used to change the independent variable from t
        (see sseett dduummmmyy).

        When tics are displayed on second axes but no plot has been
        specified for those axes, x2range and y2range are inherited
        from xrange and yrange.  This is done _before_ xrange and
        yrange are autoextended to a whole number of tics, which can
        cause unexpected results.  You can use the ffiixxmmiinn or ffiixxmmaaxx
        options to avoid this.

        Examples:











   GNUPLOT 4.1                                                      123


        This sets autoscaling of the y axis (other axes are not
        affected):
              set autoscale y

        This sets autoscaling only for the minimum of the y axis (the
        maximum of the y axis and the other axes are not affected):
              set autoscale ymin

        This disables extension of the x2 axis tics to the next tic
        mark, thus keeping the exact range as found in the plotted data
        and functions:
              set autoscale x2fixmin
              set autoscale x2fixmax

        This sets autoscaling of the x and y axes:
              set autoscale xy

        This sets autoscaling of the x, y, z, x2 and y2 axes:
              set autoscale

        This disables autoscaling of the x, y, z, x2 and y2 axes:
              unset autoscale

        This disables autoscaling of the z axis only:
              unset autoscale z




             7788..33..11..  PPaarraammeettrriicc mmooddee


             When in parametric mode (sseett ppaarraammeettrriicc), the xrange is as
             fully scalable as the y range.  In other words, in para-
             metric mode the x axis can be automatically scaled to fit
             the range of the parametric function that is being plot-
             ted.  Of course, the y axis can also be automatically
             scaled just as in the non-parametric case.  If autoscaling
             on the x axis is not set, the current x range is used.

             Data files are plotted the same in parametric and non-
             parametric mode.  However, there is a difference in mixed
             function and data plots: in non-parametric mode with
             autoscaled x, the x range of the datafile controls the x
             range of the functions; in parametric mode it has no
             influence.

             For completeness a last command sseett aauuttoossccaallee tt is
             accepted.  However, the effect of this "scaling" is very
             minor.  When ggnnuupplloott determines that the t range would be
             empty, it makes a small adjustment if autoscaling is true.
             Otherwise, ggnnuupplloott gives an error.  Such behavior may, in
             fact, not be very useful and the command sseett aauuttoossccaallee tt










   GNUPLOT 4.1                                                      124


             is certainly questionable.

             sspplloott extends the above ideas as you would expect.  If
             autoscaling is set, then x, y, and z ranges are computed
             and each axis scaled to fit the resulting data.



             7788..33..22..  PPoollaarr mmooddee


             When in polar mode (sseett ppoollaarr), the xrange and the yrange
             are both found from the polar coordinates, and thus they
             can both be automatically scaled.  In other words, in
             polar mode both the x and y axes can be automatically
             scaled to fit the ranges of the polar function that is
             being plotted.

             When plotting functions in polar mode, the rrange may be
             autoscaled.  When plotting data files in polar mode, the
             trange may also be autoscaled.  Note that if the trange is
             contained within one quadrant, autoscaling will produce a
             polar plot of only that single quadrant.

             Explicitly setting one or two ranges but not others may
             lead to unexpected results.  See also polar demos.



        7788..44..  BBaarrss


        The sseett bbaarrss command controls the tics at the ends of error
        bars.

        Syntax:
              set bars {small | large | fullwidth | <size>} {front |
        back}
              unset bars
              show bars

        ssmmaallll is a synonym for 0.0, and llaarrggee for 1.0.  The default is
        1.0 if no size is given.

        The keyword ffuullllwwiiddtthh is relevant only to histograms with
        errorbars.  It sets the width of the errorbar ends to be the
        same as the width of the associated box in the histogram.  It
        does not change the width of the box itself.

        The ffrroonntt and bbaacckk keywords are relevant only to errorbars
        attached to filled rectangles (boxes, candlesticks, his-
        tograms).











   GNUPLOT 4.1                                                      125


        7788..55..  BBiinndd


        Show the current state of all hotkey bindings. See bbiinndd.



        7788..66..  BBmmaarrggiinn


        The command sseett bbmmaarrggiinn sets the size of the bottom margin.
        Please see sseett mmaarrggiinn for details.



        7788..77..  BBoorrddeerr


        The sseett bboorrddeerr and uunnsseett bboorrddeerr commands control the display of
        the graph borders for the pplloott and sspplloott commands.  Note that
        the borders do not necessarily coincide with the axes; with
        pplloott they often do, but with sspplloott they usually do not.

        Syntax:
              set border {<integer>} {front | back} {linewidth | lw
        <line_width>}
                         {{linestyle | ls <line_style>} | {linetype |
        lt <line_type>}}
              unset border
              show border

        With a sspplloott displayed in an arbitrary orientation, like sseett
        vviieeww 5566,,110033, the four corners of the x-y plane can be referred
        to as "front", "back", "left" and "right".  A similar set of
        four corners exist for the top surface, of course.  Thus the
        border connecting, say, the back and right corners of the x-y
        plane is the "bottom right back" border, and the border con-
        necting the top and bottom front corners is the "front verti-
        cal".  (This nomenclature is defined solely to allow the reader
        to figure out the table that follows.)

        The borders are encoded in a 12-bit integer: the bottom four
        bits control the border for pplloott and the sides of the base for
        sspplloott; the next four bits control the verticals in sspplloott; the
        top four bits control the edges on top of the sspplloott.  In
        detail, <<iinntteeggeerr>> should be the sum of the appropriate entries
        from the following table:
















   GNUPLOT 4.1                                                      126


                 +--------------------------------------+
                 |Bit      plot            splot        |
                 +--------------------------------------+
                 | 1      bottom     bottom left front  |
                 | 2       left       bottom left back  |
                 | 4        top      bottom right front |
                 | 8       right     bottom right back  |
                 | 16    no effect     left vertical    |
                 | 32    no effect     back vertical    |
                 | 64    no effect     right vertical   |
                 |128    no effect     front vertical   |
                 |256    no effect     top left back    |
                 |512    no effect     top right back   |
                 |1024   no effect     top left front   |
                 |2048   no effect    top right front   |
                 +--------------------------------------+



   Various bits or combinations of bits may be added together in the
   command.

   The default is 31, which is all four sides for pplloott, and base and z
   axis for sspplloott.

   In 2D plots the border is normally drawn on top of all plots ele-
   ments (ffrroonntt). If you want the border to be drawn behind the plot
   elements, use sseett bboorrddeerr bbaacckk.

   Using the optional <line_style>, <line_type> and <line_width> speci-
   fiers, the way the border lines are drawn can be influenced (limited
   by what the current terminal driver supports).

   For pplloott, tics may be drawn on edges other than bottom and left by
   enabling the second axes -- see sseett xxttiiccss for details.

   If a sspplloott draws only on the base, as is the case with "uunnsseett ssuurr--
   ffaaccee;; sseett ccoonnttoouurr bbaassee", then the verticals and the top are not
   drawn even if they are specified.

   The sseett ggrriidd options 'back', 'front' and 'layerdefault' also control
   the order in which the border lines are drawn with respect to the
   output of the plotted data.

   Examples:

   Draw default borders:
         set border

   Draw only the left and bottom (pplloott) or both front and back bottom
   left (sspplloott) borders:
         set border 3











   GNUPLOT 4.1                                                      127


   Draw a complete box around a sspplloott:
         set border 4095

   Draw a topless box around a sspplloott, omitting the front vertical:
         set border 127+256+512 # or set border 1023-128

   Draw only the top and right borders for a pplloott and label them as
   axes:
         unset xtics; unset ytics; set x2tics; set y2tics; set border
   12




        7788..88..  BBooxxwwiiddtthh


        The sseett bbooxxwwiiddtthh command is used to set the default width of
        boxes in the bbooxxeess, bbooxxeerrrroorrbbaarrss, ccaannddlleessttiicckkss and hhiissttooggrraammss
        styles.

        Syntax:
              set boxwidth {<width>} {absolute|relative}
              show boxwidth

        By default, adjacent boxes are extended in width until they
        touch each other.  A different default width may be specified
        using the sseett bbooxxwwiiddtthh command.  RReellaattiivvee widths are inter-
        preted as being a fraction of this default width.

        An explicit value for the boxwidth is interpreted as being a
        number of units along the current x axis (aabbssoolluuttee) unless the
        modifier rreellaattiivvee is given.  If the x axis is a log-scale (see
        sseett lloogg) then the value of boxwidth is truly "absolute" only at
        x=1; this physical width is maintained everywhere along the
        axis (i.e. the boxes do not become narrower the value of x
        increases). If the range spanned by a log scale x axis is far
        from x=1, some experimentation may be required to find a useful
        value of boxwidth.

        The default is superseded by explicit width information taken
        from an extra data column in styles bbooxxeess or bbooxxeerrrroorrbbaarrss.  In
        a four-column data set, the fourth column will be interpreted
        as the box width unless the width is set to -2.0, in which case
        the width will be calculated automatically.  See ssttyyllee bbooxxeess
        and ssttyyllee bbooxxeerrrroorrbbaarrss for more details.

        To set the box width to automatic use the command
              set boxwidth

        or, for four-column data,
              set boxwidth -2











   GNUPLOT 4.1                                                      128


        The same effect can be achieved with the uussiinngg keyword in pplloott:
              plot 'file' using 1:2:3:4:(-2)

        To set the box width to half of the automatic size use
              set boxwidth 0.5 relative

        To set the box width to an absolute value of 2 use
              set boxwidth 2 absolute



        7788..99..  CCllaabbeell


        ggnnuupplloott will vary the linetype used for each contour level when
        clabel is set.  When this option on (the default), a legend
        labels each linestyle with the z level it represents.  It is
        not possible at present to separate the contour labels from the
        surface key.

        Syntax:
              set clabel {'<format>'}
              unset clabel
              show clabel

        The default for the format string is %8.3g, which gives three
        decimal places.  This may produce poor label alignment if the
        key is altered from its default configuration.

        The first contour linetype, or only contour linetype when cla-
        bel is off, is the surface linetype +1; contour points are the
        same style as surface points.

        See also sseett ccoonnttoouurr.



        7788..1100..  CClliipp


        ggnnuupplloott can clip data points and lines that are near the bound-
        aries of a graph.

        Syntax:
              set clip <clip-type>
              unset clip <clip-type>
              show clip

        Three clip types for points and lines are supported by ggnnuupplloott:
        ppooiinnttss, oonnee, and ttwwoo. One, two, or all three clip types may be
        active for a single graph.  Note that clipping of color filled
        quadrangles drawn by ppmm33dd maps and surfaces is not controlled
        by this command, but by sseett ppmm33dd cclliipp11iinn and sseett ppmm33dd cclliipp44iinn.










   GNUPLOT 4.1                                                      129


        The ppooiinnttss clip type forces ggnnuupplloott to clip (actually, not plot
        at all) data points that fall within but too close to the
        boundaries.  This is done so that large symbols used for points
        will not extend outside the boundary lines.  Without clipping
        points near the boundaries, the plot may look bad.  Adjusting
        the x and y ranges may give similar results.

        Setting the oonnee clip type causes ggnnuupplloott to draw a line segment
        which has only one of its two endpoints within the graph.  Only
        the in-range portion of the line is drawn.  The alternative is
        to not draw any portion of the line segment.

        Some lines may have both endpoints out of range, but pass
        through the graph.  Setting the ttwwoo clip-type allows the visi-
        ble portion of these lines to be drawn.

        In no case is a line drawn outside the graph.

        The defaults are nnoocclliipp ppooiinnttss, cclliipp oonnee, and nnoocclliipp ttwwoo.

        To check the state of all forms of clipping, use
              show clip

        For backward compatibility with older versions, the following
        forms are also permitted:
              set clip
              unset clip

        sseett cclliipp is synonymous with sseett cclliipp ppooiinnttss; uunnsseett cclliipp turns
        off all three types of clipping.



        7788..1111..  CCnnttrrppaarraamm


        sseett ccnnttrrppaarraamm controls the generation of contours and their
        smoothness for a contour plot. sshhooww ccoonnttoouurr displays current
        settings of ccnnttrrppaarraamm as well as ccoonnttoouurr.

        Syntax:
              set cntrparam { { linear
                              | cubicspline
                              | bspline
                              | points <n>
                              | order <n>
                              | levels { auto {<n>} | <n>
                                         | discrete <z1>
        {,<z2>{,<z3>...}}
                                         | incremental <start>, <incr>
        {,<end>}
                                       }
                              }










   GNUPLOT 4.1                                                      130


                            }
              show contour

        This command has two functions.  First, it sets the values of z
        for which contour points are to be determined (by linear inter-
        polation between data points or function isosamples.)  Second,
        it controls the way contours are drawn between the points
        determined to be of equal z.  <n> should be an integral con-
        stant expression and <z1>, <z2> ... any constant expressions.
        The parameters are:

        lliinneeaarr, ccuubbiiccsspplliinnee, bbsspplliinnee---Controls type of approximation
        or interpolation.  If lliinneeaarr, then straight line segments con-
        nect points of equal z magnitude.  If ccuubbiiccsspplliinnee, then piece-
        wise-linear contours are interpolated between the same equal z
        points to form somewhat smoother contours, but which may undu-
        late.  If bbsspplliinnee, a guaranteed-smoother curve is drawn, which
        only approximates the position of the points of equal-z.

        ppooiinnttss---Eventually all drawings are done with piecewise-linear
        strokes.  This number controls the number of line segments used
        to approximate the bbsspplliinnee or ccuubbiiccsspplliinnee curve.  Number of
        cubicspline or bspline segments (strokes) = ppooiinnttss * number of
        linear segments.

        oorrddeerr---Order of the bspline approximation to be used.  The
        bigger this order is, the smoother the resulting contour.  (Of
        course, higher order bspline curves will move further away from
        the original piecewise linear data.)  This option is relevant
        for bbsspplliinnee mode only.  Allowed values are integers in the
        range from 2 (linear) to 10.

        lleevveellss--- Selection of contour levels,  controlled by aauuttoo
        (default), ddiissccrreettee, iinnccrreemmeennttaall, and <n>, number of contour
        levels.

        For aauuttoo, <n> specifies a nominal number of levels; the actual
        number will be adjusted to give simple labels. If the surface
        is bounded by zmin and zmax, contours will be generated at
        integer multiples of dz between zmin and zmax, where dz is 1,
        2, or 5 times some power of ten (like the step between two tic
        marks).

        For lleevveellss ddiissccrreettee, contours will be generated at z = <z1>,
        <z2> ... as specified; the number of discrete levels sets the
        number of contour levels.  In ddiissccrreettee mode, any sseett ccnnttrrppaarraamm
        lleevveellss <<nn>> are ignored.

        For iinnccrreemmeennttaall, contours are generated at values of z begin-
        ning at <start> and increasing by <increment>, until the number
        of contours is reached. <end> is used to determine the number
        of contour levels, which will be changed by any subsequent sseett
        ccnnttrrppaarraamm lleevveellss <<nn>>.  If the z axis is logarithmic,










   GNUPLOT 4.1                                                      131


        <increment> will be interpreted as a factor, just like in sseett
        zzttiiccss.

        If the command sseett ccnnttrrppaarraamm is given without any arguments
        specified,  the defaults are used: linear, 5 points, order 4, 5
        auto levels.

        Examples:
              set cntrparam bspline
              set cntrparam points 7
              set cntrparam order 10

        To select levels automatically, 5 if the level increment crite-
        ria are met:
              set cntrparam levels auto 5

        To specify discrete levels at .1, .37, and .9:
              set cntrparam levels discrete .1,1/exp(1),.9

        To specify levels from 0 to 4 with increment 1:
              set cntrparam levels incremental  0,1,4

        To set the number of levels to 10 (changing an incremental end
        or possibly the number of auto levels):
              set cntrparam levels 10

        To set the start and increment while retaining the number of
        levels:
              set cntrparam levels incremental 100,50

        See also sseett ccoonnttoouurr for control of where the contours are
        drawn, and sseett ccllaabbeell for control of the format of the contour
        labels and linetypes.

        See also contours demo (contours.dem) and contours with user
        defined levels demo (discrete.dem).



        7788..1122..  CCoolloorr bbooxx



        The color scheme, i.e. the gradient of the smooth color with
        min_z and max_z values of ppmm33dd's ppaalleettttee, is drawn in a color
        box unless uunnsseett ccoolloorrbbooxx.

              set colorbox
              set colorbox {
                         { vertical | horizontal }
                         { default | user }
                         { origin x, y }
                         { size x, y }










   GNUPLOT 4.1                                                      132


                         { front | back }
                         { noborder | bdefault | border [line style] }
                       }
              show colorbox
              unset colorbox

        Color box position can be ddeeffaauulltt or uusseerr.  If the latter is
        specified the values as given with the oorriiggiinn and ssiizzee subcom-
        mands are used. The box can be drawn after (ffrroonntt) or before
        (bbaacckk) the graph or the surface.

        The orientation of the color gradient can be switched by
        options vveerrttiiccaall and hhoorriizzoonnttaall.

        oorriiggiinn xx,, yy and ssiizzee xx,, yy are used only in combination with the
        uusseerr option. The x and y values are interpreted as screen coor-
        dinates by default, and this is the only legal option for 3D
        plots. 2D plots, including splot with sseett vviieeww mmaapp, allow any
        coordinate system to be specified.  Try for example:
            set colorbox horiz user origin .1,.02 size .8,.04
        which will draw a horizontal gradient somewhere at the bottom
        of the graph.

        bboorrddeerr turns the border on (this is the default). nnoobboorrddeerr
        turns the border off. If an positive integer argument is given
        after bboorrddeerr, it is used as a line style tag which is used for
        drawing the border, e.g.:
            set style line 2604 linetype -1 linewidth .4
            set colorbox border 2604
        will use line style 22660044, a thin line with the default border
        color (-1) for drawing the border. bbddeeffaauulltt (which is the
        default) will use the default border line style for drawing the
        border of the color box.

        The axis of the color box is called ccbb and it is controlled by
        means of the usual axes commands, i.e. sseett//uunnsseett//sshhooww with
        ccbbrraannggee, [[mm]]ccbbttiiccss, ffoorrmmaatt ccbb, ggrriidd [[mm]]ccbb, ccbbllaabbeell, and perhaps
        even ccbbddaattaa, [[nnoo]]ccbbddttiiccss, [[nnoo]]ccbbmmttiiccss.

        sseett ccoolloorrbbooxx without any parameter switches the position to
        default.  uunnsseett ccoolloorrbbooxx resets the default parameters for the
        colorbox and switches the colorbox off.

        See also help for sseett ppmm33dd, sseett ppaalleettttee, xx1111 ppmm33dd, and sseett
        ssttyyllee lliinnee.



        7788..1133..  CCoolloorrnnaammeess


        Gnuplot knows a limited number of color names. You can use
        these to define the color range spanned by a pm3d palette, or










   GNUPLOT 4.1                                                      133


        to assign a terminal-independent color to a particular linetype
        or linestyle. To see the list of known color names, use the
        command sshhooww ccoolloorrnnaammeess.   Example:

              set style line 1 linecolor rgb "sea-green"



        7788..1144..  CCoonnttoouurr


        sseett ccoonnttoouurr enables contour drawing for surfaces.  This option
        is available for sspplloott only.  It requires grid data, see
        ggrriidd__ddaattaa for more details.  If contours are desired from non-
        grid data, sseett ddggrriidd33dd can be used to create an appropriate
        grid.

        Syntax:
              set contour {base | surface | both}
              unset contour
              show contour

        The three options specify where to draw the contours: bbaassee
        draws the contours on the grid base where the x/ytics are
        placed, ssuurrffaaccee draws the contours on the surfaces themselves,
        and bbootthh draws the contours on both the base and the surface.
        If no option is provided, the default is bbaassee.

        See also sseett ccnnttrrppaarraamm for the parameters that affect the draw-
        ing of contours, and sseett ccllaabbeell for control of labelling of the
        contours.

        The surface can be switched off (see sseett ssuurrffaaccee), giving a
        contour-only graph.  Though it is possible to use sseett ssiizzee to
        enlarge the plot to fill the screen, more control over the out-
        put format can be obtained by writing the contour information
        to a file, and rereading it as a 2D datafile plot:

              unset surface
              set contour
              set cntrparam ...
              set table 'filename'
              splot ...
              unset table
              # contour info now in filename
              set term <whatever>
              plot 'filename'

        In order to draw contours, the data should be organized as
        "grid data".  In such a file all the points for a single y-iso-
        line are listed, then all the points for the next y-isoline,
        and so on.  A single blank line (a line containing no charac-
        ters other than blank spaces and a carriage return and/or a










   GNUPLOT 4.1                                                      134


        line feed) separates one y-isoline from the next.  See also
        sspplloott ddaattaaffiillee.

        See also contours demo (contours.dem) and contours with user
        defined levels demo (discrete.dem).



        7788..1155..  DDaattaa ssttyyllee


        This form of the command is deprecated. Please see sseett ssttyyllee
        ddaattaa.



        7788..1166..  DDaattaaffiillee


        The sseett ddaattaaffiillee command options control interpretation of
        fields read from input data files by the pplloott, sspplloott, and ffiitt
        commands.  Six such options are currently implemented.




             7788..1166..11..  SSeett ddaattaaffiillee ffoorrttrraann


             The sseett ddaattaaffiillee ffoorrttrraann command enables a special check
             for values in the input file expressed as Fortran D or Q
             constants. This extra check slows down the input process,
             and should only be selected if you do in fact have
             datafiles containing Fortran D or Q constants. The option
             can be disabled again using uunnsseett ddaattaaffiillee ffoorrttrraann.



             7788..1166..22..  SSeett ddaattaaffiillee nnooffppee__ttrraapp


             The sseett ddaattaaffiillee nnooffppee__ttrraapp command tells gnuplot not to
             re-initialize a floating point exception handler before
             every expression evaluation used while reading data from
             an input file.  This can significantly speed data input
             from large files at the risk of program termination if a
             floating-point exception is generated.
















   GNUPLOT 4.1                                                      135


             7788..1166..33..  SSeett ddaattaaffiillee mmiissssiinngg


             The sseett ddaattaaffiillee mmiissssiinngg command allows you to tell ggnnuu--
             pplloott what character string is used in a data file to
             denote missing data.  Exactly how this missing value will
             be treated depends on the uussiinngg specifier of the pplloott or
             sspplloott command.

             Syntax:
                   set datafile missing {"<string>"}
                   show datafile missing
                   unset datafile

             Example:
                   # Ignore entries containing IEEE NaN ("Not a Num-
             ber") code
                   set datafile missing "NaN"

             Example:
                   set style data linespoints
                   plot '-'
                      1 10
                      2 20
                      3 ?
                      4 40
                      5 50
                      e
                   set datafile missing "?"
                   plot '-'
                      1 10
                      2 20
                      3 ?
                      4 40
                      5 50
                      e
                   plot '-' using 1:2
                      1 10
                      2 20
                      3 ?
                      4 40
                      5 50
                      e
                   plot '-' using 1:($2)
                      1 10
                      2 20
                      3 ?
                      4 40
                      5 50
                      e

             The first pplloott will recognize only the first datum in the
             "3 ?" line.  It will use the single-datum-on-a-line










   GNUPLOT 4.1                                                      136


             convention that the line number is "x" and the datum is
             "y", so the point will be plotted (in this case erro-
             neously) at (2,3).

             The second and third pplloott commands will correctly ignore
             the middle line.  The plotted line will connect the points
             at (2,20) and (4,40).

             The fourth pplloott will also correctly ignore the middle
             line, but the plotted line will not connect the points at
             (2,20) and (4,40).

             There is no default character for mmiissssiinngg, but in many
             cases any non-parsible string of characters found where a
             numerical value is expected will be treated as missing
             data.




             7788..1166..44..  SSeett ddaattaaffiillee sseeppaarraattoorr


             The command sseett ddaattaaffiillee sseeppaarraattoorr ""<<cchhaarr>>"" tells ggnnuupplloott
             that data fields in subsequent input files are separated
             by <char> rather than by whitespace.  The most common use
             is to read in csv (comma-separated value) files written by
             spreadsheet or database programs. By default data fields
             are separated by whitespace.

             Syntax:
                   set datafile separator {"<char>" | whitespace}

             Examples:
                   # Input file contains tab-separated fields
                   set datafile separator "\t"

                   # Input file contains comma-separated values fields
                   set datafile separator ","



             7788..1166..55..  SSeett ddaattaaffiillee ccoommmmeennttsscchhaarrss


             The sseett ddaattaaffiillee ccoommmmeennttsscchhaarrss command allows you to tell
             ggnnuupplloott what characters are used in a data file to denote
             comments.  Gnuplot will ignore rest of the line behind the
             specified characters if either of them is the first non-
             blank character on the line.

             Syntax:
                   set datafile commentschars {"<string>"}










   GNUPLOT 4.1                                                      137


                   show datafile commentschars
                   unset commentschars

             Default value of the string is "#!" on VMS and "#" other-
             wise.

             Then, the following line in a data file is completely
             ignored
                 # 1 2 3 4
             but the following
                 1 # 3 4
             produces rather unexpected plot unless
                 set datafile missing '#'
             is specified as well.

             Example:
                   set datafile commentschars "#!%"



             7788..1166..66..  SSeett ddaattaaffiillee bbiinnaarryy


             The sseett ddaattaaffiillee bbiinnaarryy command is used to set the
             defaults when reading binary data files.  The syntax
             matches precisely that used for commands pplloott and sspplloott.
             See bbiinnaarryy for details about <binary list>.

             Syntax:
                   set datafile binary <binary list>
                   show datafile binary
                   show datafile
                   unset datafile

             Examples:
                   set datafile binary filetype=auto
                   set datafile binary array=(512,512) format="%uchar"

                   show datafile binary   # list current settings



        7788..1177..  DDeecciimmaallssiiggnn


        The sseett ddeecciimmaallssiiggnn command selects a decimal sign for numbers
        printed into tic labels or sseett llaabbeell strings.

        Syntax:
              set decimalsign {<value> | locale {"<locale>"}}
              unset decimalsign
              show decimalsign











   GNUPLOT 4.1                                                      138


        The argument <value> is a string to be used in place of the
        usual decimal point. Typical choices include the period, '.',
        and the comma, ',', but others may be useful, too.  If you omit
        the <value> argument, the decimal separator is not modified
        from the usual default, which is a period.  Unsetting decimal-
        sign has the same effect as omitting <value>.

        Example:

        Correct typesetting in most European countries requires:
              set decimalsign ','

        Please note: If you set an explicit string, this affects only
        numbers that are printed using gnuplot's gprintf() formatting
        routine, include axis tics.  It does not affect the format
        expected for input data, and it does not affect numbers printed
        with the sprintf() formatting routine. To change the behavior
        of both input and output formatting, instead use the form

              set decimalsign locale

        This instructs the program to use both input and output formats
        in accordance with the current setting of the LC_ALL,
        LC_NUMERIC, or LANG environmental variables.

              set decimalsign locale "foo"

        This instructs the program to format all input and output in
        accordance with locale "foo", which must be installed.  If
        locale "foo" is not found then an error message is printed and
        the decimal sign setting is unchanged.  On linux systems you
        can get a list of the locales installed on your machine by typ-
        ing "locale -a". A typical linux locale string is of the form
        "sl_SI.UTF-8".  A typical Windows locale string is of the form
        "Slovenian_Slovenia.1250" or "slovenian". Please note that
        interpretation of the locale settings is done by the C library
        at runtime. Older C libraries may offer only partial support
        for locale settings such as the thousands grouping separator
        character.

              set decimalsign locale; set decimalsign "."

        This sets all input and output to use whatever decimal sign is
        correct for the current locale, but over-rides this with an
        explicit '.' in numbers formatted using gnuplot's internal
        gprintf() function.



        7788..1188..  DDggrriidd33dd













   GNUPLOT 4.1                                                      139


        The sseett ddggrriidd33dd command enables, and can set parameters for,
        non-grid to grid data mapping.  See sspplloott ggrriidd__ddaattaa for more
        details about the grid data structure.

        Syntax:
              set dgrid3d {<rows>} {,{<cols>}}
                          { splines |
                            qnorm {<norm>} |
                            (gauss | cauchy | exp | box | hann) {<dx>}
        {,dy} }
              unset dgrid3d
              show dgrid3d

        By default ddggrriidd33dd is disabled.  When enabled, 3D data read
        from a file are always treated as a scattered data set.  A grid
        with dimensions derived from a bounding box of the scattered
        data and size as specified by the row/col_size parameters is
        created for plotting and contouring.  The grid is equally
        spaced in x (rows) and in y (columns); the z values are com-
        puted as weighted averages or spline interpolations of the
        scattered points' z values. In other words, a regularly spaced
        grid is created and the a smooth approximation to the raw data
        is evaluated for all grid points. Only this approximation is
        plotted, but not the raw data.

        The number of columns defaults to the number of rows, which
        defaults to 10.

        Several algorithms are available to calculate the approximation
        from the raw data. Some of these algorithms can take additional
        parameters.  These interpolations are such the closer the data
        point is to a grid point, the more effect it has on that grid
        point.

        The sspplliinneess algorithm calculates an interpolation based on
        "thin plate splines". It does not take additional paramaters.

        The qqnnoorrmm algorithm calculates a weighted average of the input
        data at each grid point. Each data point is weighted inversely
        by its distance from the grid point raised to the norm power.
        (Actually, the weights are given by the inverse of dx^norm +
        dy^norm, where dx and dy are the components of the separation
        of the grid point from each data point.  For some norms that
        are powers of two, specifically 4, 8, and 16, the computation
        is optimized by using the Euclidean distance in the weight cal-
        culation, (dx^2+dy^2)^norm/2.  However, any non-negative inte-
        ger can be used.) The power of the norm can be specified as a
        single optional parameter. This algorithm is the default.

        Finally, several smoothing kernels are available to calculate
        weighted averages: z = Sum_i w(d_i) * z_i / Sum_i w(d_i), where
        z_i is the value of the i-th data point and d_i is the distance
        between the current grid point and the location of the i-th










   GNUPLOT 4.1                                                      140


        data point. All kernels assign higher weights to data points
        that are close to the current grid point and lower weights to
        data points further away.

        The following kernels are available:
              gauss :     w(d) = exp(-d*d)
              cauchy :    w(d) = 1/(1 + d*d)
              exp :       w(d) = exp(-d)
              box :       w(d) = 1                     if d<1
                               = 0                     otherwise
              hann :      w(d) = 0.5*(1-cos(2*pi*d))   if d<1
                          w(d) = 0                     otherwise

        When using one of these five smoothing kernels, up to two addi-
        tional parameter can be specified: dx and dy. These are used to
        rescale the coordinate differences when calculating the dis-
        tance: d_i = sqrt( ((x-x_i)/dx)**2 + ((y-y_i)/dy)**2 ), where
        x,y are the coordinates of the current grid point and x_i,y_i
        are the coordinates of the i-th data point. The value of dy
        defaults to the value of dx, which defaults to 1. The parame-
        ters dx and dy make it possible to control the radius over
        which data points contribute to a grid point IN THE UNITS OF
        THE DATA ITSELF.

        A slightly different syntax is also supported for reasons of
        backwards compatibility. If no interpolation algorithm has been
        explicitly selected, the qqnnoorrmm algorithm is assumed. Up to
        three comma-separated, optional paramaters can be specified,
        which are interpreted as the the number of rows, the number of
        columns, and the norm value, respectively.

        The ddggrriidd33dd option is a simple scheme which replaces scattered
        data with weighted averages on a regular grid.More sophisti-
        cated approaches to this problem exist and should be used to
        preprocess the data outside ggnnuupplloott if this simple solution is
        found inadequate.

        See also dgrid3d.dem: dgrid3d demo.  and scatter.dem: dgrid3d
        demo.




        7788..1199..  DDuummmmyy


        The sseett dduummmmyy command changes the default dummy variable names.

        Syntax:
              set dummy {<dummy-var>} {,<dummy-var>}
              show dummy

        By default, ggnnuupplloott assumes that the independent, or "dummy",










   GNUPLOT 4.1                                                      141


        variable for the pplloott command is "t" if in parametric or polar
        mode, or "x" otherwise.  Similarly the independent variables
        for the sspplloott command are "u" and "v" in parametric mode (sspplloott
        cannot be used in polar mode), or "x" and "y" otherwise.

        It may be more convenient to call a dummy variable by a more
        physically meaningful or conventional name.  For example, when
        plotting time functions:

              set dummy t
              plot sin(t), cos(t)

        At least one dummy variable must be set on the command; sseett
        dduummmmyy by itself will generate an error message.

        Examples:
              set dummy u,v
              set dummy ,s

        The second example sets the second variable to s.



        7788..2200..  EEnnccooddiinngg


        The sseett eennccooddiinngg command selects a character encoding.  Syntax:
              set encoding {<value>}
              set encoding locale
              show encoding

        Valid values are
           default     - tells a terminal to use its default encoding
           iso_8859_1  - the most common Western European encoding used
        by many
                         Unix workstations and by MS-Windows. This
        encoding is
                         known in the PostScript world as 'ISO-Latin1'.
           iso_8859_15 - a variant of iso_8859_1 that includes the Euro
        symbol
           iso_8859_2  - used in Central and Eastern Europe
           iso_8859_9  - used in Turkey (also known as Latin5)
           koi8r       - popular Unix cyrillic encoding
           koi8u       - ukrainian Unix cyrillic encoding
           cp437       - codepage for MS-DOS
           cp850       - codepage for OS/2, Western Europe
           cp852       - codepage for OS/2, Central and Eastern Europe
           cp1250      - codepage for MS Windows, Central and Eastern
        Europe
           cp1251      - codepage for 8-bit Russian, Serbian, Bulgar-
        ian, Macedonian
           cp1254      - codepage for MS Windows, Turkish (superset of
        Latin5)










   GNUPLOT 4.1                                                      142


           utf8        - variable-length (multibyte) representation of
        Unicode
                         entry point for each character

        The command sseett eennccooddiinngg llooccaallee is different from the other
        options.  It attempts to determine the current locale from the
        runtime environment.  On most systems this is controlled by the
        environmental variables LC_ALL, LC_CTYPE, or LANG.  This mecha-
        nism is necessary, for example, to pass multibyte character
        encodings such as UTF-8 or EUC_JP to the wxt and cairopdf ter-
        minals.  This command does not affect the locale-specific rep-
        resentation of dates or numbers.  See also sseett llooccaallee and sseett
        ddeecciimmaallssiiggnn.

        Generally you must set the encoding before setting the terminal
        type.  Note that encoding is not supported by all terminal
        drivers and that the device must be able to produce the desired
        non-standard characters.



        7788..2211..  FFiitt


        The ffiitt setting defines where the ffiitt command writes its out-
        put.  If this option was built into your version of gnuplot, it
        also controls whether parameter errors from the fit will be
        written into variables.

        Syntax:
              set fit {logfile {"<filename>"}} {{no}errorvariables}
              unset fit
              show fit

        The <filename> argument must be enclosed in single or double
        quotes.

        If no filename is given or uunnsseett ffiitt is used the log file is
        reset to its default value "fit.log" or the value of the envi-
        ronmental variable FFIITT__LLOOGG.

        If the given logfile name ends with a / or \, it is interpreted
        to be a directory name, and the actual filename will be
        "fit.log" in that directory.

        If the eerrrroorrvvaarriiaabblleess option is turned on, the error of each
        fitted parameter computed by ffiitt will be copied to a user-
        defined variable whose name is formed by appending "_err" to
        the name of the parameter itself.  This is useful mainly to put
        the parameter and its error onto a plot of the data and the
        fitted function, for reference, as in:

               set fit errorvariables










   GNUPLOT 4.1                                                      143


               fit f(x) 'datafile' using 1:2 via a, b
               print "error of a is:", a_err
               set label 'a=%6.2f', a, '+/- %6.2f', a_err
               plot 'datafile' using 1:2, f(x)



        7788..2222..  FFoonnttppaatthh


        The ffoonnttppaatthh setting defines additional locations for font
        files searched when including font files. Currently only the
        postscript terminal supports ffoonnttppaatthh. If a file cannot be
        found in the current directory, the directories in ffoonnttppaatthh are
        tried. Further documentation concerning the supported file for-
        mats is included in the tteerrmmiinnaall ppoossttssccrriipptt section of the doc-
        umentation.

        Syntax:
              set fontpath {"pathlist1" {"pathlist2"...}}
              show fontpath

        Path names may be entered as single directory names, or as a
        list of path names separated by a platform-specific path sepa-
        rator, eg. colon (':') on Unix, semicolon (';') on DOS/Win-
        dows/OS/2/Amiga platforms.  The sshhooww ffoonnttppaatthh, ssaavvee and ssaavvee
        sseett commands replace the platform-specific separator with a
        space character (' ') for maximum portability. If a directory
        name ends with an exclamation mark ('!') also the subdirecto-
        ries of this directory are searched for font files.

        If the environmental variable GNUPLOT_FONTPATH is set, its con-
        tents are appended to ffoonnttppaatthh.  If it is not set, a system
        dependent default value is used. It is set by testing several
        directories for existence when using the fontpath the first
        time. Thus, the first call of sseett ffoonnttppaatthh, sshhooww ffoonnttppaatthh, ssaavvee
        ffoonnttppaatthh, pplloott, or sspplloott with embedded font files takes a lit-
        tle more time. If you want to save this time you may set the
        environmental variable GNUPLOT_FONTPATH since probing is
        switched off, then. You can find out which is the default font-
        path by using sshhooww ffoonnttppaatthh.

        However, sshhooww ffoonnttppaatthh prints the contents of user defined
        fontpath and system fontpath separately.  Also, the ssaavvee and
        ssaavvee sseett commands save only the user specified parts of ffoonntt--
        ppaatthh, for portability reasons.

        Many other terminal drivers access TrueType fonts via the gd
        library.  For these drivers the font search path is controlled
        by the environmental variable GDFONTPATH.













   GNUPLOT 4.1                                                      144


        7788..2233..  FFoorrmmaatt


        The format of the tic-mark labels can be set with the sseett ffoorr--
        mmaatt command or with the sseett ttiiccss ffoorrmmaatt or individual sseett
        {{aaxxiiss}}ttiiccss ffoorrmmaatt commands.

        Syntax:
              set format {<axes>} {"<format-string>"}
              set format {<axes>} {'<format-string>'}
              show format

        where <axes> is either xx, yy, xxyy, xx22, yy22, zz, ccbb or nothing
        (which applies the format to all axes). The following two com-
        mands are equivalent:
              set format y "%.2f"
              set ytics format "%.2f"

        The length of the string is restricted to 100 characters.  The
        default format is "% g", but other formats such as "%.2f" or
        "%3.0em" are often desirable.  The format "$%g$" is often
        desirable for LaTeX.  If no format string is given, the format
        will be returned to the default.  If the empty string "" is
        given, tics will have no labels, although the tic mark will
        still be plotted.  To eliminate the tic marks, use uunnsseett xxttiiccss
        or sseett ttiiccss ssccaallee 00.

        Newline (\n) and enhanced text markup is accepted in the format
        string.  Use double-quotes rather than single-quotes in this
        case.  See also ssyynnttaaxx.  Characters not preceded by "%" are
        printed verbatim.  Thus you can include spaces and labels in
        your format string, such as "%g m", which will put " m" after
        each number.  If you want "%" itself, double it: "%g %%".

        See also sseett xxttiiccss for more information about tic labels, and
        sseett ddeecciimmaallssiiggnn for how to use non-default decimal separators
        in numbers printed this way.  See also electron demo (elec-
        tron.dem).




             7788..2233..11..  GGpprriinnttff


             The string function gprintf("format",x) uses gnuplot's own
             format specifiers, as do the gnuplot commands sseett ffoorrmmaatt,
             sseett ttiimmeessttaammpp, and others. These format specifiers are not
             the same as those used by the standard C-language routine
             sprintf(). gprintf() accepts only a single variable to be
             formatted.  Gnuplot also provides an sprintf("for-
             mat",x1,x2,...) routine if you prefer.  For a list of gnu-
             plot's format options, see ffoorrmmaatt ssppeecciiffiieerrss.










   GNUPLOT 4.1                                                      145


             7788..2233..22..  FFoorrmmaatt ssppeecciiffiieerrss


             The acceptable formats (if not in time/date mode) are:




   +------------------------------------------------------------------+
   | Format    Explanation                                            |
   +------------------------------------------------------------------+
   |   %f      floating point notation                                |
   |%e or %E   exponential notation; an "e" or "E" before the power   |
   |%g or %G   the shorter of %e (or %E) and %f                       |
   |%x or %X   hex                                                    |
   |%o or %O   octal                                                  |
   |   %t      mantissa to base 10                                    |
   |   %l      mantissa to base of current logscale                   |
   |   %s      mantissa to base of current logscale; scientific power |
   |   %T      power to base 10                                       |
   |   %L      power to base of current logscale                      |
   |   %S      scientific power                                       |
   |   %c      character replacement for scientific power             |
   |   %P      multiple of pi                                         |
   +------------------------------------------------------------------+
   +------------------------------------------------------------------+



   A 'scientific' power is one such that the exponent is a multiple of
   three.  Character replacement of scientific powers (""%%cc"") has been
   implemented for powers in the range -18 to +18.  For numbers outside
   of this range the format reverts to exponential.

   Other acceptable modifiers (which come after the "%" but before the
   format specifier) are "-", which left-justifies the number; "+",
   which forces all numbers to be explicitly signed; " " (a space),
   which makes positive numbers have a space in front of them where
   negative numbers have "-"; "#", which places a decimal point after
   floats that have only zeroes following the decimal point; a positive
   integer, which defines the field width; "0" (the digit, not the let-
   ter) immediately preceding the field width, which indicates that
   leading zeroes are to be used instead of leading blanks; and a deci-
   mal point followed by a non-negative integer, which defines the pre-
   cision (the minimum number of digits of an integer, or the number of
   digits following the decimal point of a float).

   Some systems may not support all of these modifiers but may also
   support others; in case of doubt, check the appropriate documenta-
   tion and then experiment.

   Examples:
         set format y "%t"; set ytics (5,10)          # "5.0" and "1.0"










   GNUPLOT 4.1                                                      146


         set format y "%s"; set ytics (500,1000)      # "500" and "1.0"
         set format y "%+-12.3f"; set ytics(12345)    # "+12345.000  "
         set format y "%.2t*10^%+03T"; set ytic(12345)# "1.23*10^+04"
         set format y "%s*10^{%S}"; set ytic(12345)   # "12.345*10^{3}"
         set format y "%s %cg"; set ytic(12345)       # "12.345 kg"
         set format y "%.0P pi"; set ytic(6.283185)   # "2 pi"
         set format y "%.0f%%"; set ytic(50)          # "50%"

         set log y 2; set format y '%l'; set ytics (1,2,3)
         #displays "1.0", "1.0" and "1.5" (since 3 is 1.5 * 2^1)

   There are some problem cases that arise when numbers like 9.999 are
   printed with a format that requires both rounding and a power.

   If the data type for the axis is time/date, the format string must
   contain valid codes for the 'strftime' function (outside of ggnnuupplloott,
   type "man strftime").  See sseett ttiimmeeffmmtt for a list of the allowed
   input format codes.



             7788..2233..33..  TTiimmee//ddaattee ssppeecciiffiieerrss


             In time/date mode, the acceptable formats are:






































   GNUPLOT 4.1                                                      147


         +------------------------------------------------------+
         | Format    Explanation                                |
         +------------------------------------------------------+
         |   %a      abbreviated name of day of the week        |
         |   %A      full name of day of the week               |
         |%b or %h   abbreviated name of the month              |
         |   %B      full name of the month                     |
         |   %d      day of the month, 01--31                   |
         |   %D      shorthand for "%m/%d/%y" (only output)     |
         |   %F      shorthand for "%Y-%m-%d" (only output)     |
         |   %k      hour, 0--23 (one or two digits)            |
         |   %H      hour, 00--23 (always two digits)           |
         |   %l      hour, 1--12 (one or two digits)            |
         |   %I      hour, 01--12 (always two digits)           |
         |   %j      day of the year, 1--366                    |
         |   %m      month, 01--12                              |
         |   %M      minute, 0--60                              |
         |   %p      "am" or "pm"                               |
         |   %r      shorthand for "%I:%M:%S %p" (only output)  |
         |   %R      shorthand for %H:%M" (only output)         |
         |   %S      second, 0--60                              |
         |   %s      number of seconds since start of year 2000 |
         |   %T      shorthand for "%H:%M:%S" (only output)     |
         |   %U      week of the year (week starts on Sunday)   |
         |   %w      day of the week, 0--6 (Sunday = 0)         |
         |   %W      week of the year (week starts on Monday)   |
         |   %y      year, 0-99 in range 1969-2068              |
         |   %Y      year, 4-digit                              |
         +------------------------------------------------------+
         +------------------------------------------------------+



   Except for the non-numerical formats, these may be preceded by a "0"
   ("zero", not "oh") to pad the field length with leading zeroes, and
   a positive digit, to define the minimum field width (which will be
   overridden if the specified width is not large enough to contain the
   number).  There is a 24-character limit to the length of the printed
   text; longer strings will be truncated.

   Examples:

   Suppose the text is "76/12/25 23:11:11".  Then
         set format x                 # defaults to "12/25/76" \n
   "23:11"
         set format x "%A, %d %b %Y"  # "Saturday, 25 Dec 1976"
         set format x "%r %D"         # "11:11:11 pm 12/25/76"

   Suppose the text is "98/07/06 05:04:03".  Then
         set format x "%1y/%2m/%3d %01H:%02M:%03S"  # "98/ 7/  6
   5:04:003"












   GNUPLOT 4.1                                                      148


        7788..2244..  FFuunnccttiioonn ssttyyllee


        This form of the command is deprecated. Please see sseett ssttyyllee
        ffuunnccttiioonn.



        7788..2255..  FFuunnccttiioonnss


        The sshhooww ffuunnccttiioonnss command lists all user-defined functions and
        their definitions.

        Syntax:
              show functions

        For information about the definition and usage of functions in
        ggnnuupplloott, please see eexxpprreessssiioonnss.  See also splines as user
        defined functions (spline.dem) and use of functions and complex
        variables for airfoils (airfoil.dem).



        7788..2266..  GGrriidd


        The sseett ggrriidd command allows grid lines to be drawn on the plot.

        Syntax:
              set grid {{no}{m}xtics} {{no}{m}ytics} {{no}{m}ztics}
                       {{no}{m}x2tics} {{no}{m}y2tics}
                       {{no}{m}cbtics}
                       {polar {<angle>}}
                       {layerdefault | front | back}
                       { {linestyle <major_linestyle>}
                         | {linetype | lt <major_linetype>}
                           {linewidth | lw <major_linewidth>}
                         { , {linestyle | ls <minor_linestyle>}
                             | {linetype | lt <minor_linetype>}
                               {linewidth | lw <minor_linewidth>} } }
              unset grid
              show grid

        The grid can be enabled and disabled for the major and/or minor
        tic marks on any axis, and the linetype and linewidth can be
        specified for major and minor grid lines, also via a predefined
        linestyle, as far as the active terminal driver supports this.

        Additionally, a polar grid can be selected for 2D plots---cir-
        cles are drawn to intersect the selected tics, and radial lines
        are drawn at definable intervals.  (The interval is given in
        degrees or radians, depending on the sseett aanngglleess setting.)  Note










   GNUPLOT 4.1                                                      149


        that a polar grid is no longer automatically generated in polar
        mode.

        The pertinent tics must be enabled before sseett ggrriidd can draw
        them; ggnnuupplloott will quietly ignore instructions to draw grid
        lines at non-existent tics, but they will appear if the tics
        are subsequently enabled.

        If no linetype is specified for the minor gridlines, the same
        linetype as the major gridlines is used.  The default polar
        angle is 30 degrees.

        If ffrroonntt is given, the grid is drawn on top of the graphed
        data. If bbaacckk is given, the grid is drawn underneath the
        graphed data. Using ffrroonntt will prevent the grid from being
        obscured by dense data. The default setup, llaayyeerrddeeffaauulltt, is
        equivalent to bbaacckk for 2d plots.  In 3D plots the default is to
        split up the grid and the graph box into two layers: one
        behind, the other in front of the plotted data and functions.
        Since hhiiddddeenn33dd mode does its own sorting, it ignores all grid
        drawing order options and passes the grid lines through the
        hidden line removal machinery instead. These options actually
        affect not only the grid, but also the lines output by sseett bboorr--
        ddeerr and the various ticmarks (see sseett xxttiiccss).

        Z grid lines are drawn on the bottom of the plot.  This looks
        better if a partial box is drawn around the plot---see sseett bboorr--
        ddeerr.



        7788..2277..  HHiiddddeenn33dd


        The sseett hhiiddddeenn33dd command enables hidden line removal for sur-
        face plotting (see sspplloott).  Some optional features of the
        underlying algorithm can also be controlled using this command.

        Syntax:
              set hidden3d {defaults} |
                           { {front|back}
                             {{offset <offset>} | {nooffset}}
                             {trianglepattern <bitpattern>}
                             {{undefined <level>} | {noundefined}}
                             {{no}altdiagonal}
                             {{no}bentover} }
              unset hidden3d
              show hidden3d

        In contrast to the usual display in gnuplot, hidden line
        removal actually treats the given function or data grids as
        real surfaces that can't be seen through, so plot elements
        behind the surface will be hidden by it.  For this to work, the










   GNUPLOT 4.1                                                      150


        surface needs to have 'grid structure' (see sspplloott ddaattaaffiillee
        about this), and it has to be drawn wwiitthh lliinneess or wwiitthh lliinneess--
        ppooiinnttss.

        When hhiiddddeenn33dd is set, both the hidden portion of the surface
        and possibly its contours drawn on the base (see sseett ccoonnttoouurr)
        as well as the grid will be hidden.  Each surface has its hid-
        den parts removed with respect to itself and to other surfaces,
        if more than one surface is plotted.  Contours drawn on the
        surface (sseett ccoonnttoouurr ssuurrffaaccee) don't work.

        Labels and arrows are always visible and are unaffected.  The
        key box is never hidden by the surface. As of gnuplot version
        4.5, hidden3d also affects 3D plotting styles ppooiinnttss, llaabbeellss,
        vveeccttoorrss, and iimmppuullsseess even if no surface is present in the
        graph.  Individual plots within the graph may be explicitly
        excluded from this processing by appending the extra option
        nnoohhiiddddeenn33dd to the wwiitthh specifier.

        Hidden3d does not affect solid surfaces drawn using the pm3d
        mode. To achieve a similar effect purely for pm3d surfaces, use
        instead sseett ppmm33dd ddeepptthhoorrddeerr.  To mix pm3d surfaces with normal
        hhiiddddeenn33dd processing, use the option sseett hhiiddddeenn33dd ffrroonntt to force
        all elements included in hidden3d processing to be drawn after
        any remaining plot elements. Then draw the surface twice, once
        wwiitthh lliinneess lltt --22 and a second time wwiitthh ppmm33dd. The first
        instance will include the surface during calculation of
        occluded elements but will not draw the surface itself.

        Functions are evaluated at isoline intersections.  The algo-
        rithm interpolates linearly between function points or data
        points when determining the visible line segments.  This means
        that the appearance of a function may be different when plotted
        with hhiiddddeenn33dd than when plotted with nnoohhiiddddeenn33dd because in the
        latter case functions are evaluated at each sample.  Please see
        sseett ssaammpplleess and sseett iissoossaammpplleess for discussion of the differ-
        ence.

        The algorithm used to remove the hidden parts of the surfaces
        has some additional features controllable by this command.
        Specifying ddeeffaauullttss will set them all to their default set-
        tings, as detailed below.  If ddeeffaauullttss is not given, only
        explicitly specified options will be influenced: all others
        will keep their previous values, so you can turn on/off hidden
        line removal via sseett {{nnoo}}hhiiddddeenn33dd, without modifying the set of
        options you chose.

        The first option, ooffffsseett, influences the linestyle used for
        lines on the 'back' side.  Normally, they are drawn in a
        linestyle one index number higher than the one used for the
        front, to make the two sides of the surface distinguishable.
        You can specify a different line style offset to add instead of
        the default 1, by ooffffsseett <<ooffffsseett>>.  Option nnooooffffsseett stands for










   GNUPLOT 4.1                                                      151


        ooffffsseett 00, making the two sides of the surface use the same
        linestyle.

        Next comes the option ttrriiaanngglleeppaatttteerrnn <<bbiittppaatttteerrnn>>.  <bitpat-
        tern> must be a number between 0 and 7, interpreted as a bit
        pattern.  Each bit determines the visibility of one edge of the
        triangles each surface is split up into.  Bit 0 is for the
        'horizontal' edges of the grid, Bit 1 for the 'vertical' ones,
        and Bit 2 for the diagonals that split each cell of the origi-
        nal grid into two triangles.  The default pattern is 3, making
        all horizontal and vertical lines visible, but not the diago-
        nals.  You may want to choose 7 to see those diagonals as well.

        The uunnddeeffiinneedd <<lleevveell>> option lets you decide what the algorithm
        is to do with data points that are undefined (missing data, or
        undefined function values), or exceed the given x-, y- or z-
        ranges.  Such points can either be plotted nevertheless, or
        taken out of the input data set.  All surface elements touching
        a point that is taken out will be taken out as well, thus cre-
        ating a hole in the surface.  If <level> = 3, equivalent to
        option nnoouunnddeeffiinneedd, no points will be thrown away at all.  This
        may produce all kinds of problems elsewhere, so you should
        avoid this.  <level> = 2 will throw away undefined points, but
        keep the out-of-range ones.  <level> = 1, the default, will get
        rid of out-of-range points as well.

        By specifying nnooaallttddiiaaggoonnaall, you can override the default han-
        dling of a special case can occur if uunnddeeffiinneedd is active (i.e.
        <level> is not 3).  Each cell of the grid-structured input sur-
        face will be divided in two triangles along one of its diago-
        nals.  Normally, all these diagonals have the same orientation
        relative to the grid.  If exactly one of the four cell corners
        is excluded by the uunnddeeffiinneedd handler, and this is on the usual
        diagonal, both triangles will be excluded.  However if the
        default setting of aallttddiiaaggoonnaall is active, the other diagonal
        will be chosen for this cell instead, minimizing the size of
        the hole in the surface.

        The bbeennttoovveerr option controls what happens to another special
        case, this time in conjunction with the ttrriiaanngglleeppaatttteerrnn.  For
        rather crumply surfaces, it can happen that the two triangles a
        surface cell is divided into are seen from opposite sides (i.e.
        the original quadrangle is 'bent over'), as illustrated in the
        following ASCII art:

                                                                      C----B
            original quadrangle:  A--B      displayed quadrangle:
        |\   |
              ("set view 0,0")    | /|    ("set view 75,75" perhaps)  |
        \  |
                                  |/ |                                |
        \ |
                                  C--D                                |










   GNUPLOT 4.1                                                      152


        \|
                                                                      A
        D

        If the diagonal edges of the surface cells aren't generally
        made visible by bit 2 of the <bitpattern> there, the edge CB
        above wouldn't be drawn at all, normally, making the resulting
        display hard to understand.  Therefore, the default option of
        bbeennttoovveerr will turn it visible in this case.  If you don't want
        that, you may choose nnoobbeennttoovveerr instead.  See also hidden line
        removal demo (hidden.dem) and complex hidden line demo (sin-
        gulr.dem).



        7788..2288..  HHiissttoorryyssiizzee


        Note: the command sseett hhiissttoorryyssiizzee is only available when gnu-
        plot has been configured with the GNU readline.

        Syntax:
              set historysize <int>
              unset historysize

        When leaving gnuplot, the value of historysize is used for
        truncating the history to at most that much lines. The default
        is 500.  uunnsseett hhiissttoorryyssiizzee will disable history truncation and
        thus allow an infinite number of lines to be written to the
        history file.



        7788..2299..  IIssoossaammpplleess


        The isoline density (grid) for plotting functions as surfaces
        may be changed by the sseett iissoossaammpplleess command.

        Syntax:
              set isosamples <iso_1> {,<iso_2>}
              show isosamples

        Each function surface plot will have <iso_1> iso-u lines and
        <iso_2> iso-v lines.  If you only specify <iso_1>, <iso_2> will
        be set to the same value as <iso_1>.  By default, sampling is
        set to 10 isolines per u or v axis.  A higher sampling rate
        will produce more accurate plots, but will take longer.  These
        parameters have no effect on data file plotting.

        An isoline is a curve parameterized by one of the surface
        parameters while the other surface parameter is fixed.  Iso-
        lines provide a simple means to display a surface.  By fixing










   GNUPLOT 4.1                                                      153


        the u parameter of surface s(u,v), the iso-u lines of the form
        c(v) = s(u0,v) are produced, and by fixing the v parameter, the
        iso-v lines of the form c(u) = s(u,v0) are produced.

        When a function surface plot is being done without the removal
        of hidden lines, sseett ssaammpplleess  controls the number of points
        sampled along each isoline;  see sseett ssaammpplleess and sseett hhiiddddeenn33dd.
        The contour algorithm assumes that a function sample occurs at
        each isoline intersection, so change in ssaammpplleess as well as
        iissoossaammpplleess may be desired when changing the resolution of a
        function surface/contour.



        7788..3300..  KKeeyy


        The sseett kkeeyy command enables a key (or legend) describing plots
        on a plot.

        The contents of the key, i.e., the names given to each plotted
        data set and function and samples of the lines and/or symbols
        used to represent them, are determined by the ttiittllee and wwiitthh
        options of the {ss}pplloott command.  Please see pplloott ttiittllee and pplloott
        wwiitthh for more information.

        Syntax:
              set key {on|off} {default}
                      {{inside | outside} | {lmargin | rmargin | tmar-
        gin | bmargin}
                        | {at <position>}}
                      {left | right | center} {top | bottom | center}
                      {vertical | horizontal} {Left | Right}
                      {{no}reverse} {{no}invert}
                      {samplen <sample_length>} {spacing <verti-
        cal_spacing>}
                      {width <width_increment>}
                      {height <height_increment>}
                      {{no}autotitle {columnheader}}
                      {title "<text>"} {{no}enhanced}
                      {font "<face>,<size>"} {textcolor <colorspec>}
                      {{no}box { {linestyle | ls <line_style>}
                                 | {linetype | lt <line_type>}
                                   {linewidth | lw <line_width>}}}
                      {maxcols {<max no. of columns> | auto}}
                      {maxrows {<max no. of rows> | auto}}
              unset key
              show key

        The key contains a title and a sample (line, point, box) for
        each plot in the graph. The key may be turned off by requesting
        sseett kkeeyy ooffff or uunnsseett kkeeyy.  Individual key entries may be turned
        off by using the nnoottiittllee keyword in the corresponding plot










   GNUPLOT 4.1                                                      154


        command.

        Elements within the key are stacked according to vveerrttiiccaall or
        hhoorriizzoonnttaall.  In the case of vveerrttiiccaall, the key occupies as few
        columns as possible.  That is, elements are aligned in a column
        until running out of vertical space at which point a new column
        is started.  The vertical space may be limited using 'maxrows'.
        In the case of hhoorriizzoonnttaall, the key occupies as few rows as pos-
        sible.  The horizontal space may be limited using 'maxcols'.

        By default the key is placed in the upper right inside corner
        of the graph.  The keywords lleefftt, rriigghhtt, ttoopp, bboottttoomm, cceenntteerr,
        iinnssiiddee, oouuttssiiddee, llmmaarrggiinn, rrmmaarrggiinn, ttmmaarrggiinn, bbmmaarrggiinn (, aabboovvee,
        oovveerr, bbeellooww and uunnddeerr) may be used to automatically place the
        key in other positions of the graph.  Also an aatt <<ppoossiittiioonn>> may
        be given to indicate precisely where the plot should be placed.
        In this case, the keywords lleefftt, rriigghhtt, ttoopp, bboottttoomm and cceenntteerr
        serve an analogous purpose for alignment.  For more informa-
        tion, see kkeeyy ppllaacceemmeenntt.

        Justification of the plot titles within the key is controlled
        by LLeefftt or RRiigghhtt (default).  The text and sample can be
        reversed (rreevveerrssee) and a box can be drawn around the key (bbooxx
        {{......}}) in a specified lliinneettyyppee and lliinneewwiiddtthh, or a user-defined
        lliinneessttyyllee.

        By default the first plot label is at the top of the key and
        successive labels are entered below it. The iinnvveerrtt option
        causes the first label to be placed at the bottom of the key,
        with successive labels entered above it. This option is useful
        to force the vertical ordering of labels in the key to match
        the order of box types in a stacked histogram.

        The <height_increment> is a number of character heights to be
        added to or subtracted from the height of the key box.  This is
        useful mainly when you are putting a box around the key and
        want larger borders around the key entries.

        All plotted curves of ppllootts and ssppllootts are titled according to
        the default option aauuttoottiittlleess. The automatic generation of
        titles can be suppressed by nnooaauuttoottiittlleess; then only those
        titles explicitly defined by ((ss))pplloott ...... ttiittllee ...... will be
        drawn.

        The command sseett kkeeyy aauuttoottiittllee ccoolluummnnhheeaaddeerr causes the first
        entry in each column of input data to be interpreted as a text
        string and used as a title for the corresponding plot. If the
        quantity being plotted is a function of data from several col-
        umns, gnuplot may be confused as to which column to draw the
        title from. In this case it is necessary to specify the column
        explicitly in the plot command, e.g.

              plot "datafile" using (($2+$3)/$4) title columnhead(3)










   GNUPLOT 4.1                                                      155


        with lines

        An overall title can be put on the key (ttiittllee ""<<tteexxtt>>"")---see
        also ssyynnttaaxx for the distinction between text in single- or dou-
        ble-quotes.  The key title uses the same justification as do
        the plot titles.

        The defaults for sseett kkeeyy are oonn, rriigghhtt, ttoopp, vveerrttiiccaall, RRiigghhtt,
        nnoorreevveerrssee, nnooiinnvveerrtt, ssaammpplleenn 44, ssppaacciinngg 11..2255, ttiittllee """", and
        nnoobbooxx.  The default <linetype> is the same as that used for the
        plot borders.  Entering sseett kkeeyy ddeeffaauulltt returns the key to its
        default configuration.

        The key is drawn as a sequence of lines, with one plot
        described on each line.  On the right-hand side (or the left-
        hand side, if rreevveerrssee is selected) of each line is a represen-
        tation that attempts to mimic the way the curve is plotted.  On
        the other side of each line is the text description (the line
        title), obtained from the pplloott command.  The lines are verti-
        cally arranged so that an imaginary straight line divides the
        left- and right-hand sides of the key.  It is the coordinates
        of the top of this line that are specified with the sseett kkeeyy
        command.  In a pplloott, only the x and y coordinates are used to
        specify the line position.  For a sspplloott, x, y and z are all
        used as a 3D location mapped using the same mapping as the
        graph itself to form the required 2D screen position of the
        imaginary line.

        When using the TeX or PostScript drivers, or similar drivers
        where formatting information is embedded in the string, ggnnuupplloott
        is unable to calculate correctly the width of the string for
        key positioning.  If the key is to be positioned at the left,
        it may be convenient to use the combination  sseett kkeeyy lleefftt LLeefftt
        rreevveerrssee.  The box and gap in the grid will be the width of the
        literal string.

        If sspplloott is being used to draw contours, the contour labels
        will be listed in the key.  If the alignment of these labels is
        poor or a different number of decimal places is desired, the
        label format can be specified.  See sseett ccllaabbeell for details.

        Examples:

        This places the key at the default location:
              set key default

        This disables the key:
              unset key

        This places a key at coordinates 2,3.5,2 in the default (first)
        coordinate system:
              set key at 2,3.5,2











   GNUPLOT 4.1                                                      156


        This places the key below the graph:
              set key below

        This places the key in the bottom left corner, left-justifies
        the text, gives it a title, and draws a box around it in line-
        type 3:
              set key left bottom Left title 'Legend' box 3




             7788..3300..11..  KKeeyy ppllaacceemmeenntt


             To understand positioning, the best concept is to think of
             a region, i.e., inside/outside, or one of the margins.
             Along with the region, keywords lleefftt//cceenntteerr//rriigghhtt (l/c/r)
             and ttoopp//cceenntteerr//bboottttoomm (t/c/b) control where within the
             particular region the key should be placed.

             When in iinnssiiddee mode, the keywords lleefftt (l), rriigghhtt (r), ttoopp
             (t), bboottttoomm (b), and cceenntteerr (c) push the key out toward
             the plot boundary as illustrated:

                  t/l   t/c   t/r

                  c/l    c    c/r

                  b/l   b/c   b/r


             When in oouuttssiiddee mode, automatic placement is similar to
             the above illustration, but with respect to the view,
             rather than the graph boundary.  That is, a border is
             moved inward to make room for the key outside of the plot-
             ting area, although this may interfere with other labels
             and may cause an error on some devices.  The particular
             plot border that is moved depends upon the position
             described above and the stacking direction.  For options
             centered in one of the dimensions, there is no ambiguity
             about which border to move.  For the corners, when the
             stack direction is vveerrttiiccaall, the left or right border is
             moved inward appropriately.  When the stack direction is
             hhoorriizzoonnttaall, the top or bottom border is moved inward
             appropriately.

             The margin syntax allows automatic placement of key
             regardless of stack direction.  When one of the margins
             llmmaarrggiinn (lm), rrmmaarrggiinn (rm), ttmmaarrggiinn (tm), and bbmmaarrggiinn (bm)
             is combined with a single, non-conflicting direction key-
             word, the following illustrated positions may contain the
             key:











   GNUPLOT 4.1                                                      157


                       l/tm  c/tm  r/tm

                  t/lm                  t/rm

                  c/lm                  c/rm

                  b/lm                  b/rm

                       l/bm  c/bm  r/bm


             Keywords aabboovvee and oovveerr are synonymous with ttmmaarrggiinn.  For
             version compatibility, aabboovvee or oovveerr without an additional
             l/c/r or stack direction keyword uses cceenntteerr and hhoorriizzoonn--
             ttaall.  Keywords bbeellooww and uunnddeerr are synonymous with bbmmaarr--
             ggiinn.  For compatibility, bbeellooww or uunnddeerr without an addi-
             tional l/c/r or stack  direction keyword uses cceenntteerr and
             hhoorriizzoonnttaall.  A further compatibility issue is that oouuttssiiddee
             appearing without an additional t/b/c or stack direction
             keyword uses ttoopp, rriigghhtt and vveerrttiiccaall (i.e., the same as
             t/rm above).

             The <position> can be a simple x,y,z as in previous ver-
             sions, but these can be preceded by one of five keywords
             (ffiirrsstt, sseeccoonndd, ggrraapphh, ssccrreeeenn, cchhaarraacctteerr) which selects
             the coordinate system in which the position of the first
             sample line is specified.  See ccoooorrddiinnaatteess for more
             details.  The effect of lleefftt, rriigghhtt, ttoopp, bboottttoomm, and cceenn--
             tteerr when <position> is given is to align the key as though
             it were text positioned using the label command, i.e.,
             lleefftt means left align with key to the right of <position>,
             etc.



             7788..3300..22..  KKeeyy ssaammpplleess


             By default, each plot on the graph generates a correspond-
             ing entry in the key.  This entry contains a plot title
             and a sample line/point/box of the same color and fill
             properties as used in the plot itself.  The font and text-
             color properties control the appearance of the individual
             plot titles that appear in the key. Setting the textcolor
             to "rgb variable" causes the text for each key entry to be
             the same color as the line or fill color for that plot.
             This was the default in some earlier versions of gnuplot.

             The length of the sample line can be controlled by ssaamm--
             pplleenn.  The sample length is computed as the sum of the tic
             length and <sample_length> times the character width.
             ssaammpplleenn also affects the positions of point samples in the
             key since these are drawn at the midpoint of the sample










   GNUPLOT 4.1                                                      158


             line, even if the sample line itself is not drawn.

             The vertical spacing between lines is controlled by ssppaacc--
             iinngg.  The spacing is set equal to the product of the
             pointsize, the vertical tic size, and <vertical_spacing>.
             The program will guarantee that the vertical spacing is no
             smaller than the character height.

             The <width_increment> is a number of character widths to
             be added to or subtracted from the length of the string.
             This is useful only when you are putting a box around the
             key and you are using control characters in the text.
             ggnnuupplloott simply counts the number of characters in the
             string when computing the box width; this allows you to
             correct it.



        7788..3311..  LLaabbeell


        Arbitrary labels can be placed on the plot using the sseett llaabbeell
        command.

        Syntax:
              set label {<tag>} {"<label text>"} {at <position>}
                        {left | center | right}
                        {norotate | rotate {by <degrees>}}
                        {font "<name>{,<size>}"}
                        {noenhanced}
                        {front | back}
                        {textcolor <colorspec>}
                        {point <pointstyle> | nopoint}
                        {offset <offset>}
              unset label {<tag>}
              show label

        The <position> is specified by either x,y or x,y,z, and may be
        preceded by ffiirrsstt, sseeccoonndd, ggrraapphh, ssccrreeeenn, or cchhaarraacctteerr to
        select the coordinate system.  See ccoooorrddiinnaatteess for details.

        The tag is an integer that is used to identify the label. If no
        <tag> is given, the lowest unused tag value is assigned auto-
        matically.  The tag can be used to delete or modify a specific
        label.  To change any attribute of an existing label, use the
        sseett llaabbeell command with the appropriate tag, and specify the
        parts of the label to be changed.

        The <label text> can be a string constant, a string variable,
        or a string- valued expression. See ssttrriinnggss, sspprriinnttff, and
        ggpprriinnttff.

        By default, the text is placed flush left against the point










   GNUPLOT 4.1                                                      159


        x,y,z.  To adjust the way the label is positioned with respect
        to the point x,y,z, add the justification parameter, which may
        be lleefftt, rriigghhtt or cceenntteerr, indicating that the point is to be at
        the left, right or center of the text.  Labels outside the
        plotted boundaries are permitted but may interfere with axis
        labels or other text.

        If rroottaattee is given, the label is written vertically (if the
        terminal can do so, of course).  If rroottaattee bbyy <<ddeeggrreeeess>> is
        given, conforming terminals will try to write the text at the
        specified angle; non-conforming terminals will treat this as
        vertical text.

        Font and its size can be chosen explicitly by ffoonntt
        ""<<nnaammee>>{{,,<<ssiizzee>>}}"" if the terminal supports font settings.  Oth-
        erwise the default font of the terminal will be used.

        Normally the enhanced text mode string interpretation, if
        enabled for the current terminal, is applied to all text
        strings including label text.  The nnooeennhhaanncceedd property can be
        used to exempt a specific label from the enhanced text mode
        processing.  The can be useful if the label contains under-
        scores, for example. See eennhhaanncceedd tteexxtt.

        If ffrroonntt is given, the label is written on top of the graphed
        data. If bbaacckk is given (the default), the label is written
        underneath the graphed data.  Using ffrroonntt will prevent a label
        from being obscured by dense data.

        tteexxttccoolloorr <<ccoolloorrssppeecc>> changes the color of the label text.
        <colorspec> can be a linetype, an rgb color, or a palette map-
        ping. See help for ccoolloorrssppeecc and ppaalleettttee.  tteexxttccoolloorr may be
        abbreviated ttcc.
           `tc default` resets the text color to its default state.
           `tc lt <n>` sets the text color to that of line type <n>.
           `tc ls <n>` sets the text color to that of line style <n>.
           `tc palette z` selects a palette color corresponding to the
        label z position.
           `tc palette cb <val>` selects a color corresponding to <val>
        on the colorbar.
           `tc palette fraction <val>`, with 0<=val<=1, selects a color
        corresponding to
               the mapping [0:1] to grays/colors of the `palette`.
           `tc rgb "#RRGGBB"` selects an arbitrary 24-bit RGB color.

        If a <pointstyle> is given, using keywords lltt, pptt and ppss, see
        ssttyyllee, a point with the given style and color of the given line
        type is plotted at the label position and the text of the label
        is displaced slightly.  This option is used by default for
        placing labels in mmoouussee enhanced terminals.  Use nnooppooiinntt to
        turn off the drawing of a point near the label (this is the
        default).











   GNUPLOT 4.1                                                      160


        The displacement defaults to 1,1 in ppooiinnttssiizzee units if a
        <pointstyle> is given, 0,0 if no <pointstyle> is given.  The
        displacement can be controlled by the optional ooffffsseett <<ooffffsseett>>
        where <offset> is specified by either x,y or x,y,z, and may be
        preceded by ffiirrsstt, sseeccoonndd, ggrraapphh, ssccrreeeenn, or cchhaarraacctteerr to
        select the coordinate system.  See ccoooorrddiinnaatteess for details.

        If one (or more) axis is timeseries, the appropriate coordinate
        should be given as a quoted time string according to the
        ttiimmeeffmmtt format string.  See sseett xxddaattaa and sseett ttiimmeeffmmtt.

        The EEPIC, Imagen, LaTeX, and TPIC drivers allow \\ in a string
        to specify a newline.

        Label coordinates and text can also be read from a data file
        (see llaabbeellss).

        Examples:

        To set a label at (1,2) to "y=x", use:
              set label "y=x" at 1,2

        To set a Sigma of size 24, from the Symbol font set, at the
        center of the graph, use:
              set label "S" at graph 0.5,0.5 center font "Symbol,24"

        To set a label "y=x^2" with the right of the text at (2,3,4),
        and tag the label as number 3, use:
              set label 3 "y=x^2" at 2,3,4 right

        To change the preceding label to center justification, use:
              set label 3 center

        To delete label number 2, use:
              unset label 2

        To delete all labels, use:
              unset label

        To show all labels (in tag order), use:
              show label

        To set a label on a graph with a timeseries on the x axis, use,
        for example:
              set timefmt "%d/%m/%y,%H:%M"
              set label "Harvest" at "25/8/93",1

        To display a freshly fitted parameter on the plot with the data
        and the fitted function, do this after the ffiitt, but before the
        pplloott:
              set label sprintf("a = %3.5g",par_a) at 30,15
              bfit = gprintf("b = %s*10^%S",par_b)
              set label bfit at 30,20










   GNUPLOT 4.1                                                      161


        To display a function definition along with its fitted parame-
        ters, use:
              f(x)=a+b*x
              fit f(x) 'datafile' via a,b
              set label GPFUN_f at graph .05,.95
              set label sprintf("a = %g", a) at graph .05,.90
              set label sprintf("b = %g", b) at graph .05,.85

        To set a label displaced a little bit from a small point:
              set label 'origin' at 0,0 point lt 1 pt 2 ps 3 offset
        1,-1

        To set a label whose color matches the z value (in this case
        5.5) of some point on a 3D splot colored using pm3d:
              set label 'text' at 0,0,5.5 tc palette z




        7788..3322..  LLmmaarrggiinn


        The command sseett llmmaarrggiinn sets the size of the left margin.
        Please see sseett mmaarrggiinn for details.



        7788..3333..  LLooaaddppaatthh


        The llooaaddppaatthh setting defines additional locations for data and
        command files searched by the ccaallll, llooaadd, pplloott and sspplloott com-
        mands.  If a file cannot be found in the current directory, the
        directories in llooaaddppaatthh are tried.

        Syntax:
              set loadpath {"pathlist1" {"pathlist2"...}}
              show loadpath

        Path names may be entered as single directory names, or as a
        list of path names separated by a platform-specific path sepa-
        rator, eg. colon (':') on Unix, semicolon (';') on DOS/Win-
        dows/OS/2/Amiga platforms.  The sshhooww llooaaddppaatthh, ssaavvee and ssaavvee
        sseett commands replace the platform-specific separator with a
        space character (' ') for maximum portability.

        If the environment variable GNUPLOT_LIB is set, its contents
        are appended to llooaaddppaatthh.  However, sshhooww llooaaddppaatthh prints the
        contents of user defined loadpath and system loadpath sepa-
        rately.  Also, the ssaavvee and ssaavvee sseett commands save only the
        user specified parts of llooaaddppaatthh, for portability reasons.












   GNUPLOT 4.1                                                      162


        7788..3344..  LLooccaallee


        The llooccaallee setting determines the language with which
        {{xx,,yy,,zz}}{{dd,,mm}}ttiiccss will write the days and months.

        Syntax:
              set locale {"<locale>"}

        <locale> may be any language designation acceptable to your
        installation.  See your system documentation for the available
        options.  The command sseett llooccaallee """" will try to determine the
        locale from the LC_TIME, LC_ALL, or LANG environment variables.

        To change the decimal point locale, see sseett ddeecciimmaallssiiggnn.  To
        change the character encoding to the current locale, see sseett
        eennccooddiinngg.



        7788..3355..  LLooggssccaallee


        Syntax:
              set logscale <axes> <base>
              unset logscale <axes>
              show logscale

        where <axes> may be any combinations of xx, xx22, yy, yy22, zz, and ccbb
        in any order, and where <base> is the base of the log scaling.
        If <base> is not given, then 10 is assumed.  If <axes> is not
        given, then all axes are assumed.  The command uunnsseett llooggssccaallee
        turns off log scaling for the specified axes.

        Examples:

        To enable log scaling in both x and z axes:
              set logscale xz

        To enable scaling log base 2 of the y axis:
              set logscale y 2

        To enable z and color log axes for a pm3d plot:
              set logscale zcb

        To disable z axis log scaling:
              unset logscale z
















   GNUPLOT 4.1                                                      163


        7788..3366..  MMaaccrrooss


        If command line macro substitution is enabled, then tokens in
        the command line of the form @<stringvariablename> will be
        replaced by the text string contained in <stringvariablename>.
        See ssuubbssttiittuuttiioonn.

        Syntax:
             set macros




        7788..3377..  MMaappppiinngg


        If data are provided to sspplloott in spherical or cylindrical coor-
        dinates, the sseett mmaappppiinngg command should be used to instruct
        ggnnuupplloott how to interpret them.

        Syntax:
              set mapping {cartesian | spherical | cylindrical}

        A cartesian coordinate system is used by default.

        For a spherical coordinate system, the data occupy two or three
        columns (or uussiinngg entries).  The first two are interpreted as
        the azimuthal and polar angles theta and phi (or "longitude"
        and "latitude"), in the units specified by sseett aanngglleess.  The
        radius r is taken from the third column if there is one, or is
        set to unity if there is no third column.  The mapping is:

              x = r * cos(theta) * cos(phi)
              y = r * sin(theta) * cos(phi)
              z = r * sin(phi)

        Note that this is a "geographic" spherical system, rather than
        a "polar" one (that is, phi is measured from the equator,
        rather than the pole).

        For a cylindrical coordinate system, the data again occupy two
        or three columns.  The first two are interpreted as theta (in
        the units specified by sseett aanngglleess) and z.  The radius is either
        taken from the third column or set to unity, as in the spheri-
        cal case.  The mapping is:

              x = r * cos(theta)
              y = r * sin(theta)
              z = z

        The effects of mmaappppiinngg can be duplicated with the uussiinngg filter
        on the sspplloott command, but mmaappppiinngg may be more convenient if










   GNUPLOT 4.1                                                      164


        many data files are to be processed.  However even if mmaappppiinngg
        is used, uussiinngg may still be necessary if the data in the file
        are not in the required order.

        mmaappppiinngg has no effect on pplloott.  world.dem: mapping demos.



        7788..3388..  MMaarrggiinn


        The computed margins can be overridden by the sseett mmaarrggiinn com-
        mands.  sshhooww mmaarrggiinn shows the current settings.

        Syntax:
              set bmargin {{at screen} <margin>}
              set lmargin {{at screen} <margin>}
              set rmargin {{at screen} <margin>}
              set tmargin {{at screen} <margin>}
              show margin

        The default units of <margin> are character heights or widths,
        as appropriate.  A positive value defines the absolute size of
        the margin.  A negative value (or none) causes ggnnuupplloott to
        revert to the computed value.  For 3D plots, only the left mar-
        gin can be set using character units.

        The keywords aatt ssccrreeeenn indicates that the margin is specified
        as a fraction of the full drawing area. This can be used to
        precisely line up the corners of individual 2D and 3D graphs in
        a multiplot. This placement ignores the current values of sseett
        oorriiggiinn and sseett ssiizzee, and is intended as an alternative method
        for positioning graphs within a multiplot.

        Normally the margins of a plot are automatically calculated
        based on tics, tic labels, axis labels, the plot title, the
        timestamp and the size of the key if it is outside the borders.
        If, however, tics are attached to the axes (sseett xxttiiccss aaxxiiss, for
        example), neither the tics themselves nor their labels will be
        included in either the margin calculation or the calculation of
        the positions of other text to be written in the margin.  This
        can lead to tic labels overwriting other text if the axis is
        very close to the border.



        7788..3399..  MMoouussee


        The command sseett mmoouussee enables mouse actions. Currently the pm,
        x11, ggi, windows and wxt terminals are mouse enhanced. There
        are two mouse modes. The 2d-graph mode works for 2d graphs and
        for maps (i.e. splots with sseett vviieeww having z-rotation 0, 90,










   GNUPLOT 4.1                                                      165


        180, 270 or 360 degrees, including sseett vviieeww mmaapp) and it allows
        tracing the position over graph, zooming, annotating graph etc.
        For 3d graphs sspplloott, the view and scaling of the graph can be
        changed with mouse buttons 1 and 2. If additionally to these
        buttons the modifier <ctrl> is hold down, the coordinate system
        only is rotated which is useful for large data sets. A vertical
        motion of Button 2 with the shift key hold down changes the
        xxyyppllaannee.

        Mousing is not available in multiplot mode. When multiplot is
        finished using uunnsseett mmuullttiipplloott, then the mouse will be turned
        on again and acts on the last plot (like replot does).

        Syntax:
              set mouse {doubleclick <ms>} {nodoubleclick} \
                        {{no}zoomcoordinates} \
                        {noruler | ruler {at x,y}} \
                        {polardistance{deg|tan} | nopolardistance} \
                        {format <string>} \
                        {clipboardformat <int>/<string>} \
                        {mouseformat <int>/<string>} \
                        {{no}labels {"labeloptions"}} \
                        {{no}zoomjump} {{no}verbose}
              unset mouse

        The doubleclick resolution is given in milliseconds and used
        for Button 1 which copies the current mouse position to the
        cclliippbbooaarrdd. If you want that to be done by single clicking a
        value of 0 ms can be used. The default value is 300 ms.

        The option zzoooommccoooorrddiinnaatteess determines if the coordinates of the
        zoom box are drawn at the edges while zooming. This is on by
        default.

        The options nnoorruulleerr and rruulleerr switch the ruler off and on, the
        latter optionally setting the origin at the given coordinates.
        While the ruler is on, the distance in user units from the
        ruler origin to the mouse is displayed continuously. By
        default, toggling the ruler has the key binding 'r'.

        The option ppoollaarrddiissttaannccee determines if the distance between the
        mouse cursor and the ruler is also shown in polar coordinates
        (distance and angle in degrees or tangent (slope)). This corre-
        sponds to the default key binding '5'.

        The ffoorrmmaatt option takes a fprintf like format string which
        determines how floating point numbers are printed to the driv-
        ers window and the clipboard.  The default is "% #g".

        cclliippbbooaarrddffoorrmmaatt and mmoouusseeffoorrmmaatt are used for formatting the
        text on Button1 and Button2 actions -- copying the coordinates
        to the clipboard and temporarily annotating the mouse position.
        This corresponds to the key bindings '1', '2', '3', '4' (see










   GNUPLOT 4.1                                                      166


        the driver's documentation). If the argument is a string this
        string is used as c format specifier and should contain two
        float specifiers, e.g. sseett mmoouussee mmoouusseeffoorrmmaatt ""mmoouussee == %%55..22gg,,
        %%1100..22ff"". Use sseett mmoouussee mmoouusseeffoorrmmaatt """" to turn this string off
        again.

        The following formats are available (format 6 may only be
        selected if the format string was specified already):

         0   real coordinates in  brackets e.g. [1.23, 2.45]
         1   real coordinates w/o brackets e.g.  1.23, 2.45
         2   x == timefmt                       [(as set by `set
        timefmt`), 2.45]
         3   x == date                          [31. 12. 1999, 2.45]
         4   x == time                          [23:59, 2.45]
         5   x == date / time                   [31. 12. 1999 23:59,
        2.45]
         6   alt. format, specified as string   ""

        Choose the option llaabbeellss to define persistent gnuplot labels
        using Button 2.  The default is nnoollaabbeellss, which makes Button 2
        draw only a temporary label at the mouse position. Labels are
        drawn with the current setting of mmoouusseeffoorrmmaatt.  The llaabbeelloopp--
        ttiioonnss string is passed to the sseett llaabbeell command.  The default
        is "point pointstyle 1" which will plot a small plus at the
        label position.  Temporary labels will disappear at the next
        rreepplloott or mouse zoom operation.  Persistent labels can be
        removed by holding the Ctrl-Key down while clicking Button 2 on
        the label's point. The threshold for how close you must be to
        the label is also determined by the ppooiinnttssiizzee.

        If the option zzoooommjjuummpp is on, the mouse pointer will be auto-
        matically offset a small distance after starting a zoom region
        with button 3. This can be useful to avoid a tiny (or even
        empty) zoom region. zzoooommjjuummpp is off by default.

        If the option vveerrbboossee is turned on the communication commands
        are shown during execution. This option can also be toggled by
        hitting 66 in the driver's window. vveerrbboossee is off by default.

        Press 'h' in the driver's window for a short summary of the
        mouse and key bindings.  This will also display user defined
        bindings or hhoottkkeeyyss which can be defined using the bbiinndd com-
        mand, see help for bbiinndd.  Note, that user defined hhoottkkeeyyss may
        override the default bindings.

        Press 'q' in the driver's window to close the window. This key
        cannot be overridden with the bbiinndd command.

        See also help for bbiinndd and llaabbeell.













   GNUPLOT 4.1                                                      167


             7788..3399..11..  XX1111 mmoouussee


             If multiple X11 plot windows have been opened using the
             sseett tteerrmm xx1111 <<nn>> terminal option, then only the current
             plot window supports the entire range of mouse commands
             and hotkeys.  The other windows will, however, continue to
             display mouse coordinates at the lower left.

             For consistency with other screen terminals, X11 mouse
             support is turned on by default, wherever the standard
             input comes from. However, on some UNIX flavors, special
             input devices as /dev/null might not be sseelleecctt--aabbllee; using
             such devices with the mouse turned on will hang gnuplot.
             Please turn off mousing with uunnsseett mmoouussee if you are in
             this situation.



        7788..4400..  MMuullttiipplloott


        The command sseett mmuullttiipplloott places ggnnuupplloott in the multiplot mode,
        in which several plots are placed on the same page, window, or
        screen.

        Syntax:
              set multiplot { layout <rows>,<cols>
                              {rowsfirst|columnsfirst} {down-
        wards|upwards}
                              {title <page title>}
                              {scale <xscale>{,<yscale>}} {offset
        <xoff>{,<yoff>}}
                            }
              unset multiplot

        For some terminals, no plot is displayed until the command
        uunnsseett mmuullttiipplloott is given, which causes the entire page to be
        drawn and then returns gnuplot to its normal single-plot mode.
        For other terminals, each separate pplloott command produces an
        updated display, either by redrawing all previous ones and the
        newly added plot, or by just adding the new plot to the exist-
        ing display.

        The area to be used by the next plot is not erased before doing
        the new plot.  The cclleeaarr command can be used to do this if
        wanted, as is typically the case for "inset" plots.

        Any labels or arrows that have been defined will be drawn for
        each plot according to the current size and origin (unless
        their coordinates are defined in the ssccrreeeenn system).  Just
        about everything else that can be sseett is applied to each plot,
        too.  If you want something to appear only once on the page,










   GNUPLOT 4.1                                                      168


        for instance a single time stamp, you'll need to put a sseett
        ttiimmee/uunnsseett ttiimmee pair around one of the pplloott, sspplloott or rreepplloott
        commands within the sseett mmuullttiipplloott/uunnsseett mmuullttiipplloott block.

        The multiplot title is separate from the individual plot
        titles, if any.  Space is reserved for it at the top of the
        page, spanning the full width of the canvas.

        The commands sseett oorriiggiinn and sseett ssiizzee must be used to correctly
        position each plot if no layout is specified or if fine tuning
        is desired.  See sseett oorriiggiinn and sseett ssiizzee for details of their
        usage.

        Example:
              set multiplot
              set size 0.4,0.4
              set origin 0.1,0.1
              plot sin(x)
              set size 0.2,0.2
              set origin 0.5,0.5
              plot cos(x)
              unset multiplot

        This displays a plot of cos(x) stacked above a plot of sin(x).

        sseett ssiizzee and sseett oorriiggiinn refer to the entire plotting area used
        for each plot.  Please also see sseett tteerrmm ssiizzee.  If you want to
        have the axes themselves line up, you can guarantee that the
        margins are the same size with the sseett mmaarrggiinn commands.  See
        sseett mmaarrggiinn for their use.  Note that the margin settings are
        absolute, in character units, so the appearance of the graph in
        the remaining space will depend on the screen size of the dis-
        play device, e.g., perhaps quite different on a video display
        and a printer.

        With the llaayyoouutt option you can generate simple multiplots with-
        out having to give the sseett ssiizzee and sseett oorriiggiinn commands before
        each plot:  Those are generated automatically, but can be over-
        ridden at any time.  With llaayyoouutt the display will be divided by
        a grid with <rows> rows and <cols> columns.  This grid is
        filled rows first or columns first depending on whether the
        corresponding option is given in the multiplot command.  The
        stack of plots can grow ddoowwnnwwaarrddss or uuppwwaarrddss.  Default is rroowwss--
        ffiirrsstt and ddoowwnnwwaarrddss.

        Each plot can be scaled by ssccaallee and shifted with ooffffsseett; if
        the y-values for scale or offset are omitted, the x-value will
        be used.  uunnsseett mmuullttiipplloott will turn off the automatic layout
        and restore the values of sseett ssiizzee and sseett oorriiggiinn as they were
        before sseett mmuullttiipplloott llaayyoouutt.

        Example:
              set size 1,1










   GNUPLOT 4.1                                                      169


              set origin 0,0
              set multiplot layout 3,2 columnsfirst scale 1.1,0.9
              [ up to 6 plot commands here ]
              unset multiplot

        The above example will produce 6 plots in 2 columns filled top
        to bottom, left to right.  Each plot will have a horizontal
        size of 1.1/2 and a vertical size of 0.9/3.

        See also multiplot demo (multiplt.dem)



        7788..4411..  MMxx22ttiiccss


        Minor tic marks along the x2 (top) axis are controlled by sseett
        mmxx22ttiiccss.  Please see sseett mmxxttiiccss.



        7788..4422..  MMxxttiiccss


        Minor tic marks along the x axis are controlled by sseett mmxxttiiccss.
        They can be turned off with uunnsseett mmxxttiiccss.  Similar commands
        control minor tics along the other axes.

        Syntax:
              set mxtics {<freq> | default}
              unset mxtics
              show mxtics

        The same syntax applies to mmyyttiiccss, mmzzttiiccss, mmxx22ttiiccss, mmyy22ttiiccss and
        mmccbbttiiccss.

        <freq> is the number of sub-intervals (NOT the number of minor
        tics) between major tics (the default for a linear axis is
        either two or five depending on the major tics, so there are
        one or four minor tics between major tics). Selecting ddeeffaauulltt
        will return the number of minor ticks to its default value.

        If the axis is logarithmic, the number of sub-intervals will be
        set to a reasonable number by default (based upon the length of
        a decade).  This will be overridden if <freq> is given.  How-
        ever the usual minor tics (2, 3, ..., 8, 9 between 1 and 10,
        for example) are obtained by setting <freq> to 10, even though
        there are but nine sub-intervals.

        To set minor tics at arbitrary positions, use the ("<label>"
        <pos> <level>, ...) form of sseett {{xx||xx22||yy||yy22||zz}}ttiiccss with <label>
        empty and <level> set to 1.











   GNUPLOT 4.1                                                      170


        The sseett mm{{xx||xx22||yy||yy22||zz}}ttiiccss commands work only when there are
        uniformly spaced major tics.  If all major tics were placed
        explicitly by sseett {{xx||xx22||yy||yy22||zz}}ttiiccss, then minor tic commands
        are ignored.  Implicit major tics and explicit minor tics can
        be combined using sseett {{xx||xx22||yy||yy22||zz}}ttiiccss and sseett
        {{xx||xx22||yy||yy22||zz}}ttiiccss aadddd.

        Examples:
              set xtics 0, 5, 10
              set xtics add (7.5)
              set mxtics 5
        Major tics at 0,5,7.5,10, minor tics at 1,2,3,4,6,7,8,9
              set logscale y
              set ytics format ""
              set ytics 1e-6, 10, 1
              set ytics add ("1" 1, ".1" 0.1, ".01" 0.01, "10^-3"
        0.001, \
                             "10^-4" 0.0001)
              set mytics 10
        Major tics with special formatting, minor tics at log positions

        By default, minor tics are off for linear axes and on for loga-
        rithmic axes.  They inherit the settings for aaxxiiss||bboorrddeerr and
        {{nnoo}}mmiirrrroorr specified for the major tics.  Please see sseett xxttiiccss
        for information about these.



        7788..4433..  MMyy22ttiiccss


        Minor tic marks along the y2 (right-hand) axis are controlled
        by sseett mmyy22ttiiccss.  Please see sseett mmxxttiiccss.



        7788..4444..  MMyyttiiccss


        Minor tic marks along the y axis are controlled by sseett mmyyttiiccss.
        Please see sseett mmxxttiiccss.



        7788..4455..  MMzzttiiccss


        Minor tic marks along the z axis are controlled by sseett mmzzttiiccss.
        Please see sseett mmxxttiiccss.














   GNUPLOT 4.1                                                      171


        7788..4466..  OObbjjeecctt


        The sseett oobbjjeecctt command defines a single object which will
        appear in all subsequent 2D plots. You may define as many
        objects as you like. Currently the supported object types are
        rreeccttaannggllee, cciirrccllee, eelllliippssee, and ppoollyyggoonn.  Rectangles inherit a
        default set of style properties (fill, color, border) from
        those set by the command sseett ssttyyllee rreeccttaannggllee, but each object
        can also be given individual style properties. Circles,
        ellipses, and polygons  inherit the fill style from sseett ssttyyllee
        ffiillll.

        Syntax:
            set object <index>
                <object-type> <object-properties>
                {front|back|behind} {fc|fillcolor <colorspec>} {fs
        <fillstyle>}
                {default} {lw|linewidth <width>}

        <object-type> is either rreeccttaannggllee, eelllliippssee, cciirrccllee, or ppoollyyggoonn.
        Each object type has its own set of characteristic properties.

        Setting ffrroonntt will draw the object in front of all plot ele-
        ments, but behind any labels that are also marked ffrroonntt. Set-
        ting bbaacckk will place the object behind all plot curves and
        labels. Setting bbeehhiinndd will place the object behind everything
        including the axes and bbaacckk rectangles, thus
            set object rectangle from screen 0,0 to screen 1,1 behind
        can be used to provide a colored background for the entire
        graph or page.

        The fill color of the object is taken from the <colorspec>.
        ffiillllccoolloorr may be abbreviated ffcc.  The fill style is taken from
        <fillstyle>.  See ccoolloorrssppeecc and ffiillllssttyyllee.  If the keyword
        ddeeffaauulltt is given, these properties are inherited from the
        default settings at the time a plot is drawn. See sseett ssttyyllee
        rreeccttaannggllee.




             7788..4466..11..  RReeccttaannggllee


             Syntax:
                 set object <index> rectangle
                     {from <position> {to|rto} <position> |
                      center <position> size <w>,<h> |
                      at <position> size <w>,<h>}

             The position of the rectangle may be specified by giving
             the position of two diagonal corners (bottom left and top










   GNUPLOT 4.1                                                      172


             right) or by giving the position of the center followed by
             the width and the height.  In either case the positions
             may be given in axis, graph, or screen coordinates. See
             ccoooorrddiinnaatteess.  The options aatt and cceenntteerr are synonyms.

             Examples:
                 # Force the entire area enclosed by the axes to have
             background color cyan
                 set object 1 rect from graph 0, graph 0 to graph 1,
             graph 1 back
                 set object 1 rect fc rgb "cyan" fillstyle solid 1.0

                 # Position a red square with lower left at 0,0 and
             upper right at 2,3
                 set object 2 rect from 0,0 to 2,3 fc lt 1

                 # Position an empty rectangle (no fill) with a blue
             border
                 set object 3 rect from 0,0 to 2,3 fs empty border rgb
             "blue"

                 # Return fill and color to the default style but leave
             vertices unchanged
                 set object 2 rect default



             7788..4466..22..  EElllliippssee


             Syntax:
                 set object <index> ellipse {at|center} <position> size
             <w>,<h>
                     {angle <orientation>}
                     {<other-object-properties>}

             The position of the ellipse is specified by giving the
             center followed by the width and the height (actually the
             major and minor axes). The keywords aatt and cceenntteerr are syn-
             onyms.  The center position may be given in axis, graph,
             or screen coordinates. See ccoooorrddiinnaatteess. The major and
             minor axis lengths must be given in axis coordinates.  The
             orientation of the ellipse is specified by the angle
             between the horizontal axis and the first axis of the
             ellipse.  NB: If the x and y axis scales are not equal,
             then the major/minor axis ratio will no longer be correct
             after rotation. This may be fixed in a later gnuplot ver-
             sion.

             Note that sseett oobbjjeecctt eelllliippssee ssiizzee <<22rr>>,,<<22rr>> does not in
             general produce the same result as sseett oobbjjeecctt cciirrccllee <<rr>>.
             The circle radius is always interpreted in terms of units
             along the x axis, and will always produce a circle even if










   GNUPLOT 4.1                                                      173


             the x and y axis scales are different and even if the
             aspect ratio of your plot is not 1.  'Set object ellipse'
             interprets the first '2r' in terms of x axis units and the
             second '2r' in terms of y axis units.  This will only pro-
             duce a circle if the x and y axis scales are identical and
             the plot aspect ratio is 1.




             7788..4466..33..  CCiirrccllee


             Syntax:
                 set object <index> circle {at|center} <position> size
             <radius>
                     {arc [<begin>:<end>]}
                     {<other-object-properties>}

             The position of the circle is specified by giving the
             position of the center center followed by the radius.  The
             keywords aatt and cceenntteerr are synonyms.  The position and
             radius may be given in x-axis, graph, or canvas coordi-
             nates. See ccoooorrddiinnaatteess. In all cases the radius is calcu-
             lated relative to the horizontal scale of the axis, graph,
             or canvas.  Any disparity between the horizontal and ver-
             tical scaling will be corrected for so that the result is
             always a circle.

             By default a full circle is drawn. The optional qualifier
             aarrcc specifies a starting angle and ending angle, in
             degrees, for one arc of the circle.  The arc is always
             drawn counterclockwise.




             7788..4466..44..  PPoollyyggoonn


             Syntax:
                 set object <index> polygon
                     from <position> to <position> ... {to <position>}
             or
                     from <position> rto <position> ... {rto <posi-
             tion>}

             The position of the polygon may be specified by giving the
             position of a sequence of vertices. These may be given in
             axis, graph, or screen coordinates.  If relative coordi-
             nates are used (rto) then the coordinate type must match
             that of the previous vertex.  See ccoooorrddiinnaatteess.











   GNUPLOT 4.1                                                      174


             Example:
                 set object 1 polygon from 0,0 to 1,1 to 2,0
                 set object 1 fc rgb "cyan" fillstyle solid 1.0 border
             lt -1




        7788..4477..  OOffffsseettss


        Offsets provide a mechanism to put an empty boundary around the
        data inside an autoscaled graph.  The offsets only affect the
        x1 and y1 axes, and only in 2D pplloott commands.

        Syntax:
              set offsets <left>, <right>, <top>, <bottom>
              unset offsets
              show offsets

        Each offset may be a constant or an expression.  Each defaults
        to 0.  By default, the left and right offsets are given in
        units of the first x axis, the top and bottom offsets in units
        of the first y axis.  Alternatively, you may specify the off-
        sets as a fraction of the total axis range by using the keyword
        "graph".  A positive offset expands the axis range in the spec-
        ified direction, e.g., a positive bottom offset makes ymin more
        negative.  Negative offsets, while permitted, can have unex-
        pected interactions with autoscaling and clipping.  To prevent
        the auto-scaling from further adjusting your axis ranges, it is
        useful to also specify "set auto fix".

        Example:
              set auto fix
              set offsets graph 0.05, 0, 2, 2
              plot sin(x)

        This graph of sin(x) will have a y range [-3:3] because the
        function will be autoscaled to [-1:1] and the vertical offsets
        are each two.  The x range will be [-11:10] because the default
        is [-10:10] and it has been expanded to the left by 0.05 of
        that total range.



        7788..4488..  OOrriiggiinn


        The sseett oorriiggiinn command is used to specify the origin of a plot-
        ting surface (i.e., the graph and its margins) on the screen.
        The coordinates are given in the ssccrreeeenn coordinate system (see
        ccoooorrddiinnaatteess for information about this system).











   GNUPLOT 4.1                                                      175


        Syntax:
              set origin <x-origin>,<y-origin>



        7788..4499..  OOuuttppuutt


        By default, screens are displayed to the standard output. The
        sseett oouuttppuutt command redirects the display to the specified file
        or device.

        Syntax:
              set output {"<filename>"}
              show output

        The filename must be enclosed in quotes.  If the filename is
        omitted, any output file opened by a previous invocation of sseett
        oouuttppuutt will be closed and new output will be sent to STDOUT.
        (If you give the command sseett oouuttppuutt ""SSTTDDOOUUTT"", your output may
        be sent to a file named "STDOUT"!  ["May be", not "will be",
        because some terminals, like xx1111 or wwxxtt, ignore sseett oouuttppuutt.])

        When both sseett tteerrmmiinnaall and sseett oouuttppuutt are used together, it is
        safest to give sseett tteerrmmiinnaall first, because some terminals set a
        flag which is needed in some operating systems.  This would be
        the case, for example, if the operating system needs to know
        whether or not a file is to be formatted in order to open it
        properly.

        On machines with popen functions (Unix), output can be piped
        through a shell command if the first non-whitespace character
        of the filename is '|'.  For instance,

              set output "|lpr -Plaser filename"
              set output "|lp -dlaser filename"

        On MSDOS machines, sseett oouuttppuutt ""PPRRNN"" will direct the output to
        the default printer.  On VMS, output can be sent directly to
        any spooled device.  It is also possible to send the output to
        DECnet transparent tasks, which allows some flexibility.



        7788..5500..  PPaarraammeettrriicc


        The sseett ppaarraammeettrriicc command changes the meaning of pplloott (sspplloott)
        from normal functions to parametric functions.  The command
        uunnsseett ppaarraammeettrriicc restores the plotting style to normal, single-
        valued expression plotting.

        Syntax:










   GNUPLOT 4.1                                                      176


              set parametric
              unset parametric
              show parametric

        For 2D plotting, a parametric function is determined by a pair
        of parametric functions operating on a parameter.  An example
        of a 2D parametric function would be pplloott ssiinn((tt)),,ccooss((tt)), which
        draws a circle (if the aspect ratio is set correctly---see sseett
        ssiizzee).  ggnnuupplloott will display an error message if both functions
        are not provided for a parametric pplloott.

        For 3D plotting, the surface is described as x=f(u,v),
        y=g(u,v), z=h(u,v).  Therefore a triplet of functions is
        required.  An example of a 3D parametric function would be
        ccooss((uu))**ccooss((vv)),,ccooss((uu))**ssiinn((vv)),,ssiinn((uu)), which draws a sphere.  ggnnuu--
        pplloott will display an error message if all three functions are
        not provided for a parametric sspplloott.

        The total set of possible plots is a superset of the simple
        f(x) style plots, since the two functions can describe the x
        and y values to be computed separately.  In fact, plots of the
        type t,f(t) are equivalent to those produced with f(x) because
        the x values are computed using the identity function.  Simi-
        larly, 3D plots of the type u,v,f(u,v) are equivalent to
        f(x,y).

        Note that the order the parametric functions are specified is
        xfunction, yfunction (and zfunction) and that each operates
        over the common parametric domain.

        Also, the sseett ppaarraammeettrriicc function implies a new range of val-
        ues.  Whereas the normal f(x) and f(x,y) style plotting assume
        an xrange and yrange (and zrange), the parametric mode addi-
        tionally specifies a trange, urange, and vrange.  These ranges
        may be set directly with sseett ttrraannggee, sseett uurraannggee, and sseett
        vvrraannggee, or by specifying the range on the pplloott or sspplloott com-
        mands.  Currently the default range for these parametric vari-
        ables is [-5:5].  Setting the ranges to something more meaning-
        ful is expected.



        7788..5511..  PPlloott


        The sshhooww pplloott command shows the current plotting command as it
        results from the last pplloott and/or sspplloott and possible subsequent
        rreepplloott commands.

        In addition, the sshhooww pplloott aadddd22hhiissttoorryy command adds this cur-
        rent plot command into the hhiissttoorryy. It is useful if you have
        used rreepplloott to add more curves to the current plot and you want
        to edit the whole command now.










   GNUPLOT 4.1                                                      177


        7788..5522..  PPmm33dd


        pm3d is an sspplloott style for drawing palette-mapped 3d and 4d
        data as color/gray maps and surfaces.  It uses a pm3d algorithm
        which allows plotting gridded as well as non-gridded data with-
        out preprocessing, even when the data scans do not have the
        same number of points.

        Drawing of color surfaces is available on terminals supporting
        filled colored polygons with color mapping specified by
        ppaalleettttee. Currently supported terminals include

          Screen terminals:
            OS/2 Presentation Manager
            X11
            Linux VGA (vgagl)
            GGI
            Windows
            AquaTerm (Mac OS X)
            wxWidgets (wxt)
          Files:
            PostScript
            pslatex, pstex, epslatex
            gif, png, jpeg
            (x)fig
            tgif
            cgm
            pdf
            svg
            emf

        Let us first describe how a map/surface is drawn.  The input
        data come from an evaluated function or from an sspplloott ddaattaa
        ffiillee.  Each surface consists of a sequence of separate scans
        (isolines).  The pm3d algorithm fills the region between two
        neighbouring points in one scan with another two points in the
        next scan by a gray (or color) according to z-values (or
        according to an additional 'color' column, see help for uussiinngg)
        of these 4 corners; by default the 4 corner values are aver-
        aged, but this can be changed by the option ccoorrnneerrss22ccoolloorr.  In
        order to get a reasonable surface, the neighbouring scans
        should not cross and the number of points in the neighbouring
        scans should not differ too much; of course, the best plot is
        with scans having same number of points.  There are no other
        requirements (e.g. the data need not be gridded).  Another
        advantage is that the pm3d algorithm does not draw anything
        outside of the input (measured or calculated) region.

        Surface coloring works with the following input data:

        1. splot of function or of data file with one or three data
        columns: The gray/color scale is obtained by mapping the










   GNUPLOT 4.1                                                      178


        averaged (or ccoorrnneerrss22ccoolloorr) z-coordinate of the four corners of
        the above-specified quadrangle into the range
        [min_color_z,max_color_z] of zzrraannggee or ccbbrraannggee providing a gray
        value in the range [0:1].  This value can be used directly as
        the gray for gray maps.  The normalized gray value can be fur-
        ther mapped into a color---see sseett ppaalleettttee for the complete
        description.

        2. splot of data file with two or four data columns: The
        gray/color value is obtained by using the last-column coordi-
        nate instead of the z-value, thus allowing the color and the z-
        coordinate be mutually independent.  This can be used for 4d
        data drawing.

        Other notes:

        1. The term 'scan' referenced above is used more among physi-
        cists than the term 'iso_curve' referenced in gnuplot documen-
        tation and sources.  You measure maps recorded one scan after
        another scan, that's why.

        2. The 'gray' or 'color' scale is a linear mapping of a contin-
        uous variable onto a smoothly varying palette of colors. The
        mapping is shown in a rectangle next to the main plot. This
        documentation refers to this as a "colorbox", and refers to the
        indexing variable as lying on the colorbox axis.  See sseett ccooll--
        oorrbbooxx, sseett ccbbrraannggee.

        3. To use pm3d coloring to generate a two-dimensional plot
        rather than a 3D surface, use sseett vviieeww mmaapp or sseett ppmm33dd mmaapp.

        Syntax (the options can be given in any order):
              set pm3d {
                         { at <bst combination> }
                         { interpolate <steps/points in scan, between
        scans> }
                         { scansautomatic | scansforward | scansback-
        ward | depthorder }
                         { flush { begin | center | end } }
                         { ftriangles | noftriangles }
                         { clip1in | clip4in }
                         { corners2color {
        mean|geomean|median|min|max|c1|c2|c3|c4 } }
                         { hidden3d <linestyle> | nohidden3d }
                         { implicit | explicit }
                         { map }
                       }
              show pm3d
              unset pm3d

        Color surface is drawn if data or function ssttyyllee is set to pm3d
        globally or via 'with' option, or if the option iimmpplliicciitt is
        on---then the pm3d surface is combined with the line surface










   GNUPLOT 4.1                                                      179


        mesh. See bottom of this section for mode details.

        Color surface can be drawn at the base or top (then it is a
        gray/color planar map) or at z-coordinates of surface points
        (gray/color surface).  This is defined by the aatt option with a
        string of up to 6 combinations of bb, tt and ss. For instance, aatt
        bb plots at bottom only, aatt sstt plots firstly surface and then
        top map, while aatt bbssttbbsstt will never by seriously used.

        Colored quadrangles are plotted one after another.  When plot-
        ting surfaces (aatt ss), the later quadrangles overlap (overdraw)
        the previous ones.  (Gnuplot is not virtual reality tool to
        calculate intersections of filled polygon meshes.)  You may try
        to switch between ssccaannssffoorrwwaarrdd and ssccaannssbbaacckkwwaarrdd to force the
        first scan of the data to be plotted first or last.  The
        default is ssccaannssaauuttoommaattiicc where gnuplot makes a guess about
        scans order.  On the other hand, the ddeepptthhoorrddeerr option com-
        pletely reorders the quadrangles. The rendering is performed
        after a depth sorting, which allows to visualize even compli-
        cated surfaces; see ppmm33dd ddeepptthhoorrddeerr for more details.

        If two subsequent scans do not have same number of points, then
        it has to be decided whether to start taking points for quad-
        rangles from the beginning of both scans (fflluusshh bbeeggiinn), from
        their ends (fflluusshh eenndd) or to center them (fflluusshh cceenntteerr).  Note,
        that fflluusshh ((cceenntteerr||eenndd)) are incompatible with ssccaannssaauuttoommaattiicc:
        if you specify fflluusshh cceenntteerr or fflluusshh eenndd and ssccaannssaauuttoommaattiicc is
        set, it is silently switched to ssccaannssffoorrwwaarrdd.

        If two subsequent scans do not have the same number of points,
        the option ffttrriiaanngglleess specifies whether color triangles are
        drawn at the scan tail(s) where there are not enough points in
        either of the scan. This can be used to draw a smooth map
        boundary.

        Clipping with respect to x, y coordinates of quadrangles can be
        done in two ways.  cclliipp11iinn: all 4 points of each quadrangle
        must be defined and at least 1 point of the quadrangle must lie
        in the x and y ranges.  cclliipp44iinn: all 4 points of each quadran-
        gle must lie in the x and y ranges.

        There is a single gray/color value associated to each drawn
        pm3d quadrangle (no smooth color change among vertices).  The
        value is calculated from z-coordinates from the surrounding
        corners according to ccoorrnneerrss22ccoolloorr <<ooppttiioonn>>.  The options
        'mean' (default), 'geomean' and 'median' produce various kinds
        of surface color smoothing, while options 'min' and 'max'
        choose minimal or maximal value, respectively. This may not be
        desired for pixel images or for maps with sharp and intense
        peaks, in which case the options 'c1', 'c2', 'c3' or 'c4' can
        be used instead to assign the quadrangle color based on the z-
        coordinate of only one corner.  Some experimentation may be
        needed to determine which corner corresponds to 'c1', as the










   GNUPLOT 4.1                                                      180


        orientation depends on the drawing direction.  Because the pm3d
        algorithm does not extend the colored surface outside the range
        of the input data points, the 'c<j>' coloring options will
        result in pixels along two edges of the grid not contributing
        to the color of any quadrangle.  For example, applying the pm3d
        algorithm to the 4x4 grid of data points in script
        ddeemmoo//ppmm33dd..ddeemm (please have a look) produces only (4-1)x(4-1)=9
        colored rectangles.

        44 ccoolluummnnss ooff ddaattaa ((xx,,yy,,zz,,ccoolloorr)): If a fourth column of data is
        provided, it is normally interpreted as a separate palette-
        mapped gray value. The coloring of individual quadrangles works
        as above, except that the color value is distinct from the z
        value.  As a separate coloring option, the fourth data column
        may provide instead an RGB color. See rrggbbccoolloorr vvaarriiaabbllee. In
        this case the plotting command must be

              splot ... using 1:2:3:4 with pm3d lc rgb variable

        Notice that ranges of z-values and color-values for surfaces
        are adjustable independently by sseett zzrraannggee, sseett ccbbrraannggee, as
        well as sseett lloogg for z or cb.  Maps can be adjusted by the cb-
        axis only; see also sseett vviieeww mmaapp and sseett ccoolloorrbbooxx.

        The option hhiiddddeenn33dd takes as the argument a linestyle which
        must be created by sseett ssttyyllee lliinnee ....... (The style need not to
        be present when setting pm3d, but it must be present when plot-
        ting).  If set, lines are drawn using the specified line style,
        taking into account hidden line removal.  This is by far more
        efficient than using the command sseett hhiiddddeenn33dd as it doesn't
        really calculate hidden line removal, but just draws the filled
        polygons in the correct order. So the recommended choice when
        using pm3d is
              set pm3d at s hidden3d 100
              set style line 100 lt 5 lw 0.5
              unset hidden3d
              unset surf
              splot x*x+y*y

        There used to be an option {transparent|solid} to this command.
        Now you get the same effect from sseett ggrriidd {{ffrroonntt||llaayyeerrddeeffaauulltt}},
        respectively.

        The sseett ppmm33dd mmaapp is an abbreviation for sseett ppmm33dd aatt bb; sseett vviieeww
        mmaapp; sseett ssttyyllee ddaattaa ppmm33dd; sseett ssttyyllee ffuunncc ppmm33dd;.  It is used for
        backwards compatibility, when sseett vviieeww mmaapp was not available.
        Take care that you properly use zzrraannggee and ccbbrraannggee for input
        data point filtering and color range scaling, respectively; and
        also sseett ((nnoo))ssuurrffaaccee seems to have a (side?) effect.

        The option iinntteerrppoollaattee mm,,nn will interpolate grid points into a
        finer mesh, and color each quadrangle appropriately.  For data
        files, this will smoothen the color surface, and enhance spikes










   GNUPLOT 4.1                                                      181


        in a color surface. For functions, interpolation makes little
        sense, except to trade off precision for memory.  It would usu-
        ally make more sense to use ssaammpplleess and iissoossaammpplleess when working
        with functions. For positive m and n, each quadrangle or trian-
        gle is interpolated m-times and n-times in the respective
        direction.  For negative m and n, the interpolation frequency
        is chosen so that there will be at least |m| and |n| points
        drawn; you can consider this as a special gridding function.
        Zeros, i.e. iinntteerrppoollaattiioonn 00,,00, will automatically choose an
        optimal number of interpolated surface points.

        The coloring setup as well as the color box drawing are deter-
        mined by sseett ppaalleettttee.  There can be only one palette for the
        current plot.  Drawing of several surfaces with different
        palettes can be achieved by mmuullttiipplloott with fixed oorriiggiinn and
        ssiizzee; don't forget to use sseett ppaalleettttee mmaaxxccoolloorrss when your ter-
        minal is running out of available colors.

        On gnuplot start-up, mode is eexxpplliicciitt. For historical and thus
        compatibility reasons, commands sseett ppmm33dd;; (i.e. no options) and
        sseett ppmm33dd aatt XX ...... (i.e.  aatt is the first option) sets mode
        iimmpplliicciitt. Further, sseett ppmm33dd;; sets up the other options to their
        default.

        If the option iimmpplliicciitt is on, all surface plots will be plotted
        additionally to the default type, e.g.
              splot 'fred.dat' with lines, 'lola.dat' with lines
        would give both plots (meshes) additionally to a pm3d surface.
        That's what you are used to after sseett ppmm33dd;;.

        If the option eexxpplliicciitt is on (or iimmpplliicciitt is off) only plots
        specified by the wwiitthh ppmm33dd attribute are plotted with a pm3d
        surface, e.g.:
              splot 'fred.dat' with lines, 'lola.dat' with pm3d
        would plot 'fred.dat' with lines (and only lines) and
        'lola.dat' with a pm3d surface.

        If you set the default data or function style to ppmm33dd, e.g.:
              set style data pm3d
        then the options iimmpplliicciitt and eexxpplliicciitt have no effect.

        Note that when plotting several plots, they are plotted in the
        order given on the command line. This can be of interest espe-
        cially for filled surfaces which can overwrite and therefore
        hide part of earlier plots.

        If wwiitthh ppmm33dd is specified in the sspplloott command line, then it
        accepts the 'at' option.  The following plots draw three color
        surfaces at different altitudes:
              set border 4095
              set pm3d at s
              splot 10*x with pm3d at b, x*x-y*y, x*x+y*y with pm3d at
        t










   GNUPLOT 4.1                                                      182


        See also help for sseett ppaalleettttee, sseett ccbbrraannggee, sseett ccoolloorrbbooxx, xx1111
        ppmm33dd and definitely the demo file ddeemmoo//ppmm33dd..ddeemm.




             7788..5522..11..  DDeepptthhoorrddeerr


             By default the quadrangles making up a pm3d solid surface
             are rendered in the order they are encountered along the
             surface grid points.  This order may be controlled by the
             options ssccaannssaauuttoommaattiicc|ssccaannssffoorrwwaarrdd|ssccaannssbbaacckkwwaarrdd.  These
             scan options are not in general compatible with hidden-
             surface removal.

             Gnuplot does not do true hidden surface removal for solid
             surfaces, but often it is sufficient to render the compo-
             nent quadrangles in order from furthest to closest.  This
             mode may be selected using the options
                   set pm3d depthorder hidden3d
             The ddeepptthhoorrddeerr option orders the solid quadrangles; the
             hhiiddddeenn33dd option similarly orders the bounding lines (if
             drawn).  Note that the global option sseett hhiiddddeenn33dd does not
             affect pm3d surfaces.



        7788..5533..  PPaalleettttee


        Palette is a color storage for use by ppmm33dd, filled color con-
        tours or polygons, color histograms, color gradient background,
        and whatever it is or it will be implemented...  Here it stands
        for a palette of smooth "continuous" colors or grays, but let's
        call it just a palette.

        Color palettes require terminal entries for filled color poly-
        gons and palettes of smooth colors, are currently available for
        terminals listed in help for sseett ppmm33dd. The range of color val-
        ues are adjustable independently by sseett ccbbrraannggee and sseett lloogg ccbb.
        The whole color palette is visualized in the ccoolloorrbbooxx.

        Syntax:
              set palette
              set palette {
                         { gray | color }
                         { gamma <gamma> }
                         {   rgbformulae <r>,<g>,<b>
                           | defined { ( <gray1> <color1> {, <grayN>
        <colorN>}... ) }
                           | file '<filename>' {datafile-modifiers}
                           | functions <R>,<G>,<B>










   GNUPLOT 4.1                                                      183


                         }
                         { model { RGB | HSV | CMY | YIQ | XYZ } }
                         { positive | negative }
                         { nops_allcF | ps_allcF }
                         { maxcolors <maxcolors> }
                       }
              show palette
              show palette palette <n> {{float | int}}
              show palette gradient
              show palette fit2rgbformulae
              show palette rgbformulae
              show colornames

        sseett ppaalleettttee (i.e. without options) sets up the default values.
        Otherwise, the options can be given in any order.  sshhooww ppaalleettttee
        shows the current palette properties.

        sshhooww ppaalleettttee ggrraaddiieenntt displays the gradient defining the
        palette (if appropriate).  sshhooww ppaalleettttee rrggbbffoorrmmuullaaee prints the
        available fixed gray --> color transformation formulae.  sshhooww
        ccoolloorrnnaammeess prints the known color names.

        sshhooww ppaalleettttee ppaalleettttee <<nn>> prints to the screen or to the file
        given by sseett pprriinntt a table of RGB triplets calculated for the
        current palette settings and a palette having <n> discrete col-
        ors.  The default wide table can be limited to 3 columns of
        r,g,b float values [0..1] or integer values [0..255] by options
        float or int, respectively.  This way, the current gnuplot
        color palette can be loaded into other imaging applications,
        for example Octave.  Additionally to this textual list of RGB
        table, you can use the tteesstt ppaalleettttee command to plot the R,G,B
        profiles for the current palette.

        The following options determine the coloring properties.

        Figure using this palette can be ggrraayy or ccoolloorr.  For instance,
        in ppmm33dd color surfaces the gray of each small spot is obtained
        by mapping the averaged z-coordinate of the 4 corners of sur-
        face quadrangles into the range [min_z,max_z] providing range
        of grays [0:1]. This value can be used directly as the gray for
        gray maps. The color map requires a transformation gray -->
        (R,G,B), i.e. a mapping [0:1] --> ([0:1],[0:1],[0:1]).

        Basically two different types of mappings can be used:  Ana-
        lytic formulae to convert gray to color, or discrete mapping
        tables which are interpolated.  ppaalleettttee rrggbbffoorrmmuullaaee and ppaalleettttee
        ffuunnccttiioonnss use analytic formulae whereas ppaalleettttee ddeeffiinneedd and
        ppaalleettttee ffiillee use interpolated tables.  ppaalleettttee rrggbbffoorrmmuullaaee
        reduces the size of postscript output to a minimum.

        The command sshhooww ppaalleettttee ffiitt22rrggbbffoorrmmuullaaee finds the best match-
        ing sseett ppaalleettttee rrggbbffoorrmmuullaaee for the current sseett ppaalleettttee. Natu-
        rally, it makes sense to use it for non-rgbformulae palettes.










   GNUPLOT 4.1                                                      184


        This command can be found useful mainly for external programs
        using the same rgbformulae definition of palettes as gnuplot,
        like zimg (
                  http://zimg.sourceforge.net
        ).

        sseett ppaalleettttee ggrraayy switches to a gray only palette. sseett ppaalleettttee
        rrggbbffoorrmmuullaaee, sseett ppaalleettttee ddeeffiinneedd, sseett ppaalleettttee ffiillee and sseett
        ppaalleettttee ffuunnccttiioonnss switch to a color mapping. sseett ppaalleettttee ccoolloorr
        is an easy way to switch back from the gray palette to the last
        color mapping.

        Automatic gamma correction via sseett ppaalleettttee ggaammmmaa <<ggaammmmaa>> can be
        done for gray maps only (sseett ppaalleettttee ggrraayy).  Linear mapping to
        gray is for gamma equals 1, see tteesstt ppaalleettttee.  Gamma is ignored
        for color mappings.

        Most terminals support only discrete number of colors (e.g. 256
        colors in gif).  All entries of the palette remaining after the
        default gnuplot linetype colors declaration are allocated for
        pm3d by default.  Then mmuullttiipplloott could fail if there are no
        more color positions in the terminal available.  Then you
        should use sseett ppaalleettttee mmaaxxccoolloorrss <<mmaaxxccoolloorrss>> with a reasonably
        small value.  This option can also be used to separate levels
        of z=constant in discrete steps, thus to emulate filled con-
        tours. Default value of 0 stays for allocating all remaining
        entries in the terminal palette or for to use exact mapping to
        RGB.

        RGB color space might not be the most useful color space to
        work in.  For that reason you may change the color space with
        mmooddeell to one of RRGGBB, HHSSVV, CCMMYY, YYIIQQ and XXYYZZ.  Using color names
        for sseett ppaalleettttee ddeeffiinneedd tables and a color space other than RGB
        will result in funny colors.  All explanation have been written
        for RGB color space, so please note, that RR can be HH, CC, YY, or
        XX, depending on the actual color space (GG and BB accordingly).

        All values for all color spaces are limited to [0,1].

        RGB stands for Red, Green and Blue;  CMY stands for Cyan,
        Magenta and Yellow; HSV stands for Hue, Saturation, and Value;
        YIQ is the color model used by the U.S. Commercial Color Tele-
        vision Broadcasting, it is basically an RGB recoding with down-
        ward compatibility for black and white television; XYZ are the
        three primary colors of the color model defined by the 'Commis-
        sion Internationale de l'Eclairage' (CIE).  For more informa-
        tion on color models see:
                  http://en.wikipedia.org/wiki/Color_space















   GNUPLOT 4.1                                                      185


             7788..5533..11..  RRggbbffoorrmmuullaaee


             For rrggbbffoorrmmuullaaee three suitable mapping functions have to
             be chosen.  This is done via rrggbbffoorrmmuullaaee <<rr>>,,<<gg>>,,<<bb>>.  The
             available mapping functions are listed by sshhooww ppaalleettttee
             rrggbbffoorrmmuullaaee.  Default is 77,,55,,1155, some other examples are
             33,,1111,,66, 2211,,2233,,33 or 33,,2233,,2211.  Negative numbers, like
             33,,--1111,,--66, mean inverted color (i.e.  1-gray passed into
             the formula, see also ppoossiittiivvee and nneeggaattiivvee options
             below).

             Some nice schemes in RGB color space
                7,5,15   ... traditional pm3d (black-blue-red-yellow)
                3,11,6   ... green-red-violet
                23,28,3  ... ocean (green-blue-white); try also all
             other permutations
                21,22,23 ... hot (black-red-yellow-white)
                30,31,32 ... color printable on gray (black-blue-vio-
             let-yellow-white)
                33,13,10 ... rainbow (blue-green-yellow-red)
                34,35,36 ... AFM hot (black-red-yellow-white)

             A full color palette in HSV color space
                3,2,2    ... red-yellow-green-cyan-blue-magenta-red

             Please note that even if called rrggbbffoorrmmuullaaee the formulas
             might actually determine the <H>,<S>,<V> or <X>,<Y>,<Z> or
             ... color components as usual.

             Use ppoossiittiivvee and nneeggaattiivvee to invert the figure colors.

             Note that it is possible to find a set of the best match-
             ing rgbformulae for any other color scheme by the command
                show palette fit2rgbformulae



             7788..5533..22..  DDeeffiinneedd


             Gray-to-rgb mapping can be manually set by use of ppaalleettttee
             ddeeffiinneedd:  A color gradient is defined and used to give the
             rgb values.  Such a  gradient is a piecewise linear map-
             ping from gray values in [0,1] to the RGB space
             [0,1]x[0,1]x[0,1].  You have to specify the gray values
             and the corresponding RGB values in between a linear
             interpolation shall take place:

             Syntax:
                   set palette  defined { ( <gray1> <color1> {, <grayN>
             <colorN>}... ) }











   GNUPLOT 4.1                                                      186


             <grayX> are gray values which are mapped to [0,1] and
             <colorX> are the corresponding rgb colors.  The color can
             be specified in three different ways:

                  <color> :=  { <r> <g> <b> | '<color-name>' |
             '#rrggbb' }

             Either by three numbers (each in [0,1]) for red, green and
             blue, separated by whitespace, or the name of the color in
             quotes or X style color specifiers also in quotes.  You
             may freely mix the three types in a gradient definition,
             but the named color "red" will be something strange if RGB
             is not selected as color space.  Use sshhooww ccoolloorrnnaammeess for a
             list of known color names.

             Please note, that even if written as <r>, this might actu-
             ally be the <H> component in HSV color space or <X> in
             CIE-XYZ space, or ...  depending on the selected color
             model.

             The <gray> values have to form an ascending sequence of
             real numbers; the sequence will be automatically rescaled
             to [0,1].

             sseett ppaalleettttee ddeeffiinneedd (without a gradient definition in
             braces) switches to RGB color space and uses a preset
             full-spectrum color gradient.  Use sshhooww ppaalleettttee ggrraaddiieenntt
             to display the gradient.

             Examples:

             To produce a gray palette (useless but instructive) use:
                   set palette model RGB
                   set palette defined ( 0 "black", 1 "white" )

             To produce a blue yellow red palette use (all equivalent):
                   set palette defined ( 0 "blue", 1 "yellow", 2 "red"
             )
                   set palette defined ( 0 0 0 1, 1 1 1 0, 2 1 0 0 )
                   set palette defined ( 0 "#0000ff", 1 "#ffff00", 2
             "#ff0000" )

             To produce some rainbow-like palette use:
                   set palette defined ( 0 "blue", 3 "green", 6 "yel-
             low", 10 "red" )

             Full color spectrum within HSV color space:
                   set palette model HSV
                   set palette defined ( 0 0 1 1, 1 1 1 1 )
                   set palette defined ( 0 0 1 0, 1 0 1 1, 6 0.8333 1
             1, 7 0.8333 0 1)

             To produce a palette with few colors only use:










   GNUPLOT 4.1                                                      187


                   set palette model RGB maxcolors 4
                   set palette defined ( 0 "blue", 1 "green", 2 "yel-
             low", 3 "red" )

             'Traffic light' palette (non-smooth color jumps at gray =
             1/3 and 2/3).
                   set palette model RGB
                   set palette defined (0 "dark-green", 1 "green", 1
             "yellow", \
                                        2 "dark-yellow", 2 "red", 3
             "dark-red" )




             7788..5533..33..  FFuunnccttiioonnss


             Use sseett ppaalleettttee ffuunnccttiioonnss <<RReexxpprr>>,, <<GGeexxpprr>>,, <<BBeexxpprr>> to
             define three formulae for the R(gray), G(gray) and B(gray)
             mapping.  The three formulae may depend on the variable
             ggrraayy which will take values in [0,1] and should also pro-
             duce values in [0,1].  Please note that <Rexpr> might be a
             formula for the H-value if HSV color space has been chosen
             (same for all other formulae and color spaces).

             Examples:

             To produce a full color palette use:
                   set palette model HSV functions gray, 1, 1

             A nice black to gold palette:
                   set palette model XYZ functions gray**0.35,
             gray**0.5, gray**0.8

             A gamma-corrected black and white palette
                   gamma = 2.2
                   color(gray) = gray**(1./gamma)
                   set palette model RGB functions color(gray),
             color(gray), color(gray)




             7788..5533..44..  FFiillee


             sseett ppaalleettttee ffiillee is basically a sseett ppaalleettttee ddeeffiinneedd ((<<ggrraa--
             ddiieenntt>>)) where <gradient> is read from a datafile.  Either
             4 columns (gray,R,G,B) or just three columns (R,G,B) have
             to be selected via the uussiinngg data file modifier.  In the
             three column case, the line number will be used as gray.
             The gray range is automatically rescaled to [0,1].  The










   GNUPLOT 4.1                                                      188


             file is read as a normal data file, so all datafile modi-
             fiers can be used.  Please note, that RR might actually be
             e.g. HH if HSV color space is selected.

             As usual <filename> may be ''--'' which means that the data
             follow the command inline and are terminated by a single ee
             on a line of its own.

             Use sshhooww ppaalleettttee ggrraaddiieenntt to display the gradient.

             Examples:

             Read in a palette of RGB triples each in range [0,255]:
                   set palette file 'some-palette' using
             ($1/255):($2/255):($3/255)

             Equidistant rainbow (blue-green-yellow-red) palette:
                   set palette model RGB file "-"
                   0 0 1
                   0 1 0
                   1 1 0
                   1 0 0
                   e

             Binary palette files are supported as well, see bbiinnaarryy
             ggeenneerraall. Example: put 64 triplets of R,G,B doubles into
             file palette.bin and load it by
                   set palette file "palette.bin" binary record=64
             using 1:2:3





             7788..5533..55..  GGaammmmaa ccoorrrreeccttiioonn


             For gray mappings gamma correction can be turned on by sseett
             ppaalleettttee ggaammmmaa <<ggaammmmaa>>.  <gamma> defaults to 1.5 which is
             quite suitable for most terminals.

             For color mappings no automatic gamma correction is done
             by gnuplot.  However, you may easily implement gamma cor-
             rection.  Here is an example for a gray scale image by use
             of explicit functions for the red, green and blue compo-
             nent with slightly different values of gamma

             Example:
                   set palette model RGB
                   set palette functions gray**0.64, gray**0.67,
             gray**0.70

             To use gamma correction with interpolated gradients










   GNUPLOT 4.1                                                      189


             specify intermediate gray values with appropriate colors.
             Instead of

                   set palette defined ( 0 0 0 0, 1 1 1 1 )

             use e.g.

                   set palette defined ( 0 0 0 0, 0.5 .73 .73 .73, 1 1
             1 1 )

             or even more intermediate points until the linear interpo-
             lation fits the "gamma corrected" interpolation well
             enough.




             7788..5533..66..  PPoossttssccrriipptt


             In order to reduce the size of postscript files, the gray
             value and not all three calculated r,g,b values are writ-
             ten to the file.  Therefore the analytical formulae are
             coded directly in the postscript language as a header just
             before the pm3d drawing, see /g and /cF definitions.  Usu-
             ally, it makes sense to write therein definitions of only
             the 3 formulae used.  But for multiplot or any other rea-
             son you may want to manually edit the transformations
             directly in the postscript file.  This is the default
             option nnooppss__aallllccFF.  Using the option ppss__aallllccFF writes post-
             script definitions of all formulae.  This you may find
             interesting if you want to edit the postscript file in
             order to have different palettes for different surfaces in
             one graph.  Well, you can achieve this functionality by
             mmuullttiipplloott with fixed oorriiggiinn and ssiizzee.

             If pm3d map has been plotted from gridded or almost regu-
             lar data with an output to a postscript file, then it is
             possible to reduce the size of this postscript file up to
             at about 50% by the enclosed awk script ppmm33ddCCoommpprreessss..aawwkk.
             This you may find  interesting if you intend to keep the
             file for including it into your publication or before
             downloading a very large file into a slow printer. Usage:
                 awk -f pm3dCompress.awk thefile.ps >smallerfile.ps

             If pm3d map has been plotted from rectangular gridded data
             with an output to a postscript file, then it is possible
             to reduce the file size even more by the enclosed awk
             script ppmm33ddCCoonnvveerrttTTooIImmaaggee..aawwkk.  Usage:
                 awk -f pm3dConvertToImage.awk <thefile.ps >smaller-
             file.ps

             You may manually change the postscript output from gray to










   GNUPLOT 4.1                                                      190


             color and vice versa and change the definition of <maxcol-
             ors>.



        7788..5544..  PPooiinnttiinntteerrvvaallbbooxx


        The ppooiinnttiinntteerrvvaall property of line types is used in plot style
        lliinneessppooiinnttss.  A negative value of pointinterval, e.g. -N, means
        that point symbols are drawn only for every Nth point, and that
        a box (actually circle) behind each point symbol is blanked out
        by filling with the background color.  The command sseett ppooiinnttiinn--
        tteerrvvaallbbooxx controls the radius of this blanked out region.



        7788..5555..  PPooiinnttssiizzee


        The sseett ppooiinnttssiizzee command scales the size of the points used in
        plots.

        Syntax:
              set pointsize <multiplier>
              show pointsize

        The default is a multiplier of 1.0.  Larger pointsizes may be
        useful to make points more visible in bitmapped graphics.

        The pointsize of a single plot may be changed on the pplloott com-
        mand.  See pplloott wwiitthh for details.

        Please note that the pointsize setting is not supported by all
        terminal types.



        7788..5566..  PPoollaarr


        The sseett ppoollaarr command changes the meaning of the plot from
        rectangular coordinates to polar coordinates.

        Syntax:
              set polar
              unset polar
              show polar

        In polar coordinates, the dummy variable (t) is an angle.  The
        default range of t is [0:2*pi], or, if degree units have been
        selected, to [0:360] (see sseett aanngglleess).











   GNUPLOT 4.1                                                      191


        The command uunnsseett ppoollaarr changes the meaning of the plot back to
        the default rectangular coordinate system.

        The sseett ppoollaarr command is not supported for ssppllootts.  See the sseett
        mmaappppiinngg command for similar functionality for ssppllootts.

        While in polar coordinates the meaning of an expression in t is
        really r = f(t), where t is an angle of rotation.  The trange
        controls the domain (the angle) of the function, and the x and
        y ranges control the range of the graph in the x and y direc-
        tions.  Each of these ranges, as well as the rrange, may be
        autoscaled or set explicitly.  Ffor details of all the rraannggeess
        commands, see sseett xxrraannggee.

        Example:
              set polar
              plot t*sin(t)
              plot [-2*pi:2*pi] [-3:3] [-3:3] t*sin(t)

        The first pplloott uses the default polar angular domain of 0 to
        2*pi.  The radius and the size of the graph are scaled automat-
        ically.  The second pplloott expands the domain, and restricts the
        size of the graph to [-3:3] in both directions.

        You may want to sseett ssiizzee ssqquuaarree to have ggnnuupplloott try to make the
        aspect ratio equal to unity, so that circles look circular.
        See also polar demos (polar.dem) and polar data plot (pol-
        dat.dem).



        7788..5577..  PPrriinntt


        The sseett pprriinntt command redirects the output of the pprriinntt command
        to a file.

        Syntax:
              set print
              set print "-"
              set print "<filename>"
              set print "<filename>" append
              set print "|<shell_command>"

        Without "<filename>", the output file is restored to <STDERR>.
        The <filename> "-" means <STDOUT>. The aappppeenndd flag causes the
        file to be opened in append mode.  A <filename> starting with
        "|" is opened as a pipe to the <shell_command> on platforms
        that support piping.














   GNUPLOT 4.1                                                      192


        7788..5588..  RRmmaarrggiinn


        The command sseett rrmmaarrggiinn sets the size of the right margin.
        Please see sseett mmaarrggiinn for details.



        7788..5599..  RRrraannggee


        The sseett rrrraannggee command sets the range of the radial coordinate
        for a graph in polar mode.  Please see sseett xxrraannggee for details.



        7788..6600..  SSaammpplleess


        The sampling rate of functions, or for interpolating data, may
        be changed by the sseett ssaammpplleess command.

        Syntax:
              set samples <samples_1> {,<samples_2>}
              show samples

        By default, sampling is set to 100 points.  A higher sampling
        rate will produce more accurate plots, but will take longer.
        This parameter has no effect on data file plotting unless one
        of the interpolation/approximation options is used.  See pplloott
        ssmmooootthh re 2D data and sseett ccnnttrrppaarraamm and sseett ddggrriidd33dd re 3D data.

        When a 2D graph is being done, only the value of <samples_1> is
        relevant.

        When a surface plot is being done without the removal of hidden
        lines, the value of samples specifies the number of samples
        that are to be evaluated for the isolines.  Each iso-v line
        will have <sample_1> samples and each iso-u line will have
        <sample_2> samples.  If you only specify <samples_1>, <sam-
        ples_2> will be set to the same value as <samples_1>.  See also
        sseett iissoossaammpplleess.



        7788..6611..  SSiizzee


        Syntax:
              set size {{no}square | ratio <r> | noratio}
        {<xscale>,<yscale>}
              show size











   GNUPLOT 4.1                                                      193


        The <xscale> and <yscale> values are scale factors for the size
        of the plot, which includes the graph, labels, and margins.

        Important note:
              In earlier versions of gnuplot, some terminal types used
        the values from
              `set size` to control also the size of the output canvas;
        others did not.
              In version 4.4 almost all terminals now follow the fol-
        lowing convention:

        sseett tteerrmm <<tteerrmmiinnaall__ttyyppee>> ssiizzee <<XXXX>>,, <<YYYY>> controls the size of
        the output file, or ccaannvvaass. Please see individual terminal doc-
        umentation for allowed values of the size parameters.  By
        default, the plot will fill this canvas.

        sseett ssiizzee <<XXXX>>,, <<YYYY>> scales the plot itself relative to the size
        of the canvas.  Scale values less than 1 will cause the plot to
        not fill the entire canvas.  Scale values larger than 1 will
        cause only a portion of the plot to fit on the canvas.  Please
        be aware that setting scale values larger than 1 may cause
        problems on some terminal types.

        rraattiioo causes ggnnuupplloott to try to create a graph with an aspect
        ratio of <r> (the ratio of the y-axis length to the x-axis
        length) within the portion of the plot specified by <xscale>
        and <yscale>.

        The meaning of a negative value for <r> is different.  If
        <r>=-1, gnuplot tries to set the scales so that the unit has
        the same length on both the x and y axes (suitable for geo-
        graphical data, for instance).  If <r>=-2, the unit on y has
        twice the length of the unit on x, and so on.

        The success of ggnnuupplloott in producing the requested aspect ratio
        depends on the terminal selected.  The graph area will be the
        largest rectangle of aspect ratio <r> that will fit into the
        specified portion of the output (leaving adequate margins, of
        course).

        ssqquuaarree is a synonym for rraattiioo 11.

        Both nnoorraattiioo and nnoossqquuaarree return the graph to the default
        aspect ratio of the terminal, but do not return <xscale> or
        <yscale> to their default values (1.0).

        rraattiioo and ssqquuaarree have no effect on 3D plots, but do affect 3D
        projections created using sseett vviieeww mmaapp.  See also sseett vviieeww
        eeqquuaall, which forces the x and y axes of a 3D onto the same
        scale.

        Examples:











   GNUPLOT 4.1                                                      194


        To set the size so that the plot fills the available canvas:
              set size 1,1

        To make the graph half size and square use:
              set size square 0.5,0.5

        To make the graph twice as high as wide use:
              set size ratio 2

        See also airfoil demo.



        7788..6622..  SSttyyllee


        Default plotting styles are chosen with the sseett ssttyyllee ddaattaa and
        sseett ssttyyllee ffuunnccttiioonn commands.  See pplloott wwiitthh for information
        about how to override the default plotting style for individual
        functions and data sets.  See pplloottttiinngg ssttyylleess for a complete
        list of styles.

        Syntax:
              set style function <style>
              set style data <style>
              show style function
              show style data

        Default styles for specific plotting elements may also be set.

        Syntax:
              set style arrow <n> <arrowstyle>
              set style fill <fillstyle>
              set style histogram <histogram style options>
              set style line <n> <linestyle>





             7788..6622..11..  SSeett ssttyyllee aarrrrooww


             Each terminal has a default set of arrow and point types,
             which can be seen by using the command tteesstt.  sseett ssttyyllee
             aarrrrooww defines a set of arrow types and widths and point
             types and sizes so that you can refer to them later by an
             index instead of repeating all the information at each
             invocation.

             Syntax:
                   set style arrow <index> default
                   set style arrow <index> {nohead | head | heads}










   GNUPLOT 4.1                                                      195


                                           {size
             <length>,<angle>{,<backangle>}}
                                           {filled | empty | nofilled}
                                           {front | back}
                                           { {linestyle | ls
             <line_style>}
                                             | {linetype | lt
             <line_type>}
                                               {linewidth | lw
             <line_width} }
                   unset style arrow
                   show style arrow

             <index> is an integer that identifies the arrowstyle.

             If ddeeffaauulltt is given all arrow style parameters are set to
             their default values.

             If the linestyle <index> already exists, only the given
             parameters are changed while all others are preserved.  If
             not, all undefined values are set to the default values.

             Specifying nnoohheeaadd produces arrows drawn without a head---a
             line segment.  This gives you yet another way to draw a
             line segment on the plot.  By default, arrows have one
             head. Specifying hheeaaddss draws arrow heads on both ends of
             the line.

             Head size can be controlled by ssiizzee <<lleennggtthh>>,,<<aannggllee>> or
             ssiizzee <<lleennggtthh>>,,<<aannggllee>>,,<<bbaacckkaannggllee>>, where <<lleennggtthh>> defines
             length of each branch of the arrow head and <<aannggllee>> the
             angle (in degrees) they make with the arrow.  <<LLeennggtthh>> is
             in x-axis units; this can be changed by ffiirrsstt, sseeccoonndd,
             ggrraapphh, ssccrreeeenn, or cchhaarraacctteerr before the <length>;  see
             ccoooorrddiinnaatteess for details.  <<BBaacckkaannggllee>> only takes effect
             when ffiilllleedd or eemmppttyy is also used.  Then, <<bbaacckkaannggllee>> is
             the angle (in degrees) the back branches make with the
             arrow (in the same direction as <<aannggllee>>).  The ffiigg termi-
             nal has a restricted backangle function. It supports three
             different angles. There are two thresholds: Below 70
             degrees, the arrow head gets an indented back angle. Above
             110 degrees, the arrow head has an acute back angle.
             Between these thresholds, the back line is straight.

             Specifying ffiilllleedd produces filled arrow heads (if heads
             are used).  Filling is supported on filled-polygon capable
             terminals, see help of ppmm33dd for their list, otherwise the
             arrow heads are closed but not filled.  The same result
             (closed but not filled arrow head) is reached by specify-
             ing eemmppttyy.  Further, filling and outline is obviously not
             supported on terminals drawing arrows by their own spe-
             cific routines, like mmeettaaffoonntt, mmeettaappoosstt, llaatteexx or ttggiiff.











   GNUPLOT 4.1                                                      196


             The line style may be selected from a user-defined list of
             line styles (see sseett ssttyyllee lliinnee) or may be defined here by
             providing values for <<lliinnee__ttyyppee>> (an index from the
             default list of styles) and/or <<lliinnee__wwiiddtthh>> (which is a
             multiplier for the default width).

             Note, however, that if a user-defined line style has been
             selected, its properties (type and width) cannot be
             altered merely by issuing another sseett ssttyyllee aarrrrooww command
             with the appropriate index and lltt or llww.

             If ffrroonntt is given, the arrows are written on top of the
             graphed data. If bbaacckk is given (the default), the arrow is
             written underneath the graphed data.  Using ffrroonntt will
             prevent a arrow from being obscured by dense data.

             Examples:

             To draw an arrow without an arrow head and double width,
             use:
                   set style arrow 1 nohead lw 2
                   set arrow arrowstyle 1

             See also sseett aarrrrooww for further examples.




             7788..6622..22..  SSeett ssttyyllee ddaattaa


             The sseett ssttyyllee ddaattaa command changes the default plotting
             style for data plots.

             Syntax:
                   set style data <plotting-style>
                   show style data

             See pplloottttiinngg ssttyylleess for the choices.  If no choice is
             given, the choices are listed.  sshhooww ssttyyllee ddaattaa shows the
             current default data plotting style.



             7788..6622..33..  SSeett ssttyyllee ffiillll


             The sseett ssttyyllee ffiillll command is used to set the default
             style of the plot elements in plots with boxes, his-
             tograms, candlesticks and filledcurves.  This default can
             be superseded by fillstyles attached to individual plots.
             See also 'set style rectangle'.











   GNUPLOT 4.1                                                      197


             Syntax:
                   set style fill {empty
                                   | {transparent} solid {<density>}
                                   | {transparent} pattern {<n>}}
                                  {border {lt} {lc <colorspec>} |
             noborder}

             The default fillstyle is eemmppttyy.

             The ssoolliidd option causes filling with a solid color, if the
             terminal supports that. The <density> parameter specifies
             the intensity of the fill color. At a <density> of 0.0,
             the box is empty, at <density> of 1.0, the inner area is
             of the same color as the current linetype.  Some terminal
             types can vary the density continuously; others implement
             only a few levels of partial fill.  If no <density> param-
             eter is given, it defaults to 1.

             The ppaatttteerrnn option causes filling to be done with a fill
             pattern supplied by the terminal driver.  The kind and
             number of available fill patterns depend on the terminal
             driver.  If multiple datasets using filled boxes are plot-
             ted, the pattern cycles through all available pattern
             types, starting from pattern <n>, much as the line type
             cycles for multiple line plots.

             The eemmppttyy option causes filled boxes not to be filled.
             This is the default.

             By default, bboorrddeerr, the box is bounded by a solid line of
             the current linetype. bboorrddeerr <<ccoolloorrssppeecc>> allows you to
             change the color of the border.  nnoobboorrddeerr specifies that
             no bounding lines are drawn.




                  7788..6622..33..11..  SSeett ssttyyllee ffiillll ttrraannssppaarreenntt


                  Some terminals support the attribute ttrraannssppaarreenntt for
                  filled areas.  In the case of transparent solid fill
                  areas, the ddeennssiittyy parameter is interpreted as an
                  alpha value; that is, density 0 is fully transparent,
                  density 1 is fully opaque.  In the case of transpar-
                  ent pattern fill, the background of the pattern is
                  either fully transparent or fully opaque.
















   GNUPLOT 4.1                                                      198


                          +---------------------+
                          |Terminal   solid     |
                          +---------------------+
                          |  gif      no        |
                          |  jpeg     yes       |
                          |  pdf      yes       |
                          |  png      TrueColor |
                          |  post     no        |
                          |  svg      yes       |
                          |  wxt      yes       |
                          |  x11      no        |
                          +---------------------+
                          +---------------------+


   Note that there may be additional limitations on the creation or
   viewing of graphs containing transparent fill areas.  For example,
   the png terminal can only use transparent fill if the "truecolor"
   option is set.  Some pdf viewers may not correctly display the fill
   areas even if they are correctly described in the pdf file.
   Ghostscript/gv does not correctly display pattern-fill areas even
   though actual PostScript printers generally have no problem.



             7788..6622..44..  SSeett ssttyyllee ffuunnccttiioonn


             The sseett ssttyyllee ffuunnccttiioonn command changes the default plot-
             ting style for function plots.

             Syntax:
                   set style function <plotting-style>
                   show style function

             See pplloottttiinngg ssttyylleess for the choices.  If no choice is
             given, the choices are listed.  sshhooww ssttyyllee ffuunnccttiioonn shows
             the current default function plotting style.



             7788..6622..55..  SSeett ssttyyllee iinnccrreemmeenntt


             Syntax:
                   set style increment {default|userstyles}
                   show style increment

             By default, successive plots within the same graph will
             use successive linetypes from the default set for the cur-
             rent terminal type.  However, choosing sseett ssttyyllee iinnccrreemmeenntt
             uusseerr allows you to step through the user-defined line
             styles rather than through the default linetypes.










   GNUPLOT 4.1                                                      199


             Example:

                   set style line 1 lw 2 lc rgb "gold"
                   set style line 2 lw 2 lc rgb "purple"
                   set style line 4 lw 1 lc rgb "sea-green"
                   set style increment user

                   plot f1(x), f2(x), f3(x), f4(x)

             should plot functions f1, f2, f4 in your 3 newly defined
             line styles.  If a user-defined line style is not found
             then the corresponding default linetype is used instead.
             E.g. in the example above, f3(x) will be plotted using the
             default linetype 3.




             7788..6622..66..  SSeett ssttyyllee lliinnee


             Each terminal has a default set of line and point types,
             which can be seen by using the command tteesstt.  sseett ssttyyllee
             lliinnee defines a set of line types and widths and point
             types and sizes so that you can refer to them later by an
             index instead of repeating all the information at each
             invocation.

             Syntax:
                   set style line <index> default
                   set style line <index> {{linetype  | lt} <line_type>
             | <colorspec>}
                                          {{linecolor | lc} <color-
             spec>}
                                          {{linewidth | lw}
             <line_width>}
                                          {{pointtype | pt}
             <point_type>}
                                          {{pointsize | ps}
             <point_size>}
                                          {{pointinterval | pi} <inter-
             val>}
                                          {palette}
                   unset style line
                   show style line

             If ddeeffaauulltt is given all line style parameters are set to
             their default values.

             If the linestyle <index> already exists, only the given
             parameters are changed while all others are preserved.  If
             not, all undefined values are set to the default values.











   GNUPLOT 4.1                                                      200


             The line and point types default to the index value. The
             exact symbol that is drawn for that index value may vary
             from one terminal type to another.

             The line width and point size are multipliers for the cur-
             rent terminal's default width and size (but note that
             <point_size> here is unaffected by the multiplier given by
             the commandsseett ppooiinnttssiizzee).

             The ppooiinnttiinntteerrvvaall controls the spacing between points in a
             plot drawn with style lliinneessppooiinnttss.  The default is 0
             (every point is drawn). For example, sseett ssttyyllee lliinnee NN ppii 33
             defines a linestyle that uses pointtype N, pointsize and
             linewidth equal to the current defaults for the terminal,
             and will draw every 3rd point in plots using wwiitthh lliinneess--
             ppooiinnttss.  A negative value for the interval is treated the
             same as a positive value, except that some terminals will
             try to interrupt the line where it passes through the
             point symbol.

             Linestyles created by this mechanism do not replace the
             default linetype styles; both may be used.  If you want
             plots to use the defined styles in preference to the
             default linetypes, please see sseett ssttyyllee iinnccrreemmeenntt.

             Not all terminals support the lliinneewwiiddtthh and ppooiinnttssiizzee fea-
             tures; if not supported, the option will be ignored.

             Terminal-independent colors may be assigned using either
             lliinneeccoolloorr <<ccoolloorrssppeecc>> or lliinneettyyppee <<ccoolloorrssppeecc>>, abbreviated
             llcc or lltt.  This requires giving a RGB color triple, a
             known palette color name, a fractional index into the cur-
             rent palette, or a constant value from the current mapping
             of the palette onto cbrange.  See ccoolloorrss, ccoolloorrssppeecc, sseett
             ppaalleettttee, ccoolloorrnnaammeess, ccbbrraannggee.

             sseett ssttyyllee lliinnee <<nn>> lliinneettyyppee <<lltt>> will set both a terminal-
             dependent dot/dash pattern and color. The commandssseett
             ssttyyllee lliinnee <<nn>> lliinneeccoolloorr <<ccoolloorrssppeecc>> or sseett ssttyyllee lliinnee <<nn>>
             lliinneettyyppee <<ccoolloorrssppeecc>> will set a new line color while leav-
             ing the existing dot-dash pattern unchanged.

             In 3d mode (sspplloott command), the special keyword ppaalleettttee is
             allowed as a shorthand for "linetype palette z".  The
             color value corresponds to the z-value (elevation) of the
             splot, and varies smoothly along a line or surface.

             Examples: Suppose that the default lines for indices 1, 2,
             and 3 are red, green, and blue, respectively, and the
             default point shapes for the same indices are a square, a
             cross, and a triangle, respectively.  Then

                   set style line 1 lt 2 lw 2 pt 3 ps 0.5










   GNUPLOT 4.1                                                      201


             defines a new linestyle that is green and twice the
             default width and a new pointstyle that is a half-sized
             triangle.  The commands

                   set style function lines
                   plot f(x) lt 3, g(x) ls 1

             will create a plot of f(x) using the default blue line and
             a plot of g(x) using the user-defined wide green line.
             Similarly the commands

                   set style function linespoints
                   plot p(x) lt 1 pt 3, q(x) ls 1

             will create a plot of p(x) using the default triangles
             connected by a red line and q(x) using small triangles
             connected by a green line.

                   splot sin(sqrt(x*x+y*y))/sqrt(x*x+y*y) w l pal

             creates a surface plot using smooth colors according to
             ppaalleettttee. Note, that this works only on some terminals. See
             also sseett ppaalleettttee, sseett ppmm33dd.

                   set style line 10 linetype 1 linecolor rgb "cyan"

             will assign linestyle 10 to be a solid cyan line on any
             terminal that supports rgb colors.




             7788..6622..77..  SSeett ssttyyllee cciirrccllee



             Syntax:
                   set style circle {radius {graph|screen} <R>}

             This command sets the default radius used in plot style
             "with circles".  It applies to data plots with only 2 col-
             umns of data (x,y) and to function plots.  The default is
             "set style circle radius graph 0.02".




             7788..6622..88..  SSeett ssttyyllee rreeccttaannggllee



             Rectangles defined with the sseett oobbjjeecctt command can have
             individual styles.  However, if the object is not assigned










   GNUPLOT 4.1                                                      202


             a private style then it inherits a default that is taken
             from the sseett ssttyyllee rreeccttaannggllee command.

             Syntax:
                 set style rectangle {front|back} {lw|linewidth <lw>}
                                     {fillcolor <colorspec>} {fs <fill-
             style>}

             See ccoolloorrssppeecc and ffiillllssttyyllee.  ffiillllccoolloorr may be abbreviated
             as ffcc.

             Examples:
                 set style rectangle back fc rgb "white" fs solid 1.0
             border lt -1
                 set style rectangle fc linsestyle 3 fs pattern 2
             noborder

             The default values correspond to solid fill with the back-
             ground color and a black border.




        7788..6633..  SSuurrffaaccee


        The command sseett ssuurrffaaccee controls the display of surfaces by
        sspplloott.

        Syntax:
              set surface
              unset surface
              show surface

        The surface is drawn with the style specified by wwiitthh, or else
        the appropriate style, data or function.

        uunnsseett ssuurrffaaccee will cause sspplloott to not draw points or lines cor-
        responding to any of the function or data file points.  If you
        want to turn off the surface for an individual function or data
        file while leaving the others active, use the nnoossuurrffaaccee keyword
        in the sspplloott command.  Contours may still be drawn on the sur-
        face, depending on the sseett ccoonnttoouurr option.  The combination
        uunnsseett ssuurrffaaccee;; sseett ccoonnttoouurr bbaassee is useful for displaying con-
        tours on the grid base.  See also sseett ccoonnttoouurr.



        7788..6644..  TTaabbllee


        When ttaabbllee mode is enabled, pplloott and sspplloott commands print out a
        multicolumn ASCII table of X Y {Z} R values rather than










   GNUPLOT 4.1                                                      203


        creating an actual plot on the current terminal.  The character
        R takes on one of three values: "i" if the point is in the
        active range, "o" if it is out-of-range, or "u" if it is unde-
        fined.  The data format is determined by the format of the axis
        labels (see sseett ffoorrmmaatt), and the columns are separated by sin-
        gle spaces.  This can be useful if you want to generate con-
        tours and then save them for further use, perhaps for plotting
        with pplloott;  see sseett ccoonnttoouurr for example.  The same method can
        be used to save interpolated data (see sseett ssaammpplleess and sseett
        ddggrriidd33dd).

        Syntax:
              set table {"outfile"}
              plot <whatever>
              unset table

        Tabular output is written to the named file, if any, otherwise
        it is written to the current value of sseett oouuttppuutt.  You must
        explicitly uunnsseett ttaabbllee in order to go back to normal plotting
        on the current terminal.



        7788..6655..  TTeerrmmiinnaall


        ggnnuupplloott supports many different graphics devices.  Use sseett tteerr--
        mmiinnaall to tell ggnnuupplloott what kind of output to generate. Use sseett
        oouuttppuutt to redirect that output to a file or device.

        Syntax:
              set terminal {<terminal-type> | push | pop}
              show terminal

        If <terminal-type> is omitted, ggnnuupplloott will list the available
        terminal types.  <terminal-type> may be abbreviated.

        If both sseett tteerrmmiinnaall and sseett oouuttppuutt are used together, it is
        safest to give sseett tteerrmmiinnaall first, because some terminals set a
        flag which is needed in some operating systems.

        Several terminals have many additional options.  For example,
        see ppnngg, or ppoossttssccrriipptt.  The options used by a previous invoca-
        tion sseett tteerrmm <<tteerrmm>> <<ooppttiioonnss>> of a given <<tteerrmm>> are remem-
        bered, thus subsequent sseett tteerrmm <<tteerrmm>> does not reset them.
        This helps in printing, for instance, when switching among dif-
        ferent terminals---previous options don't have to be repeated.

        The command sseett tteerrmm ppuusshh remembers the current terminal
        including its settings while sseett tteerrmm ppoopp restores it. This is
        equivalent to ssaavvee tteerrmm and llooaadd tteerrmm, but without accessing
        the filesystem. Therefore they can be used to achieve platform
        independent restoring of the terminal after printing, for










   GNUPLOT 4.1                                                      204


        instance. After gnuplot's startup, the default terminal or that
        from ssttaarrttuupp file is pushed automatically. Therefore portable
        scripts can rely that sseett tteerrmm ppoopp restores the default termi-
        nal on a given platform unless another terminal has been pushed
        explicitly.

        For more information, see the ccoommpplleettee lliisstt ooff tteerrmmiinnaallss.



        7788..6666..  TTeerrmmooppttiioonn


        The sseett tteerrmmooppttiioonn command allows you to change the behaviour
        of the current terminal without requiring a new sseett tteerrmmiinnaall
        command. Only one option can be changed per command, and only a
        small number of options can be changed this way. Currently the
        only options accepted are

             set termoption {no}enhanced
             set termoption font "<fontname>{,<fontsize>}"
             set termoption {solid|dashed}
             set termoption {linewidth <lw>}{lw <lw>}




        7788..6677..  TTiiccss


        Control of the major (labelled) tics on all axes at once is
        possible with the sseett ttiiccss command.

        Fine control of the major (labelled) tics on all axes at once
        is possible with the sseett ttiiccss command.  The tics may be turned
        off with the uunnsseett ttiiccss command, and may be turned on (the
        default state) with sseett ttiiccss.  Similar commands (by preceding
        'tics' by the axis name) control the major tics on a single
        axis.

        Syntax:
              set tics {axis | border} {{no}mirror}
                       {in | out} {scale {default | <major>
        {,<minor>}}}
                       {{no}rotate {by <ang>}} {offset <offset> |
        nooffset}
                       { format "formatstring" } { font "name{,<size>}"
        }
                       { textcolor <colorspec> }
              set tics {front | back}
              unset tics
              show tics











   GNUPLOT 4.1                                                      205


        The options in the first set above can be applied individually
        to any or all axes, i.e., x, y, z, x2, y2, and cb.

        Set tics ffrroonntt or bbaacckk applies to all axes at once, but only
        for 2D plots (not splot).  It controls whether the tics are
        placed behind or in front of the plot elements, in the case
        that there is overlap.

        aaxxiiss or bboorrddeerr tells ggnnuupplloott to put the tics (both the tics
        themselves and the accompanying labels) along the axis or the
        border, respectively.  If the axis is very close to the border,
        the aaxxiiss option will move the tic labels to outside the border
        in case the border is printed (see sseett bboorrddeerr).  The relevant
        margin settings will usually be sized badly by the automatic
        layout algorithm in this case.

        mmiirrrroorr tells ggnnuupplloott to put unlabelled tics at the same posi-
        tions on the opposite border.  nnoommiirrrroorr does what you think it
        does.

        iinn and oouutt change the tic marks to be drawn inwards or out-
        wards.

        With ssccaallee, the size of the tic marks can be adjusted. If
        <minor> is not specified, it is 0.5*<major>.  The default size
        1.0 for major tics and 0.5 for minor tics is requested by ssccaallee
        ddeeffaauulltt.

        rroottaattee asks ggnnuupplloott to rotate the text through 90 degrees,
        which will be done if the terminal driver in use supports text
        rotation.  nnoorroottaattee cancels this. rroottaattee bbyy <<aanngg>> asks for
        rotation by <ang> degrees, supported by some terminal types.

        The defaults are bboorrddeerr mmiirrrroorr nnoorroottaattee for tics on the x and y
        axes, and bboorrddeerr nnoommiirrrroorr nnoorroottaattee for tics on the x2 and y2
        axes.  For the z axis, the default is nnoommiirrrroorr.

        The <offset> is specified by either x,y or x,y,z, and may be
        preceded by ffiirrsstt, sseeccoonndd, ggrraapphh, ssccrreeeenn, or cchhaarraacctteerr to
        select the coordinate system. <offset> is the offset of the
        tics texts from their default positions, while the default
        coordinate system is cchhaarraacctteerr.  See ccoooorrddiinnaatteess for details.
        nnooooffffsseett switches off the offset.

        sseett ttiiccss with no options restores to place tics inwards. Every
        other options are retained.

        See also sseett xxttiiccss for more control of major (labelled) tic
        marks and sseett mmxxttiiccss for control of minor tic marks.  These
        commands provide control at a axis by axis basis.













   GNUPLOT 4.1                                                      206


        7788..6688..  TTiiccsslleevveell


        Deprecated. See sseett xxyyppllaannee.



        7788..6699..  TTiiccssccaallee


        The sseett ttiiccssccaallee command is deprecated, use sseett ttiiccss ssccaallee
        instead.



        7788..7700..  TTiimmeessttaammpp


        The command sseett ttiimmeessttaammpp places the time and date of the plot
        in the left margin.

        Syntax:
              set timestamp {"<format>"} {top|bottom} {{no}rotate}
                            {offset <xoff>{,<yoff>}} {font
        "<fontspec>"}
              unset timestamp
              show timestamp

        The format string allows you to choose the format used to write
        the date and time.  Its default value is what asctime() uses:
        "%a %b %d %H:%M:%S %Y" (weekday, month name, day of the month,
        hours, minutes, seconds, four-digit year).  With ttoopp or bboottttoomm
        you can place the timestamp at the top or bottom of the left
        margin (default: bottom).  rroottaattee lets you write the timestamp
        vertically, if your terminal supports vertical text.  The con-
        stants <xoff> and <yoff> are offsets that let you adjust the
        position more finely.  <font> is used to specify the font with
        which the time is to be written.

        The abbreviation ttiimmee may be used in place of ttiimmeessttaammpp.

        Example:
              set timestamp "%d/%m/%y %H:%M" offset 80,-2 font "Hel-
        vetica"

        See sseett ttiimmeeffmmtt for more information about time format strings.



        7788..7711..  TTiimmeeffmmtt













   GNUPLOT 4.1                                                      207


        This command applies to timeseries where data are composed of
        dates/times.  It has no meaning unless the command sseett xxddaattaa
        ttiimmee is given also.

        Syntax:
              set timefmt "<format string>"
              show timefmt

        The string argument tells ggnnuupplloott how to read timedata from the
        datafile.  The valid formats are:




     +---------------------------------------------------------------+
     |Format   Explanation                                           |
     +---------------------------------------------------------------+
     |  %d     day of the month, 1--31                               |
     |  %m     month of the year, 1--12                              |
     |  %y     year, 0--99                                           |
     |  %Y     year, 4-digit                                         |
     |  %j     day of the year, 1--365                               |
     |  %H     hour, 0--24                                           |
     |  %M     minute, 0--60                                         |
     |  %s     seconds since the Unix epoch (1970-01-01 00:00 UTC)   |
     |  %S     second, 0--60                                         |
     |  %b     three-character abbreviation of the name of the month |
     |  %B     name of the month                                     |
     +---------------------------------------------------------------+
     +---------------------------------------------------------------+


   Any character is allowed in the string, but must match exactly.  \t
   (tab) is recognized.  Backslash-octals (\nnn) are converted to char.
   If there is no separating character between the time/date elements,
   then %d, %m, %y, %H, %M and %S read two digits each, %Y reads four
   digits and %j reads three digits.  %b requires three characters, and
   %B requires as many as it needs.

   Spaces are treated slightly differently.  A space in the string
   stands for zero or more whitespace characters in the file.  That is,
   "%H %M" can be used to read "1220" and "12     20" as well as "12
   20".

   Each set of non-blank characters in the timedata counts as one col-
   umn in the uussiinngg nn::nn specification.  Thus 1111::1111  2255//1122//7766  2211..00 con-
   sists of three columns.  To avoid confusion, ggnnuupplloott requires that
   you provide a complete uussiinngg specification if your file contains
   timedata.

   If the date format includes the day or month in words, the format
   string must exclude this text.  But it can still be printed with the
   "%a", "%A", "%b", or "%B" specifier.  ggnnuupplloott will determine the










   GNUPLOT 4.1                                                      208


   proper month and weekday from the numerical values.  See sseett ffoorrmmaatt
   for more details about these and other options for printing time
   data.

   When reading two-digit years with %y, values 69-99 refer to the 20th
   century, while values 00-68 refer to the 21st century.   NB: This is
   in accordance with the UNIX98 spec, but conventions vary widely and
   two-digit year values are inherently ambiguous.

   See also sseett xxddaattaa and TTiimmee//ddaattee for more information.

   Example:
         set timefmt "%d/%m/%Y\t%H:%M"
   tells ggnnuupplloott to read date and time separated by tab.  (But look
   closely at your data---what began as a tab may have been converted
   to spaces somewhere along the line; the format string must match
   what is actually in the file.)  See also time data demo.



        7788..7722..  TTiittllee


        The sseett ttiittllee command produces a plot title that is centered at
        the top of the plot.  sseett ttiittllee is a special case of sseett llaabbeell.

        Syntax:
              set title {"<title-text>"} {offset <offset>} {font
        "<font>{,<size>}"}
                        {{textcolor | tc} {<colorspec> | default}}
        {{no}enhanced}
              show title

        If <offset> is specified by either x,y or x,y,z the title is
        moved by the given offset.  It may be preceded by ffiirrsstt, sseecc--
        oonndd, ggrraapphh, ssccrreeeenn, or cchhaarraacctteerr to select the coordinate sys-
        tem.  See ccoooorrddiinnaatteess for details.  By default, the cchhaarraacctteerr
        coordinate system is used.  For example, "sseett ttiittllee ooffffsseett
        00,,--11" will change only the y offset of the title, moving the
        title down by roughly the height of one character.  The size of
        a character depends on both the font and the terminal.

        <font> is used to specify the font with which the title is to
        be written; the units of the font <size> depend upon which ter-
        minal is used.

        tteexxttccoolloorr <<ccoolloorrssppeecc>> changes the color of the text. <color-
        spec> can be a linetype, an rgb color, or a palette mapping.
        See help for ccoolloorrssppeecc and ppaalleettttee.

        nnooeennhhaanncceedd requests that the title not be processed by the
        enhanced text mode parser, even if enhanced text mode is cur-
        rently active.










   GNUPLOT 4.1                                                      209


        sseett ttiittllee with no parameters clears the title.

        See ssyynnttaaxx for details about the processing of backslash
        sequences and the distinction between single- and double-
        quotes.



        7788..7733..  TTmmaarrggiinn


        The command sseett ttmmaarrggiinn sets the size of the top margin.
        Please see sseett mmaarrggiinn for details.



        7788..7744..  TTrraannggee


        The sseett ttrraannggee command sets the parametric range used to com-
        pute x and y values when in parametric or polar modes.  Please
        see sseett xxrraannggee for details.



        7788..7755..  UUrraannggee


        The sseett uurraannggee and sseett vvrraannggee commands set the parametric
        ranges used to compute x, y, and z values when in sspplloott para-
        metric mode.  Please see sseett xxrraannggee for details.



        7788..7766..  VVaarriiaabblleess


        The sshhooww vvaarriiaabblleess command lists the current value of user-
        defined and internal variables. Gnuplot internally defines
        variables whose names begin with GPVAL_, MOUSE_, FIT_, and
        TERM_.

        Syntax:
              show variables      # show variables that do not begin
        with GPVAL_
              show variables all  # show all variables including those
        beginning GPVAL_
              show variables NAME # show only variables beginning with
        NAME














   GNUPLOT 4.1                                                      210


        7788..7777..  VVeerrssiioonn


        The sshhooww vveerrssiioonn command lists the version of gnuplot being
        run, its last modification date, the copyright holders, and
        email addresses for the FAQ, the gnuplot-info mailing list, and
        reporting bugs--in short, the information listed on the screen
        when the program is invoked interactively.

        Syntax:
              show version {long}

        When the lloonngg option is given, it also lists the operating sys-
        tem, the compilation options used when ggnnuupplloott was installed,
        the location of the help file, and (again) the useful email
        addresses.



        7788..7788..  VViieeww


        The sseett vviieeww command sets the viewing angle for ssppllootts.  It
        controls how the 3D coordinates of the plot are mapped into the
        2D screen space.  It provides controls for both rotation and
        scaling of the plotted data, but supports orthographic projec-
        tions only.  It supports both 3D projection or orthogonal 2D
        projection into a 2D plot-like map.

        Syntax:
              set view <rot_x>{,{<rot_z>}{,{<scale>}{,<scale_z>}}}
              set view map
              set view {no}equal {xy|xyz}
              show view

        where <rot_x> and <rot_z> control the rotation angles (in
        degrees) in a virtual 3D coordinate system aligned with the
        screen such that initially (that is, before the rotations are
        performed) the screen horizontal axis is x, screen vertical
        axis is y, and the axis perpendicular to the screen is z.  The
        first rotation applied is <rot_x> around the x axis.  The sec-
        ond rotation applied is <rot_z> around the new z axis.

        Command sseett vviieeww mmaapp is used to represent the drawing as a map.
        It can be used for ccoonnttoouurr plots, or for color ppmm33dd maps. In
        the latter, take care that you properly use zzrraannggee and ccbbrraannggee
        for input data point filtering and color range scaling, respec-
        tively.

        <rot_x> is bounded to the [0:180] range with a default of 60
        degrees, while <rot_z> is bounded to the [0:360] range with a
        default of 30 degrees.  <scale> controls the scaling of the
        entire sspplloott, while <scale_z> scales the z axis only.  Both










   GNUPLOT 4.1                                                      211


        scales default to 1.0.

        Examples:
              set view 60, 30, 1, 1
              set view ,,0.5

        The first sets all the four default values.  The second changes
        only scale, to 0.5.




             7788..7788..11..  EEqquuaall__aaxxeess


             The command sseett vviieeww eeqquuaall xxyy forces the unit length of
             the x and y axes to be on the same scale, and chooses that
             scale so that the plot will fit on the page.  The command
             sseett vviieeww eeqquuaall xxyyzz additionally sets the z axis scale to
             match the x and y axes; however there is no guarantee that
             the current z axis range will fit within the plot bound-
             ary.  By default all three axes are scaled independently
             to fill the available area.

             See also sseett xxyyppllaannee.



        7788..7799..  VVrraannggee


        The sseett uurraannggee and sseett vvrraannggee commands set the parametric
        ranges used to compute x, y, and z values when in sspplloott para-
        metric mode.  Please see sseett xxrraannggee for details.



        7788..8800..  XX22ddaattaa


        The sseett xx22ddaattaa command sets data on the x2 (top) axis to time-
        series (dates/times).  Please see sseett xxddaattaa.



        7788..8811..  XX22ddttiiccss


        The sseett xx22ddttiiccss command changes tics on the x2 (top) axis to
        days of the week.  Please see sseett xxddttiiccss for details.













   GNUPLOT 4.1                                                      212


        7788..8822..  XX22llaabbeell


        The sseett xx22llaabbeell command sets the label for the x2 (top) axis.
        Please see sseett xxllaabbeell.



        7788..8833..  XX22mmttiiccss


        The sseett xx22mmttiiccss command changes tics on the x2 (top) axis to
        months of the year.  Please see sseett xxmmttiiccss for details.



        7788..8844..  XX22rraannggee


        The sseett xx22rraannggee command sets the horizontal range that will be
        displayed on the x2 (top) axis.  Please see sseett xxrraannggee for
        details.



        7788..8855..  XX22ttiiccss


        The sseett xx22ttiiccss command controls major (labelled) tics on the x2
        (top) axis.  Please see sseett xxttiiccss for details.



        7788..8866..  XX22zzeerrooaaxxiiss


        The sseett xx22zzeerrooaaxxiiss command draws a line at the origin of the x2
        (top) axis (y2 = 0).  For details, please see sseett zzeerrooaaxxiiss.



        7788..8877..  XXddaattaa


        This command sets the datatype on the x axis to time/date.  A
        similar command does the same thing for each of the other axes.

        Syntax:
              set xdata {time}
              show xdata

        The same syntax applies to yyddaattaa, zzddaattaa, xx22ddaattaa, yy22ddaattaa and
        ccbbddaattaa.










   GNUPLOT 4.1                                                      213


        The ttiimmee option signals that the datatype is indeed time/date.
        If the option is not specified, the datatype reverts to normal.

        See sseett ttiimmeeffmmtt to tell gnuplot how to read date or time data.
        The time/date is converted to seconds from start of the cen-
        tury.  There is currently only one timefmt, which implies that
        all the time/date columns must conform to this format.  Speci-
        fication of ranges should be supplied as quoted strings accord-
        ing to this format to avoid interpretation of the time/date as
        an expression.

        The function 'strftime' (type "man strftime" on unix to look it
        up) is used to print tic-mark labels.  ggnnuupplloott tries to figure
        out a reasonable format for this  unless the sseett ffoorrmmaatt xx
        ""ssttrriinngg"" has supplied something that does not look like a deci-
        mal format (more than one '%' or neither %f nor %g).

        See also TTiimmee//ddaattee for more information.



        7788..8888..  XXddttiiccss


        The sseett xxddttiiccss commands converts the x-axis tic marks to days
        of the week where 0=Sun and 6=Sat.  Overflows are converted
        modulo 7 to dates.  sseett nnooxxddttiiccss returns the labels to their
        default values.  Similar commands do the same things for the
        other axes.

        Syntax:
              set xdtics
              unset xdtics
              show xdtics

        The same syntax applies to yyddttiiccss, zzddttiiccss, xx22ddttiiccss, yy22ddttiiccss and
        ccbbddttiiccss.

        See also the sseett ffoorrmmaatt command.



        7788..8899..  XXllaabbeell


        The sseett xxllaabbeell command sets the x axis label.  Similar commands
        set labels on the other axes.

        Syntax:
              set xlabel {"<label>"} {offset <offset>} {font
        "<font>{,<size>}"}
                         {{textcolor | tc} {lt <line_type> | default}}
        {{no}enhanced}










   GNUPLOT 4.1                                                      214


                         {rotate by <degrees>}
              show xlabel

        The same syntax applies to xx22llaabbeell, yyllaabbeell, yy22llaabbeell, zzllaabbeell and
        ccbbllaabbeell.

        If <offset> is specified by either x,y or x,y,z the label is
        moved by the given offset.  It may be preceded by ffiirrsstt, sseecc--
        oonndd, ggrraapphh, ssccrreeeenn, or cchhaarraacctteerr to select the coordinate sys-
        tem.  See ccoooorrddiinnaatteess for details.  By default, the cchhaarraacctteerr
        coordinate system is used.  For example, "sseett xxllaabbeell ooffffsseett
        --11,,00" will change only the x offset of the title, moving the
        label roughly one character width to the left.  The size of a
        character depends on both the font and the terminal.

        <font> is used to specify the font in which the label is writ-
        ten; the units of the font <size> depend upon which terminal is
        used.

        tteexxttccoolloorr lltt <<nn>> sets the text color to that of line type <n>.

        nnooeennhhaanncceedd requests that the label text not be processed by the
        enhanced text mode parser, even if enhanced text mode is cur-
        rently active.

        To clear a label, put no options on the command line, e.g.,
        "sseett yy22llaabbeell".

        The default positions of the axis labels are as follows:

        xlabel:  The x-axis label is centered below the bottom axis.

        ylabel:  The position of the y-axis label depends on the termi-
        nal, and can be one of the following three positions:

        1. Horizontal text flushed left at the top left of the plot.
        Terminals that cannot rotate text will probably use this
        method.  If sseett xx22ttiiccss is also in use, the ylabel may overwrite
        the left-most x2tic label.  This may be remedied by adjusting
        the ylabel position or the left margin.

        2. Vertical text centered vertically at the left of the plot.
        Terminals that can rotate text will probably use this method.

        3. Horizontal text centered vertically at the left of the plot.
        The EEPIC, LaTeX and TPIC drivers use this method.  The EEPIC
        driver will produce a stack of characters so as not to over-
        write the plot. With other drivers (such as LaTeX and TPIC),
        the user probably has to insert line breaks using \\ to prevent
        the ylabel from overwriting the plot.

        zlabel: The z-axis label is centered along the z axis and
        placed in the space above the grid level.










   GNUPLOT 4.1                                                      215


        cblabel: The color box axis label is centered along the box and
        placed below or right according to horizontal or vertical color
        box gradient.

        y2label: The y2-axis label is placed to the right of the y2
        axis.  The position is terminal-dependent in the same manner as
        is the y-axis label.

        x2label: The x2-axis label is placed above the top axis but
        below the plot title.  It is also possible to create an x2-axis
        label by using new-line characters to make a multi-line plot
        title, e.g.,

              set title "This is the title\n\nThis is the x2label"

        Note that double quotes must be used.  The same font will be
        used for both lines, of course.

        The orientation (rotation angle) of the x, x2, y and y2 axis
        labels can be explicitly changed from the default setting, but
        this applies only to 2D plots and only on terminals that sup-
        port text rotation.

        If you are not satisfied with the default position of an axis
        label, use sseett llaabbeell instead--that command gives you much more
        control over where text is placed.

        Please see ssyynnttaaxx for further information about backslash pro-
        cessing and the difference between single- and double-quoted
        strings.



        7788..9900..  XXmmttiiccss


        The sseett xxmmttiiccss command converts the x-axis tic marks to months
        of the year where 1=Jan and 12=Dec.  Overflows are converted
        modulo 12 to months.  The tics are returned to their default
        labels by uunnsseett xxmmttiiccss.  Similar commands perform the same
        duties for the other axes.

        Syntax:
              set xmtics
              unset xmtics
              show xmtics

        The same syntax applies to xx22mmttiiccss, yymmttiiccss, yy22mmttiiccss, zzmmttiiccss and
        ccbbmmttiiccss.

        See also the sseett ffoorrmmaatt command.












   GNUPLOT 4.1                                                      216


        7788..9911..  XXrraannggee


        The sseett xxrraannggee command sets the horizontal range that will be
        displayed.  A similar command exists for each of the other
        axes, as well as for the polar radius r and the parametric
        variables t, u, and v.

        Syntax:
              set xrange { [{{<min>}:{<max>}}] {{no}reverse}
        {{no}writeback} }
                         | restore
              show xrange

        where <min> and <max> terms are constants, expressions or an
        asterisk to set autoscaling.  If the data are time/date, you
        must give the range as a quoted string according to the sseett
        ttiimmeeffmmtt format.  Any value omitted will not be changed.

        The same syntax applies to yyrraannggee, zzrraannggee, xx22rraannggee, yy22rraannggee,
        ccbbrraannggee, rrrraannggee, ttrraannggee, uurraannggee and vvrraannggee.

        The rreevveerrssee option reverses the direction of the axis, e.g.,
        sseett xxrraannggee [[00::11]] rreevveerrssee will produce an axis with 1 on the
        left and 0 on the right.  This is identical to the axis pro-
        duced by sseett xxrraannggee [[11::00]], of course.  rreevveerrssee is intended pri-
        marily for use with aauuttoossccaallee.

        The wwrriitteebbaacckk option essentially saves the range found by
        aauuttoossccaallee in the buffers that would be filled by sseett xxrraannggee.
        This is useful if you wish to plot several functions together
        but have the range determined by only some of them.  The wwrriittee--
        bbaacckk operation is performed during the pplloott execution, so it
        must be specified before that command.  To restore, the last
        saved horizontal range use sseett xxrraannggee rreessttoorree.  For example,

              set xrange [-10:10]
              set yrange [] writeback
              plot sin(x)
              set yrange restore
              replot x/2

        results in a yrange of [-1:1] as found only from the range of
        sin(x); the [-5:5] range of x/2 is ignored.  Executing sshhooww
        yyrraannggee after each command in the above example should help you
        understand what is going on.

        In 2-d, xxrraannggee and yyrraannggee determine the extent of the axes,
        ttrraannggee determines the range of the parametric variable in para-
        metric mode or the range of the angle in polar mode.  Similarly
        in parametric 3-d, xxrraannggee, yyrraannggee, and zzrraannggee govern the axes
        and uurraannggee and vvrraannggee govern the parametric variables.











   GNUPLOT 4.1                                                      217


        In polar mode, rrrraannggee determines the radial range plotted.
        <rmin> acts as an additive constant to the radius, whereas
        <rmax> acts as a clip to the radius---no point with radius
        greater than <rmax> will be plotted.  xxrraannggee and yyrraannggee are
        affected---the ranges can be set as if the graph was of
        r(t)-rmin, with rmin added to all the labels.

        Any range may be partially or totally autoscaled, although it
        may not make sense to autoscale a parametric variable unless it
        is plotted with data.

        Ranges may also be specified on the pplloott command line.  A range
        given on the plot line will be used for that single pplloott com-
        mand; a range given by a sseett command will be used for all sub-
        sequent plots that do not specify their own ranges.  The same
        holds true for sspplloott.

        Examples:

        To set the xrange to the default:
              set xrange [-10:10]

        To set the yrange to increase downwards:
              set yrange [10:-10]

        To change zmax to 10 without affecting zmin (which may still be
        autoscaled):
              set zrange [:10]

        To autoscale xmin while leaving xmax unchanged:
              set xrange [*:]



        7788..9922..  XXttiiccss


        Fine control of the major (labelled) tics on the x axis is pos-
        sible with the sseett xxttiiccss command.  The tics may be turned off
        with the uunnsseett xxttiiccss command, and may be turned on (the default
        state) with sseett xxttiiccss.  Similar commands control the major tics
        on the y, z, x2 and y2 axes.

        Syntax:
              set xtics {axis | border} {{no}mirror}
                        {in | out} {scale {default | <major>
        {,<minor>}}}
                        {{no}rotate {by <ang>}} {offset <offset> |
        nooffset}
                        {add}
                        {  autofreq
                         | <incr>
                         | <start>, <incr> {,<end>}










   GNUPLOT 4.1                                                      218


                         | ({"<label>"} <pos> {<level>}
        {,{"<label>"}...) }
                        { format "formatstring" } { font
        "name{,<size>}" }
                        { rangelimited }
                        { textcolor <colorspec> }
              unset xtics
              show xtics

        The same syntax applies to yyttiiccss, zzttiiccss, xx22ttiiccss, yy22ttiiccss and
        ccbbttiiccss.

        aaxxiiss or bboorrddeerr tells ggnnuupplloott to put the tics (both the tics
        themselves and the accompanying labels) along the axis or the
        border, respectively.  If the axis is very close to the border,
        the aaxxiiss option will move the tic labels to outside the border.
        The relevant margin settings will usually be sized badly by the
        automatic layout algorithm in this case.

        mmiirrrroorr tells ggnnuupplloott to put unlabelled tics at the same posi-
        tions on the opposite border.  nnoommiirrrroorr does what you think it
        does.

        iinn and oouutt change the tic marks to be drawn inwards or out-
        wards.

        With ssccaallee, the size of the tic marks can be adjusted. If
        <minor> is not specified, it is 0.5*<major>.  The default size
        1.0 for major tics and 0.5 for minor tics is requested by ssccaallee
        ddeeffaauulltt.

        rroottaattee asks ggnnuupplloott to rotate the text through 90 degrees,
        which will be done if the terminal driver in use supports text
        rotation.  nnoorroottaattee cancels this. rroottaattee bbyy <<aanngg>> asks for
        rotation by <ang> degrees, supported by some terminal types.

        The defaults are bboorrddeerr mmiirrrroorr nnoorroottaattee for tics on the x and y
        axes, and bboorrddeerr nnoommiirrrroorr nnoorroottaattee for tics on the x2 and y2
        axes.  For the z axis, the {{aaxxiiss || bboorrddeerr}} option is not avail-
        able and the default is nnoommiirrrroorr.  If you do want to mirror the
        z-axis tics, you might want to create a bit more room for them
        with sseett bboorrddeerr.

        The <offset> is specified by either x,y or x,y,z, and may be
        preceded by ffiirrsstt, sseeccoonndd, ggrraapphh, ssccrreeeenn, or cchhaarraacctteerr to
        select the coordinate system. <offset> is the offset of the
        tics texts from their default positions, while the default
        coordinate system is cchhaarraacctteerr.  See ccoooorrddiinnaatteess for details.
        nnooooffffsseett switches off the offset.

        Example:

        Move xtics more closely to the plot.










   GNUPLOT 4.1                                                      219


              set xtics offset 0,graph 0.05

        sseett xxttiiccss with no options restores the default border or axis
        if xtics are being displayed;  otherwise it has no effect.  Any
        previously specified tic frequency or position {and labels} are
        retained.

        Positions of the tics are calculated automatically by default
        or if the aauuttooffrreeqq option is given; otherwise they may be spec-
        ified in either of two forms:

        The implicit <start>, <incr>, <end> form specifies that a
        series of tics will be plotted on the axis between the values
        <start> and <end> with an increment of <incr>.  If <end> is not
        given, it is assumed to be infinity.  The increment may be neg-
        ative.  If neither <start> nor <end> is given, <start> is
        assumed to be negative infinity, <end> is assumed to be posi-
        tive infinity, and the tics will be drawn at integral multiples
        of <incr>.  If the axis is logarithmic, the increment will be
        used as a multiplicative factor.

        If you specify to a negative <start> or <incr> after a numeri-
        cal value (e.g., rroottaattee bbyy <<aannggllee>> or ooffffsseett <<ooffffsseett>>), the
        parser fails because it subtracts <start> or <incr> from that
        value.  As a workaround, specify 00--<<ssttaarrtt>> resp. 00--<<iinnccrr>> in
        that case.

        Example:
              set xtics border offset 0,0.5 -5,1,5
        Fails with 'invalid expression' at the last comma.
              set xtics border offset 0,0.5 0-5,1,5
        or
              set xtics offset 0,0.5 border -5,1,5
        Sets tics at the border, tics text with an offset of 0,0.5
        characters, and sets the start, increment, and end to -5, 1,
        and 5, as requested.

        The sseett ggrriidd options 'front', 'back' and 'layerdefault' affect
        the drawing order of the xtics, too.

        Examples:

        Make tics at 0, 0.5, 1, 1.5, ..., 9.5, 10.
              set xtics 0,.5,10

        Make tics at ..., -10, -5, 0, 5, 10, ...
              set xtics 5

        Make tics at 1, 100, 1e4, 1e6, 1e8.
              set logscale x; set xtics 1,100,1e8

        The explicit ("<label>" <pos> <level>, ...) form allows arbi-
        trary tic positions or non-numeric tic labels.  In this form,










   GNUPLOT 4.1                                                      220


        the tics do not need to be listed in numerical order.  Each tic
        has a position, optionally with a label.  Note that the label
        is a string enclosed by quotes.  It may be a constant string,
        such as "hello", may contain formatting information for con-
        verting the position into its label, such as "%3f clients", or
        may be empty, "".  See sseett ffoorrmmaatt for more information.  If no
        string is given, the default label (numerical) is used.

        An explicit tic mark has a third parameter, the "level".  The
        default is level 0, a major tic.  A level of 1 generates a
        minor tic.  If the level is specified, then the label must also
        be supplied.

        Examples:
              set xtics ("low" 0, "medium" 50, "high" 100)
              set xtics (1,2,4,8,16,32,64,128,256,512,1024)
              set ytics ("bottom" 0, "" 10, "top" 20)
              set ytics ("bottom" 0, "" 10 1, "top" 20)

        In the second example, all tics are labelled.  In the third,
        only the end tics are labelled.  In the fourth, the unlabeled
        tic is a minor tic.

        Normally if explicit tics are given, they are used instead of
        auto-generated tics. Conversely if you specify sseett xxttiiccss aauuttoo
        or the like it will erase any previously specified explicit
        tics. You can mix explicit and auto- generated tics by using
        the keyword aadddd, which must appear before the tic style being
        added.

        Example:
              set xtics 0,.5,10
              set xtics add ("Pi" 3.14159)

        This will automatically generate tic marks every 0.5 along x,
        but will also add an explicit labeled tic mark at pi.

        However they are specified, tics will only be plotted when in
        range.

        Format (or omission) of the tic labels is controlled by sseett
        ffoorrmmaatt, unless the explicit text of a label is included in the
        sseett xxttiiccss ((""<<llaabbeell>>"")) form.

        Minor (unlabelled) tics can be added automatically by the sseett
        mmxxttiiccss command, or at explicit positions by the sseett xxttiiccss ((""""
        <<ppooss>> 11,, ......)) form.
















   GNUPLOT 4.1                                                      221


             7788..9922..11..  XXttiiccss ttiimmee__ddaattaa


             In case of timeseries data, axis tic position values must
             be given as quoted dates or times according to the format
             ttiimmeeffmmtt. If the <start>, <incr>, <end> form is used,
             <start> and <end> must be given according to ttiimmeeffmmtt, but
             <incr> must be in seconds.  Times will be written out
             according to the format given on sseett ffoorrmmaatt, however.

             Examples:
                   set xdata time
                   set timefmt "%d/%m"
                   set xtics format "%b %d"
                   set xrange ["01/12":"06/12"]
                   set xtics "01/12", 172800, "05/12"

                   set xdata time
                   set timefmt "%d/%m"
                   set xtics format "%b %d"
                   set xrange ["01/12":"06/12"]
                   set xtics ("01/12", "" "03/12", "05/12")
             Both of these will produce tics "Dec 1", "Dec 3", and "Dec
             5", but in the second example the tic at "Dec 3" will be
             unlabelled.



             7788..9922..22..  XXttiiccss rraannggeelliimmiitteedd


             This option limits both the auto-generated axis tic labels
             and the corresponding plot border to the range of values
             actually present in the data that has been plotted.  Note
             that this is independent of the current range limits for
             the plot. For example, suppose that the data in "file.dat"
             all lies in the range 2 < y < 4.  Then the following com-
             mands will create a plot for which the left-hand plot bor-
             der (y axis) is drawn for only this portion of the total y
             range, and only the axis tics in this region are gener-
             ated.  I.e., the plot will be scaled to the full range on
             y, but there will be a gap between 0 and 2 on the left
             border and another gap between 4 and 10. This style is
             sometimes refered to as a rraannggee--ffrraammee graph.
                   set border 3
                   set yrange [0:10]
                   set ytics nomirror rangelimited
                   plot "file.dat"















   GNUPLOT 4.1                                                      222


        7788..9933..  XXyyppllaannee


        The sseett xxyyppllaannee command adjusts the position at which the xy
        plane is drawn in a 3D plot.  The synonym "set ticslevel" is
        accepted for backwards compatibility.

        Syntax:
              set xyplane at <zvalue>
              set xyplane relative <frac>
              set ticslevel <frac>        # equivalent to set xyplane
        relative
              show xyplane

        The form sseett xxyyppllaannee rreellaattiivvee <<ffrraacc>> places the xy plane below
        the range in Z, where the distance from the xy plane to Zmin is
        given as a fraction of the total range in z.  The default value
        is 0.5.  Negative values are permitted, but tic labels on the
        three axes may overlap.  The older, deprecated, form sseett ttiicc--
        sslleevveell is retained for backwards compatibility.

        To place the xy-plane at a position 'pos' on the z-axis, ttiicc--
        sslleevveell may be set equal to  (pos - zmin) / (zmin - zmax).  How-
        ever, this position will change if the z range is changed.

        The alternative form sseett xxyyppllaannee aatt <<zzvvaalluuee>> fixes the place-
        ment of the xy plane at a specific Z value regardless of the
        current z range. Thus to force the x, y, and z axes to meet at
        a common origin one would specify sseett xxyyppllaannee aatt 00.

        See also sseett vviieeww, and sseett zzeerrooaaxxiiss.



        7788..9944..  XXzzeerrooaaxxiiss


        The sseett xxzzeerrooaaxxiiss command draws a line at y = 0.  For details,
        please see sseett zzeerrooaaxxiiss.



        7788..9955..  YY22ddaattaa


        The sseett yy22ddaattaa command sets y2 (right-hand) axis data to time-
        series (dates/times).  Please see sseett xxddaattaa.
















   GNUPLOT 4.1                                                      223


        7788..9966..  YY22ddttiiccss


        The sseett yy22ddttiiccss command changes tics on the y2 (right-hand)
        axis to days of the week.  Please see sseett xxddttiiccss for details.



        7788..9977..  YY22llaabbeell


        The sseett yy22llaabbeell command sets the label for the y2 (right-hand)
        axis.  Please see sseett xxllaabbeell.



        7788..9988..  YY22mmttiiccss


        The sseett yy22mmttiiccss command changes tics on the y2 (right-hand)
        axis to months of the year.  Please see sseett xxmmttiiccss for details.



        7788..9999..  YY22rraannggee


        The sseett yy22rraannggee command sets the vertical range that will be
        displayed on the y2 (right-hand) axis.  Please see sseett xxrraannggee
        for details.



        7788..110000..  YY22ttiiccss


        The sseett yy22ttiiccss command controls major (labelled) tics on the y2
        (right-hand) axis.  Please see sseett xxttiiccss for details.



        7788..110011..  YY22zzeerrooaaxxiiss


        The sseett yy22zzeerrooaaxxiiss command draws a line at the origin of the y2
        (right-hand) axis (x2 = 0).  For details, please see sseett
        zzeerrooaaxxiiss.
















   GNUPLOT 4.1                                                      224


        7788..110022..  YYddaattaa


        The sseett yyddaattaa commands sets y-axis data to timeseries
        (dates/times).  Please see sseett xxddaattaa.



        7788..110033..  YYddttiiccss


        The sseett yyddttiiccss command changes tics on the y axis to days of
        the week.  Please see sseett xxddttiiccss for details.



        7788..110044..  YYllaabbeell


        This command sets the label for the y axis.  Please see sseett
        xxllaabbeell.



        7788..110055..  YYmmttiiccss


        The sseett yymmttiiccss command changes tics on the y axis to months of
        the year.  Please see sseett xxmmttiiccss for details.



        7788..110066..  YYrraannggee


        The sseett yyrraannggee command sets the vertical range that will be
        displayed on the y axis.  Please see sseett xxrraannggee for details.



        7788..110077..  YYttiiccss


        The sseett yyttiiccss command controls major (labelled) tics on the y
        axis.  Please see sseett xxttiiccss for details.



        7788..110088..  YYzzeerrooaaxxiiss


        The sseett yyzzeerrooaaxxiiss command draws a line at x = 0.  For details,
        please see sseett zzeerrooaaxxiiss.










   GNUPLOT 4.1                                                      225


        7788..110099..  ZZddaattaa


        The sseett zzddaattaa command sets zaxis data to timeseries
        (dates/times).  Please see sseett xxddaattaa.



        7788..111100..  ZZddttiiccss


        The sseett zzddttiiccss command changes tics on the z axis to days of
        the week.  Please see sseett xxddttiiccss for details.



        7788..111111..  ZZzzeerrooaaxxiiss


        The sseett zzzzeerrooaaxxiiss command draws a line through (x=0,y=0).  This
        has no effect on 2D plots, including splot with sseett vviieeww mmaapp.
        For details, please see sseett zzeerrooaaxxiiss and sseett xxyyppllaannee.



        7788..111122..  CCbbddaattaa


        Set color box axis data to timeseries (dates/times).  Please
        see sseett xxddaattaa.



        7788..111133..  CCbbddttiiccss


        The sseett ccbbddttiiccss command changes tics on the color box axis to
        days of the week. Please see sseett xxddttiiccss for details.



        7788..111144..  ZZeerroo


        The zzeerroo value is the default threshold for values approaching
        0.0.

        Syntax:
              set zero <expression>
              show zero

        ggnnuupplloott will not plot a point if its imaginary part is greater
        in magnitude than the zzeerroo threshold.  This threshold is also










   GNUPLOT 4.1                                                      226


        used in various other parts of ggnnuupplloott as a (crude) numerical-
        error threshold.  The default zzeerroo value is 1e-8.  zzeerroo values
        larger than 1e-3 (the reciprocal of the number of pixels in a
        typical bitmap display) should probably be avoided, but it is
        not unreasonable to set zzeerroo to 0.0.



        7788..111155..  ZZeerrooaaxxiiss


        The x axis may be drawn by sseett xxzzeerrooaaxxiiss and removed by uunnsseett
        xxzzeerrooaaxxiiss.  Similar commands behave similarly for the y, x2,
        y2, and z axes.

        Syntax:
              set {x|x2|y|y2|z}zeroaxis { {linestyle | ls <line_style>}
                                         | { linetype | lt <line_type>}
                                           { linewidth | lw
        <line_width>}}
              unset {x|x2|y|y2|z}zeroaxis
              show {x|y|z}zeroaxis


        By default, these options are off.  The selected zero axis is
        drawn with a line of type <line_type> and width <line_width>
        (if supported by the terminal driver currently in use), or a
        user-defined style <line_style>.

        If no linetype is specified, any zero axes selected will be
        drawn using the axis linetype (linetype 0).

        sseett zzeerrooaaxxiiss is equivalent to sseett xxzzeerrooaaxxiiss;; sseett yyzzeerrooaaxxiiss.
        Note that the z-axis must be set separately using sseett zzzzee--
        rrooaaxxiiss.

        Examples:

        To simply have the y=0 axis drawn visibly:

               set xzeroaxis

        If you want a thick line in a different color or pattern,
        instead:

               set xzeroaxis linetype 3 linewidth 2.5



        7788..111166..  ZZllaabbeell













   GNUPLOT 4.1                                                      227


        This command sets the label for the z axis.  Please see sseett
        xxllaabbeell.



        7788..111177..  ZZmmttiiccss


        The sseett zzmmttiiccss command changes tics on the z axis to months of
        the year.  Please see sseett xxmmttiiccss for details.



        7788..111188..  ZZrraannggee


        The sseett zzrraannggee command sets the range that will be displayed on
        the z axis.  The zrange is used only by sspplloott and is ignored by
        pplloott.  Please see sseett xxrraannggee for details.



        7788..111199..  ZZttiiccss


        The sseett zzttiiccss command controls major (labelled) tics on the z
        axis.  Please see sseett xxttiiccss for details.



        7788..112200..  CCbbllaabbeell


        This command sets the label for the color box axis.  Please see
        sseett xxllaabbeell.



        7788..112211..  CCbbmmttiiccss


        The sseett ccbbmmttiiccss command changes tics on the color box axis to
        months of the year. Please see sseett xxmmttiiccss for details.



        7788..112222..  CCbbrraannggee


        The sseett ccbbrraannggee command sets the range of values which are col-
        ored using the current ppaalleettttee by styles wwiitthh ppmm33dd, wwiitthh iimmaaggee
        and wwiitthh ppaalleettttee.  Values outside of the color range use color
        of the nearest extreme.










   GNUPLOT 4.1                                                      228


        If the cb-axis is autoscaled in sspplloott, then the colorbox range
        is taken from zzrraannggee.  Points drawn in sspplloott ...... ppmm33dd||ppaalleettttee
        can be filtered by using different zzrraannggee and ccbbrraannggee.

        Please see sseett xxrraannggee for details on sseett ccbbrraannggee syntax. See
        also sseett ppaalleettttee and sseett ccoolloorrbbooxx.



        7788..112233..  CCbbttiiccss


        The sseett ccbbttiiccss command controls major (labelled) tics on the
        color box axis.  Please see sseett xxttiiccss for details.



   7799..  SShheellll


   The sshheellll command spawns an interactive shell.  To return to ggnnuu--
   pplloott, type llooggoouutt if using VMS, eexxiitt or the END-OF-FILE character if
   using Unix, eennddccllii if using AmigaOS, or eexxiitt if using MS-DOS or
   OS/2.

   There are two ways of spawning a shell command: using ssyysstteemm command
   or via !! ($ if using VMS). The former command takes a string as a
   parameter and thus it can be used anywhere among other gnuplot com-
   mands, while the latter syntax requires to be the only command on
   the line. Control will return immediately to ggnnuupplloott after this com-
   mand is executed.  For example, in AmigaOS, MS-DOS or OS/2,

         ! dir
   or
         system "dir"

   prints a directory listing and then returns to ggnnuupplloott.

   Other examples of the former syntax:
          system "date"; set time; plot "a.dat"
          print=1; if (print) replot; set out; system "lpr x.ps"



   8800..  SSpplloott


   sspplloott is the command for drawing 3D plots (well, actually projec-
   tions on a 2D surface, but you knew that).  It can create a plot
   from functions or data read from files in a manner very similar to
   the pplloott command.  sspplloott provides only a single x, y, and z axis;
   there is no equivalent to the x2 and y2 secondary axes provided by
   pplloott.










   GNUPLOT 4.1                                                      229


   See pplloott for features common to the pplloott command; only differences
   are discussed in detail here.

   Syntax:
         splot {<ranges>}
               {<iteration>}
               <function> | "<datafile>" {datafile-modifiers}}
               {<title-spec>} {with <style>}
               {, {definitions{,}} <function> ...}

   where either a <function> or the name of a data file enclosed in
   quotes is supplied.  The function can be a mathematical expression,
   or a triple of mathematical expressions in parametric mode.

   By default sspplloott draws the xy plane completely below the plotted
   data.  The offset between the lowest ztic and the xy plane can be
   changed by sseett xxyyppllaannee.  The orientation of a sspplloott projection is
   controlled by sseett vviieeww.  See sseett vviieeww and sseett xxyyppllaannee for more
   information.

   The syntax for setting ranges on the sspplloott command is the same as
   for pplloott.  In non-parametric mode, the order in which ranges must be
   given is xxrraannggee, yyrraannggee, and zzrraannggee.  In parametric mode, the order
   is uurraannggee, vvrraannggee, xxrraannggee, yyrraannggee, and zzrraannggee.

   The ttiittllee option is the same as in pplloott.  The operation of wwiitthh is
   also the same as in pplloott, except that the plotting styles available
   to sspplloott are limited to lliinneess, ppooiinnttss, lliinneessppooiinnttss, ddoottss, and
   iimmppuullsseess;  the error-bar capabilities of pplloott are not available for
   sspplloott.

   The ddaattaaffiillee options have more differences.

   See also sshhooww pplloott.




        8800..11..  DDaattaa--ffiillee


        As for pplloott, discrete data contained in a file can be displayed
        by specifying the name of the data file, enclosed in quotes,
        on the sspplloott command line.

        Syntax:
              splot '<file_name>' {binary <binary list>}
                                  {{nonuniform} matrix}
                                  {index <index list>}
                                  {every <every list>}
                                  {using <using list>}

        The special filenames """" and ""--"" are permitted, as in pplloott.










   GNUPLOT 4.1                                                      230


        In brief, bbiinnaarryy and mmaattrriixx indicate that the data are in a
        special form, iinnddeexx selects which data sets in a multi-data-set
        file are to be plotted, eevveerryy specifies which datalines (sub-
        sets) within a single data set are to be plotted, and uussiinngg
        determines how the columns within a single record are to be
        interpreted.

        The options iinnddeexx and eevveerryy behave the same way as with pplloott;
        uussiinngg does so also, except that the uussiinngg list must provide
        three entries instead of two.

        The pplloott options tthhrruu and ssmmooootthh are not available for sspplloott,
        but ccnnttrrppaarraamm and ddggrriidd33dd provide limited smoothing capabili-
        ties.

        Data file organization is essentially the same as for pplloott,
        except that each point is an (x,y,z) triple.  If only a single
        value is provided, it will be used for z, the datablock number
        will be used for y, and the index of the data point in the dat-
        ablock will be used for x.  If two or four values are provided,
        ggnnuupplloott uses the last value for calculating the color in pm3d
        plots.  Three values are interpreted as an (x,y,z) triple.
        Additional values are generally used as errors, which can be
        used by ffiitt.

        Single blank records separate datablocks in a sspplloott datafile;
        sspplloott treats datablocks as the equivalent of function y-iso-
        lines.  No line will join points separated by a blank record.
        If all datablocks contain the same number of points, ggnnuupplloott
        will draw cross-isolines between datablocks, connecting corre-
        sponding points.  This is termed "grid data", and is required
        for drawing a surface, for contouring (sseett ccoonnttoouurr) and hidden-
        line removal (sseett hhiiddddeenn33dd). See also sspplloott ggrriidd__ddaattaa.

        It is no longer necessary to specify ppaarraammeettrriicc mode for three-
        column ssppllootts.




             8800..11..11..  BBiinnaarryy mmaattrriixx


             Gnuplot can read matrix binary files by use of the option
             bbiinnaarryy appearing without keyword qualifications unique to
             general binary, i.e., aarrrraayy, rreeccoorrdd, ffoorrmmaatt, or ffiilleettyyppee.
             Other general binary keywords for translation should also
             apply to matrix binary.  (See bbiinnaarryy ggeenneerraall for more
             details.)

             In previous versions, ggnnuupplloott dynamically detected binary
             data files.  It is now necessary to specify the keyword
             bbiinnaarryy directly after the filename.










   GNUPLOT 4.1                                                      231


             Single precision floats are stored in a binary file as
             follows:

                   <N+1>  <y0>   <y1>   <y2>  ...  <yN>
                    <x0> <z0,0> <z0,1> <z0,2> ... <z0,N>
                    <x1> <z1,0> <z1,1> <z1,2> ... <z1,N>
                     :      :      :      :   ...    :

             which are converted into triplets:
                   <x0> <y0> <z0,0>
                   <x0> <y1> <z0,1>
                   <x0> <y2> <z0,2>
                    :    :     :
                   <x0> <yN> <z0,N>

                   <x1> <y0> <z1,0>
                   <x1> <y1> <z1,1>
                    :    :     :

             These triplets are then converted into ggnnuupplloott iso-curves
             and then ggnnuupplloott proceeds in the usual manner to do the
             rest of the plotting.

             A collection of matrix and vector manipulation routines
             (in C) is provided in bbiinnaarryy..cc.  The routine to write
             binary data is

                   int
             fwrite_matrix(file,m,nrl,nrl,ncl,nch,row_title,col-
             umn_title)

             An example of using these routines is provided in the file
             bbff__tteesstt..cc, which generates binary files for the demo file
             ddeemmoo//bbiinnaarryy..ddeemm.

             The iinnddeexx keyword is not supported, since the file format
             allows only one surface per file.  The eevveerryy and uussiinngg
             filters are supported.  uussiinngg operates as if the data were
             read in the above triplet form.

             See also bbiinnaarryy ggeenneerraall and

             Binary File Splot Demo.



             8800..11..22..  EExxaammppllee ddaattaaffiillee


             A simple example of plotting a 3D data file is

                   splot 'datafile.dat'











   GNUPLOT 4.1                                                      232


             where the file "datafile.dat" might contain:

                   # The valley of the Gnu.
                      0 0 10
                      0 1 10
                      0 2 10

                      1 0 10
                      1 1 5
                      1 2 10

                      2 0 10
                      2 1 1
                      2 2 10

                      3 0 10
                      3 1 0
                      3 2 10

             Note that "datafile.dat" defines a 4 by 3 grid ( 4 rows of
             3 points each ).  Rows (datablocks) are separated by blank
             records.

             Note also that the x value is held constant within each
             dataline.  If you instead keep y constant, and plot with
             hidden-line removal enabled, you will find that the sur-
             face is drawn 'inside-out'.

             Actually for grid data it is not necessary to keep the x
             values constant within a datablock, nor is it necessary to
             keep the same sequence of y values.  ggnnuupplloott requires only
             that the number of points be the same for each datablock.
             However since the surface mesh, from which contours are
             derived, connects sequentially corresponding points, the
             effect of an irregular grid on a surface plot is unpre-
             dictable and should be examined on a case-by-case basis.



             8800..11..33..  MMaattrriixx__aasscciiii


             The mmaattrriixx keyword (without a sequent bbiinnaarryy keyword) in
                 {s}plot 'a.dat' matrix
             indicates that data are stored in an ascii numbers matrix
             format.

             The z-values are read in a row at a time, i. e.,
                 z11 z12 z13 z14 ...
                 z21 z22 z23 z24 ...
                 z31 z32 z33 z34 ...
             and so forth.











   GNUPLOT 4.1                                                      233


             In 3D, the x- and y-indices of the matrix surface plot
             correspond to column and row indices of the matrix,
             respectively, being enumerated from 0. You can rescale or
             transform the axes as usual for a data file with three
             columns by means of x=$1, y=$2, z=$3. For example
                 splot 'a.dat' matrix using (1+$1/100):(1+$2*10):3

             A blank line or comment line ends the matrix, and starts a
             new surface mesh.  You can select among the meshes inside
             a file by the iinnddeexx option to the sspplloott command, as usual.

             See mmaattrriixx for examples of plotting rows and columns of
             the matrix in a 2D plot.



             8800..11..44..  MMaattrriixx


             Datafile can be in an ascii or binary matrix format. The
             mmaattrriixx flag indicates that the file is ascii, the bbiinnaarryy
             or mmaattrriixx bbiinnaarryy stands for a binary format. For details,
             see mmaattrriixx aasscciiii and mmaattrriixx bbiinnaarryy.

             Basic usage in sspplloott:
                 splot 'a.dat' matrix
                 splot 'a.gpbin' {matrix} binary
             Advanced usage in sspplloott:
                 splot 'a.dat' matrix using 1:2:3
                 splot 'a.gpbin' {matrix} binary using 1:2:3
             allows to transform the axes coordinates and the z-data
             independently.

             Usage in pplloott:
                 plot `a.dat` matrix
                 plot `a.dat` matrix using 1:3
                 plot 'a.gpbin' {matrix} binary using 1:3
             will plot rows of the matrix, while using 2:3 will plot
             matrix columns, and using 1:2 the point coordinates
             (rather useless). Applying the eevveerryy option you can spec-
             ify explicit rows and columns.

             Example -- rescale axes of a matrix in an ascii file:
                 splot `a.dat` matrix using (1+$1):(1+$2*10):3

             Example -- plot the 3rd row of a matrix in an ascii file:
                 plot 'a.dat' matrix using 1:3 every 1:999:1:2
             (rows are enumerated from 0, thus 2 instead of 3).















   GNUPLOT 4.1                                                      234


        8800..22..  GGrriidd ddaattaa


        The 3D routines are designed for points in a grid format, with
        one sample, datapoint, at each mesh intersection; the data-
        points may originate from either evaluating a function, see sseett
        iissoossaammpplleess, or reading a datafile, see sspplloott ddaattaaffiillee.  The
        term "isoline" is applied to the mesh lines for both functions
        and data.  Note that the mesh need not be rectangular in x and
        y, as it may be parameterized in u and v, see sseett iissoossaammpplleess.

        However, ggnnuupplloott does not require that format.  In the case of
        functions, 'samples' need not be equal to 'isosamples', i.e.,
        not every x-isoline sample need intersect a y-isoline. In the
        case of data files, if there are an equal number of scattered
        data points in each datablock, then "isolines" will connect the
        points in a datablock, and "cross-isolines" will connect the
        corresponding points in each datablock to generate a "surface".
        In either case, contour and hidden3d modes may give different
        plots than if the points were in the intended format.  Scat-
        tered data can be converted to a {different} grid format with
        sseett ddggrriidd33dd.

        The contour code tests for z intensity along a line between a
        point on a y-isoline and the corresponding point in the next y-
        isoline.  Thus a sspplloott contour of a surface with samples on the
        x-isolines that do not coincide with a y-isoline intersection
        will ignore such samples. Try:
               set xrange [-pi/2:pi/2]; set yrange [-pi/2:pi/2]
               set style function lp
               set contour
               set isosamples 10,10; set samples 10,10;
               splot cos(x)*cos(y)
               set samples 4,10; replot
               set samples 10,4; replot




        8800..33..  SSpplloott oovveerrvviieeww


        sspplloott can display a surface as a collection of points, or by
        connecting those points.  As with pplloott, the points may be read
        from a data file or result from evaluation of a function at
        specified intervals, see sseett iissoossaammpplleess.  The surface may be
        approximated by connecting the points with straight line seg-
        ments, see sseett ssuurrffaaccee, in which case the surface can be made
        opaque with sseett hhiiddddeenn33dd..  The orientation from which the 3d
        surface is viewed can be changed with sseett vviieeww.

        Additionally, for points in a grid format, sspplloott can interpo-
        late points having a common amplitude (see sseett ccoonnttoouurr) and can










   GNUPLOT 4.1                                                      235


        then connect those new points to display contour lines, either
        directly with straight-line segments or smoothed lines (see sseett
        ccnnttrrppaarraamm).  Functions are already evaluated in a grid format,
        determined by sseett iissoossaammpplleess and sseett ssaammpplleess, while file data
        must either be in a grid format, as described in ddaattaa--ffiillee, or
        be used to generate a grid (see sseett ddggrriidd33dd).

        Contour lines may be displayed either on the surface or pro-
        jected onto the base.  The base projections of the contour
        lines may be written to a file, and then read with pplloott, to
        take advantage of pplloott's additional formatting capabilities.



   8811..  SSyysstteemm


   ssyysstteemm ""ccoommmmaanndd"" executes "command" using the standard shell. See
   sshheellll.  If called as a function, ssyysstteemm((""ccoommmmaanndd"")) returns the
   resulting character stream from stdout as a string.  One optional
   trailing newline is ignored.

   This can be used to import external functions into gnuplot scripts:

         f(x) = real(system(sprintf("somecommand %f", x)))



   8822..  TTeesstt


   This command graphically tests or presents terminal and palette
   capabilities.

   Syntax:
         test {terminal | palette [rgb|rbg|grb|gbr|brg|bgr]}

   tteesstt or tteesstt tteerrmmiinnaall creates a display of line and point styles and
   other useful things appropriate for and supported by the tteerrmmiinnaall
   you are just using.

   tteesstt ppaalleettttee draws graphically profiles R(z),G(z),B(z), where
   0<=z<=1, as calculated by the current color ppaalleettttee. In other words,
   it is a beautiful plot you would have to construct from the result
   of sshhooww ppaalleettttee ppaalleettttee 225566 ffllooaatt.  The optional parameter, a permu-
   tation of letters rgb, determines the sequence of r,g,b profiles
   drawn one after the other --- try this yourself for sseett ppaalleettttee
   ggrraayy. The default sequence is rgb.















   GNUPLOT 4.1                                                      236


   8833..  UUnnddeeffiinnee


   Clear one or more previously defined user variables.  This is useful
   in order to reset the state of a script containing an initialization
   test.

   Example:

         undefine foo foo1 foo2
         if (!exists("foo")) load "initialize.gp"




   8844..  UUnnsseett


   Options set using the sseett command may be returned to their default
   state by the corresponding uunnsseett command.  The uunnsseett command may
   contain an optional iteration clause. See iitteerraattiioonn.

   Examples:
         set xtics mirror rotate by -45 0,10,100
         ...
         unset xtics

         # Unset labels numbered between 100 and 200
         unset for [i=100:200] label i




   8855..  UUppddaattee


   This command writes the current values of the fit parameters into
   the given file, formatted as an initial-value file (as described in
   the ffiittsection).  This is useful for saving the current values for
   later use or for restarting a converged or stopped fit.

   Syntax:
         update <filename> {<filename>}

   If a second filename is supplied, the updated values are written to
   this file, and the original parameter file is left unmodified.

   Otherwise, if the file already exists, ggnnuupplloott first renames it by
   appending ..oolldd and then opens a new file.  That is, "uuppddaattee ''ffrreedd''"
   behaves the same as "!!rreennaammee ffrreedd ffrreedd..oolldd;; uuppddaattee ''ffrreedd..oolldd''
   ''ffrreedd''".  [On DOS and other systems that use the twelve-character
   "filename.ext" naming convention, "ext" will be "oolldd" and "filename"
   will be related (hopefully recognizably) to the initial name.










   GNUPLOT 4.1                                                      237


   Renaming is not done at all on VMS systems, since they use file-ver-
   sioning.]

   Please see ffiitt for more information.




   8866..  TTeerrmmiinnaall ttyyppeess





   8877..  CCoommpplleettee lliisstt ooff tteerrmmiinnaallss


   Gnuplot supports a large number of output formats. These are
   selected by choosing an appropriate terminal type, possibly with
   additional modifying options. See sseett tteerrmmiinnaall.

   This document may describe terminal types that are not available to
   you because they were not configured or installed on your system. To
   see a list of terminals available on a particular gnuplot installa-
   tion, type 'set terminal' with no modifiers.





        8877..11..  AAeedd776677


        The aaeedd551122 and aaeedd776677 terminal drivers support AED graphics
        terminals.  The two drivers differ only in their horizontal
        ranges, which are 512 and 768 pixels, respectively.  Their ver-
        tical range is 575 pixels.  There are no options for these
        drivers.



        8877..22..  AAiiffmm



        NOTE: this terminal driver is outdated. Since Adobe Illustrator
        understands PostScript level 1 directly, you should use sseett
        tteerrmmiinnaall ppoosstt lleevveell11 instead.

        Several options may be set in aaiiffmm---the Adobe Illustrator 3.0+
        driver.

        Syntax:










   GNUPLOT 4.1                                                      238


              set terminal aifm {<color>} {"<fontname>"} {<fontsize>}

        <color> is either ccoolloorr or mmoonnoocchhrroommee; "<fontname>" is the name
        of a valid PostScript font; <fontsize> is the size of the font
        in PostScript points, before scaling by the sseett ssiizzee command.
        Selecting ddeeffaauulltt sets all options to their default values:
        mmoonnoocchhrroommee, "Times-Roman", and 14pt.

        Since AI does not really support multiple pages, multiple
        graphs will be drawn directly on top of one another.  However,
        each graph will be grouped individually, making it easy to sep-
        arate them inside AI (just pick them up and move them).

        Examples:
              set term aifm
              set term aifm 22
              set size 0.7,1.4; set term aifm color "Times-Roman" 14



        8877..33..  AAmmiiggaa


        The aammiiggaa terminal, for Commodore Amiga computers, allows the
        user to plot either to a screen (default), or, if Kickstart 3.0
        or higher is installed, to a window on the current public
        screen. The font and its size can also be selected.

        Syntax:
              set terminal amiga {screen | window} {"<fontname>"}
        {<fontsize>}

        The default font is 8-point "topaz".

        The screen option uses a virtual screen, so it is possible that
        the graph will be larger than the screen.



        8877..44..  AAppoolllloo


        The aappoolllloo terminal driver supports the Apollo Graphics Primi-
        tive Resource with rescaling after window resizing.  It has no
        options.

        If a fixed-size window is desired, the ggpprr terminal may be used
        instead.















   GNUPLOT 4.1                                                      239


        8877..55..  AAqquuaa


        This terminal relies on AquaTerm.app for display on Mac OS X.

        Syntax:
              set terminal aqua {<n>} {title "<wintitle>"} {size <x>
        <y>}
                                {font "<fontname>{,<fontsize>}"}
                                {{no}enhanced} {solid|dashed} {dl
        <dashlength>}}

        where <n> is the number of the window to draw in (default is
        0), <wintitle> is the name shown in the title bar (default
        "Figure <n>"), <x> <y> is the size of the plot (default is
        846x594 pt = 11.75x8.25 in).

        Use <fontname> to specify the font to use (default is "Times-
        Roman"), and <fontsize> to specify the font size (default is
        14.0 pt). The old syntax {fname "<fontname>"} {fsize <font-
        size>} is still supported.

        The aqua terminal supports enhanced text mode (see eennhhaanncceedd),
        except for overprint. Font support is limited to the fonts
        available on the system.  Character encoding can be selected by
        sseett eennccooddiinngg and currently supports iso_latin_1, iso_latin_2,
        cp1250, and default which equals UTF8.

        Lines can be drawn either solid or dashed, (default is solid)
        and the dash spacing can be modified by <dashlength> which is a
        multiplier > 0.




        8877..66..  BBee


        ggnnuupplloott provides the bbee terminal type for use with X servers.
        This terminal type is set automatically at startup if the DDIISS--
        PPLLAAYY environment variable is set, if the TTEERRMM environment vari-
        able is set to xxtteerrmm, or if the --ddiissppllaayy command line option is
        used.

        Syntax:
                  set terminal be {reset} {<n>}

        Multiple plot windows are supported: sseett tteerrmmiinnaall bbee <<nn>>
        directs the output to plot window number n.  If n>0, the termi-
        nal number will be appended to the window title and the icon
        will be labeled ggpplltt <<nn>>.  The active window may distinguished
        by a change in cursor (from default to crosshair.)











   GNUPLOT 4.1                                                      240


        Plot windows remain open even when the ggnnuupplloott driver is
        changed to a different device.  A plot window can be closed by
        pressing the letter q while that window has input focus, or by
        choosing cclloossee from a window manager menu.  All plot windows
        can be closed by specifying rreesseett, which actually terminates
        the subprocess which maintains the windows (unless --ppeerrssiisstt was
        specified).

        Plot windows will automatically be closed at the end of the
        session unless the --ppeerrssiisstt option was given.

        The size or aspect ratio of a plot may be changed by resizing
        the ggnnuupplloott window.

        Linewidths and pointsizes may be changed from within ggnnuupplloott
        with sseett lliinneessttyyllee.

        For terminal type bbee, ggnnuupplloott accepts (when initialized) the
        standard X Toolkit options and resources such as geometry,
        font, and name from the command line arguments or a configura-
        tion file.  See the X(1) man page (or its equivalent) for a
        description of such options.

        A number of other ggnnuupplloott options are available for the bbee ter-
        minal.  These may be specified either as command-line options
        when ggnnuupplloott is invoked or as resources in the configuration
        file ".Xdefaults".  They are set upon initialization and cannot
        be altered during a ggnnuupplloott session.




             8877..66..11..  CCoommmmaanndd--lliinnee__ooppttiioonnss


             In addition to the X Toolkit options, the following
             options may be specified on the command line when starting
             ggnnuupplloott or as resources in your ".Xdefaults" file:



   +---------------------------------------------------------------------------------+
   |    `-mono`        forces monochrome rendering on color displays.                |
   |    `-gray`        requests grayscale rendering on grayscale or color displays.  |
   |                   (Grayscale displays receive monochrome rendering by default.) |
   |    `-clear`       requests that the window be cleared momentarily before a      |
   |                   new plot is displayed.                                        |
   |    `-raise`       raises plot window after each plot                            |
   |   `-noraise`      does not raise plot window after each plot                    |
   |   `-persist`      plots windows survive after main gnuplot program exits        |
   +---------------------------------------------------------------------------------+












   GNUPLOT 4.1                                                      241


   The options are shown above in their command-line syntax.  When
   entered as resources in ".Xdefaults", they require a different syn-
   tax.

   Example:
             gnuplot*gray: on

   ggnnuupplloott also provides a command line option (--ppooiinnttssiizzee <<vv>>) and a
   resource, ggnnuupplloott**ppooiinnttssiizzee:: <<vv>>, to control the size of points
   plotted with the ppooiinnttss plotting style.  The value vv is a real num-
   ber (greater than 0 and less than or equal to ten) used as a scaling
   factor for point sizes.  For example, --ppooiinnttssiizzee 22 uses points twice
   the default size, and --ppooiinnttssiizzee 00..55 uses points half the normal
   size.



             8877..66..22..  MMoonnoocchhrroommee__ooppttiioonnss


             For monochrome displays, ggnnuupplloott does not honor foreground
             or background colors.  The default is black-on-white.  --rrvv
             or ggnnuupplloott**rreevveerrsseeVViiddeeoo:: oonn requests white-on-black.




             8877..66..33..  CCoolloorr__rreessoouurrcceess


             For color displays, ggnnuupplloott honors the following resources
             (shown here with their default values) or the greyscale
             resources.  The values may be color names as listed in the
             BE rgb.txt file on your system, hexadecimal RGB color
             specifications (see BE documentation), or a color name
             followed by a comma and an iinntteennssiittyy value from 0 to 1.
             For example, bblluuee,, 00..55 means a half intensity blue.


























   GNUPLOT 4.1                                                      242


                    +--------------------------------+
                    |    gnuplot*background: white   |
                    |    gnuplot*textColor: black    |
                    |    gnuplot*borderColor: black  |
                    |    gnuplot*axisColor: black    |
                    |    gnuplot*line1Color: red     |
                    |    gnuplot*line2Color: green   |
                    |    gnuplot*line3Color: blue    |
                    |    gnuplot*line4Color: magenta |
                    |    gnuplot*line5Color: cyan    |
                    |    gnuplot*line6Color: sienna  |
                    |    gnuplot*line7Color: orange  |
                    |    gnuplot*line8Color: coral   |
                    +--------------------------------+



   The command-line syntax for these is, for example,

   Example:
             gnuplot -background coral




             8877..66..44..  GGrraayyssccaallee__rreessoouurrcceess


             When --ggrraayy is selected, ggnnuupplloott honors the following
             resources for grayscale or color displays (shown here with
             their default values).  Note that the default background
             is black.



                     +-------------------------------+
                     |    gnuplot*background: black  |
                     |    gnuplot*textGray: white    |
                     |    gnuplot*borderGray: gray50 |
                     |    gnuplot*axisGray: gray50   |
                     |    gnuplot*line1Gray: gray100 |
                     |    gnuplot*line2Gray: gray60  |
                     |    gnuplot*line3Gray: gray80  |
                     |    gnuplot*line4Gray: gray40  |
                     |    gnuplot*line5Gray: gray90  |
                     |    gnuplot*line6Gray: gray50  |
                     |    gnuplot*line7Gray: gray70  |
                     |    gnuplot*line8Gray: gray30  |
                     +-------------------------------+














   GNUPLOT 4.1                                                      243


             8877..66..55..  LLiinnee__rreessoouurrcceess


             ggnnuupplloott honors the following resources for setting the
             width (in pixels) of plot lines (shown here with their
             default values.)  0 or 1 means a minimal width line of 1
             pixel width.  A value of 2 or 3 may improve the appearance
             of some plots.



                       +---------------------------+
                       |    gnuplot*borderWidth: 2 |
                       |    gnuplot*axisWidth: 0   |
                       |    gnuplot*line1Width: 0  |
                       |    gnuplot*line2Width: 0  |
                       |    gnuplot*line3Width: 0  |
                       |    gnuplot*line4Width: 0  |
                       |    gnuplot*line5Width: 0  |
                       |    gnuplot*line6Width: 0  |
                       |    gnuplot*line7Width: 0  |
                       |    gnuplot*line8Width: 0  |
                       +---------------------------+



   ggnnuupplloott honors the following resources for setting the dash style
   used for plotting lines.  0 means a solid line.  A two-digit number
   jjkk (jj and kk are >= 1  and <= 9) means a dashed line with a repeated
   pattern of jj pixels on followed by kk pixels off.  For example, '16'
   is a "dotted" line with one pixel on followed by six pixels off.
   More elaborate on/off patterns can be specified with a four-digit
   value.  For example, '4441' is four on, four off, four on, one off.
   The default values shown below are for monochrome displays or mono-
   chrome rendering on color or grayscale displays.  For color dis-
   plays, the default for each is 0 (solid line) except for aaxxiissDDaasshheess
   which defaults to a '16' dotted line.



                     +------------------------------+
                     |    gnuplot*borderDashes: 0   |
                     |    gnuplot*axisDashes: 16    |
                     |    gnuplot*line1Dashes: 0    |
                     |    gnuplot*line2Dashes: 42   |
                     |    gnuplot*line3Dashes: 13   |
                     |    gnuplot*line4Dashes: 44   |
                     |    gnuplot*line5Dashes: 15   |
                     |    gnuplot*line6Dashes: 4441 |
                     |    gnuplot*line7Dashes: 42   |
                     |    gnuplot*line8Dashes: 13   |
                     +------------------------------+











   GNUPLOT 4.1                                                      244


        8877..77..  CCaannvvaass



        Syntax:
              set terminal canvas {size <xsize>, <ysize>} {fsize <font-
        size>}
                                  {{no}enhanced} {linewidth <lw>}
                                  {standalone {mousing} | name '<func-
        name>'}
                                  {jsdir 'URL/for/javascripts'}
                                  {title '<some string>'}

        where <xsize> and <ysize> set the size of the plot area in pix-
        els.  The default size in standalone mode is 600 by 400 pixels.
        The default font size is 10.  NB: Only one font is available,
        the ascii portion of Hershey simplex Roman provided in the file
        canvastext.js.  You can replace this with the file canvas-
        math.js, which contains also UTF-8 encoded Hershey simplex
        Greek and math symbols.

        The default ssttaannddaalloonnee mode creates an html page containing
        javascript code that renders the plot using the HTML 5 canvas
        element.  The html page links to two required javascript files
        'canvastext.js' and 'gnuplot_common.js'.  By default these
        point to local files, on unix-like systems usually in directory
        /usr/local/share/gnuplot/<version>/js.  See installation notes
        for other platforms. You can change this by using the jjssddiirr
        option to specify either a different local directory or a gen-
        eral URL.  The latter is usually appropriate if the plot is
        exported for viewing on remote client machines.

        All plots produced by the canvas terminal are mouseable.  The
        additional keyword mmoouussiinngg causes the ssttaannddaalloonnee mode to add a
        mouse-tracking box underneath the plot. It also adds a link to
        a javascript file 'gnuplot_mouse.js' and to a stylesheet for
        the mouse box 'gnuplot_mouse.css' in the same local or URL
        directory as 'canvastext.js'.

        The nnaammee option creates a file containing only javascript. Both
        the javascript function it contains and the id of the canvas
        element that it draws onto are taken from the following string
        parameter.  The commands
              set term canvas name 'fishplot'
              set output 'fishplot.js'
        will create a file containing a javascript function fishplot()
        that will draw onto a canvas with id=fishplot.  An html page
        that invokes this javascript function must also load the can-
        vastext.js function as described above.  A minimal html file to
        wrap the fishplot created above might be:

              <html>
              <head>










   GNUPLOT 4.1                                                      245


                  <script src="canvastext.js"></script>
                  <script src="gnuplot_common.js"></script>
              </head>
              <body onload="fishplot();">
                  <script src="fishplot.js"></script>
                  <canvas id="fishplot" width=600 height=400>
                      <div id="err_msg">No support for HTML 5 canvas
        element</div>
                  </canvas>
              </body>
              </html>




        8877..88..  CCggii


        The ccggii and hhccggii terminal drivers support SCO CGI drivers.
        hhccggii is for printers; the environment variable CGIPRNT must be
        set.  ccggii may be used for either a display or hardcopy; if the
        environment variable CGIDISP is set, then that display is used.
        Otherwise CGIPRNT is used.

        These terminals have no options.



        8877..99..  CCggmm


        The ccggmm terminal generates a Computer Graphics Metafile, Ver-
        sion 1.  This file format is a subset of the ANSI X3.122-1986
        standard entitled "Computer Graphics - Metafile for the Storage
        and Transfer of Picture Description Information".

        Syntax:
              set terminal cgm {color | monochrome} {solid | dashed}
        {{no}rotate}
                               {<mode>} {width <plot_width>} {linewidth
        <line_width>}
                               {font "<fontname>,<fontsize>"}
                               {<color0> <color1> <color2> ...}

        ssoolliidd draws all curves with solid lines, overriding any dashed
        patterns; <mode> is llaannddssccaappee, ppoorrttrraaiitt, or ddeeffaauulltt;
        <plot_width> is the assumed width of the plot in points;
        <line_width> is the line width in points (default 1); <font-
        name> is the name of a font (see list of fonts below) <font-
        size> is the size of the font in points (default 12).

        The first six options can be in any order.  Selecting ddeeffaauulltt
        sets all options to their default values.










   GNUPLOT 4.1                                                      246


        Each color must be of the form 'xrrggbb', where x is the lit-
        eral character 'x' and 'rrggbb' are the red, green and blue
        components in hex.  For example, 'x00ff00' is green.  The back-
        ground color is set first, then the plotting colors.

        Examples:
              set terminal cgm landscape color rotate dashed width 432
        \
                             linewidth 1  'Helvetica Bold' 12       #
        defaults
              set terminal cgm linewidth 2  14  # wider lines & larger
        font
              set terminal cgm portrait "Times Italic" 12
              set terminal cgm color solid      # no pesky dashes!




             8877..99..11..  CCggmm ffoonntt


             The first part of a Computer Graphics Metafile, the
             metafile description, includes a font table.  In the pic-
             ture body, a font is designated by an index into this ta-
             ble.  By default, this terminal generates a table with the
             following 35 fonts, plus six more with iittaalliicc replaced by
             oobblliiqquuee, or vice-versa (since at least the Microsoft
             Office and Corel Draw CGM import filters treat iittaalliicc and
             oobblliiqquuee as equivalent):


































   GNUPLOT 4.1                                                      247


                   +-----------------------------------+
                   |        CGM fonts                  |
                   +-----------------------------------+
                   |        Helvetica                  |
                   |        Helvetica Bold             |
                   |        Helvetica Oblique          |
                   |        Helvetica Bold Oblique     |
                   |        Times Roman                |
                   |        Times Bold                 |
                   |        Times Italic               |
                   |        Times Bold Italic          |
                   |        Courier                    |
                   |        Courier Bold               |
                   |        Courier Oblique            |
                   |        Courier Bold Oblique       |
                   |        Symbol                     |
                   |        Hershey/Cartographic_Roman |
                   |        Hershey/Cartographic_Greek |
                   |        Hershey/Simplex_Roman      |
                   |        Hershey/Simplex_Greek      |
                   |        Hershey/Simplex_Script     |
                   |        Hershey/Complex_Roman      |
                   |        Hershey/Complex_Greek      |
                   |        Hershey/Complex_Script     |
                   |        Hershey/Complex_Italic     |
                   |        Hershey/Complex_Cyrillic   |
                   |        Hershey/Duplex_Roman       |
                   |        Hershey/Triplex_Roman      |
                   |        Hershey/Triplex_Italic     |
                   |        Hershey/Gothic_German      |
                   |        Hershey/Gothic_English     |
                   |        Hershey/Gothic_Italian     |
                   |        Hershey/Symbol_Set_1       |
                   |        Hershey/Symbol_Set_2       |
                   |        Hershey/Symbol_Math        |
                   |        ZapfDingbats               |
                   |        Script                     |
                   |        15                         |
                   +-----------------------------------+


   The first thirteen of these fonts are required for WebCGM.  The
   Microsoft Office CGM import filter implements the 13 standard fonts
   listed above, and also 'ZapfDingbats' and 'Script'.  However, the
   script font may only be accessed under the name '15'.  For more on
   Microsoft import filter font substitutions, check its help file
   which you may find here:
     C:\Program Files\Microsoft Office\Office\Cgmimp32.hlp
   and/or its configuration file, which you may find here:
     C:\Program Files\Common Files\Microsoft
   Shared\Grphflt\Cgmimp32.cfg

   In the sseett tteerrmm command, you may specify a font name which does not










   GNUPLOT 4.1                                                      248


   appear in the default font table.  In that case, a new font table is
   constructed with the specified font as its first entry. You must
   ensure that the spelling, capitalization, and spacing of the name
   are appropriate for the application that will read the CGM file.
   (Gnuplot and any MIL-D-28003A compliant application ignore case in
   font names.)  If you need to add several new fonts, use several sseett
   tteerrmm commands.

   Example:
         set terminal cgm 'Old English'
         set terminal cgm 'Tengwar'
         set terminal cgm 'Arabic'
         set output 'myfile.cgm'
         plot ...
         set output

   You cannot introduce a new font in a sseett llaabbeell command.



             8877..99..22..  CCggmm ffoonnttssiizzee


             Fonts are scaled assuming the page is 6 inches wide.  If
             the ssiizzee command is used to change the aspect ratio of the
             page or the CGM file is converted to a different width,
             the resulting font sizes will be scaled up or down accord-
             ingly.  To change the assumed width, use the wwiiddtthh option.



             8877..99..33..  CCggmm lliinneewwiiddtthh


             The lliinneewwiiddtthh option sets the width of lines in pt.  The
             default width is 1 pt.  Scaling is affected by the actual
             width of the page, as discussed under the ffoonnttssiizzee and
             wwiiddtthh options.



             8877..99..44..  CCggmm rroottaattee


             The nnoorroottaattee option may be used to disable text rotation.
             For example, the CGM input filter for Word for Windows
             6.0c can accept rotated text, but the DRAW editor within
             Word cannot.  If you edit a graph (for example, to label a
             curve), all rotated text is restored to horizontal.  The Y
             axis label will then extend beyond the clip boundary.
             With nnoorroottaattee, the Y axis label starts in a less attrac-
             tive location, but the page can be edited without damage.
             The rroottaattee option confirms the default behavior.










   GNUPLOT 4.1                                                      249


             8877..99..55..  CCggmm ssoolliidd


             The ssoolliidd option may be used to disable dashed line styles
             in the plots.  This is useful when color is enabled and
             the dashing of the lines detracts from the appearance of
             the plot. The ddaasshheedd option confirms the default behavior,
             which gives a different dash pattern to each line type.



             8877..99..66..  CCggmm ssiizzee


             Default size of a CGM plot is 32599 units wide and 23457
             units high for landscape, or 23457 units wide by 32599
             units high for portrait.



             8877..99..77..  CCggmm wwiiddtthh


             All distances in the CGM file are in abstract units.  The
             application that reads the file determines the size of the
             final plot.  By default, the width of the final plot is
             assumed to be 6 inches (15.24 cm).  This distance is used
             to calculate the correct font size, and may be changed
             with the wwiiddtthh option.  The keyword should be followed by
             the width in points.  (Here, a point is 1/72 inch, as in
             PostScript.  This unit is known as a "big point" in TeX.)
             Gnuplot eexxpprreessssiioonnss can be used to convert from other
             units.

             Example:
                   set terminal cgm width 432            # default
                   set terminal cgm width 6*72           # same as
             above
                   set terminal cgm width 10/2.54*72     # 10 cm wide



             8877..99..88..  CCggmm nnooffoonnttlliisstt


             The default font table includes the fonts recommended for
             WebCGM, which are compatible with the Computer Graphics
             Metafile input filter for Microsoft Office and Corel Draw.
             Another application might use different fonts and/or dif-
             ferent font names, which may not be documented.  The
             nnooffoonnttlliisstt (synonym wwiinnwwoorrdd66) option deletes the font ta-
             ble from the CGM file.  In this case, the reading applica-
             tion should use a default table.  Gnuplot will still use










   GNUPLOT 4.1                                                      250


             its own default font table to select font indices.  Thus,
             'Helvetica' will give you an index of 1, which should get
             you the first entry in your application's default font ta-
             ble. 'Helvetica Bold' will give you its second entry, etc.




        8877..1100..  CCoorreell


        The ccoorreell terminal driver supports CorelDraw.

        Syntax:
              set terminal corel {  default
                                  | {monochrome | color
                                       {"<font>" {<fontsize>
                                          {<xsize> <ysize> {<linewidth>
        }}}}}

        where the fontsize and linewidth are specified in points and
        the sizes in inches.  The defaults are monochrome, "Switzer-
        landLight", 22, 8.2, 10 and 1.2.



        8877..1111..  DDeebbuugg


        This terminal is provided to allow for the debugging of ggnnuu--
        pplloott.  It is likely to be of use only for users who are modify-
        ing the source code.



        8877..1122..  DDoossppcc


        The ddoossppcc terminal driver supports PCs with arbitrary graphics
        boards, which will be automatically detected.  It should be
        used only if you are not using the gcc or Zortec C/C++ compil-
        ers.



        8877..1133..  DDuummbb


        The dduummbb terminal driver has an optional size specification and
        trailing linefeed control.

        Syntax:
              set terminal dumb {[no]feed} {<xsize> <ysize>}










   GNUPLOT 4.1                                                      251


                                {[no]enhanced}

        where <xsize> and <ysize> set the size of the dumb terminals.
        Default is 79 by 24. The last newline is printed only if ffeeeedd
        is enabled.

        Examples:
              set term dumb nofeed
              set term dumb 79 49 # VGA screen---why would anyone do
        that?



        8877..1144..  DDxxff


        The ddxxff terminal driver creates pictures that can be imported
        into AutoCad (Release 10.x).  It has no options of its own, but
        some features of its plots may be modified by other means.  The
        default size is 120x80 AutoCad units, which can be changed by
        sseett ssiizzee.  ddxxff uses seven colors (white, red, yellow, green,
        cyan, blue and magenta), which can be changed only by modifying
        the source file.  If a black-and-white plotting device is used,
        the colors are mapped to differing line thicknesses.  See the
        description of the AutoCad print/plot command.



        8877..1155..  DDxxyy880000aa


        This terminal driver supports the Roland DXY800A plotter.  It
        has no options.



        8877..1166..  EEeeppiicc


        The eeeeppiicc terminal driver supports the extended LaTeX picture
        environment.  It is an alternative to the llaatteexx driver.

        The output of this terminal is intended for use with the
        "eepic.sty" macro package for LaTeX.  To use it, you need
        "eepic.sty", "epic.sty" and a printer driver that supports the
        "tpic" \specials.  If your printer driver doesn't support those
        \specials, "eepicemu.sty" will enable you to use some of them.
        dvips and dvipdfm do support the "tpic" \specials.

        Syntax:
           set terminal eepic {default} {color|dashed} {rotate} {size
        XX,YY}
                              {small|tiny|<fontsize>}










   GNUPLOT 4.1                                                      252


        Options: You can give options in any order you wish.  'color'
        causes gnuplot to produce \color{...} commands so that the
        graphs are colored. Using this option, you must include \usepa-
        ckage{color} in the preambel of your latex document.  'dashed'
        will allow dashed line types; without this option, only solid
        lines with varying thickness will be used.  'dashed' and
        'color' are mutually exclusive; if 'color' is specified, then
        'dashed' will be ignored.  'rotate' will enable true rotated
        text (by 90 degrees). Otherwise, rotated text will be typeset
        with letters stacked above each other. If you use this option
        you must include \usepackage{graphicx} in the preamble.
        'small' will use \scriptsize symbols as point markers (Probably
        does not work with TeX, only LaTeX2e). Default is to use the
        default math size.  'tiny' uses \scriptscriptstyle symbols.
        'default' resets all options to their defaults = no color, no
        dashed lines, pseudo-rotated (stacked) text, large point sym-
        bols.  <fontsize> is a number which specifies the font size
        inside the picture environment; the unit is pt (points), i.e.,
        10 pt equals approx. 3.5 mm.  If fontsize is not specified,
        then all text inside the picture will be set in \footnotesize.

        Notes: Remember to escape the # character (or other chars mean-
        ingful to (La-)TeX) by \\ (2 backslashes).  It seems that
        dashed lines become solid lines when the vertices of a plot are
        too close. (I do not know if that is a general problem with the
        tpic specials, or if it is caused by a bug in eepic.sty or
        dvips/dvipdfm.)  The default size of an eepic plot is 5x3
        inches. You can change this using the ssiizzee terminal option.
        Points, among other things, are drawn using the LaTeX commands
        "\Diamond", "\Box", etc.  These commands no longer belong to
        the LaTeX2e core; they are included in the latexsym package,
        which is part of the base distribution and thus part of any
        LaTeX implementation. Please do not forget to use this package.
        Instead of latexsym, you can also include the amssymb package.
        All drivers for LaTeX offer a special way of controlling text
        positioning: If any text string begins with '{', you also need
        to include a '}' at the end of the text, and the whole text
        will be centered both horizontally and vertically.  If the text
        string begins with '[', you need to follow this with a position
        specification (up to two out of t,b,l,r), ']{', the text
        itself, and finally '}'.  The text itself may be anything LaTeX
        can typeset as an LR-box.  '\rule{}{}'s may help for best posi-
        tioning.

        Examples: set term eepic
          output graphs as eepic macros inside a picture environment;
          \input the resulting file in your LaTeX document.
        set term eepic color tiny rotate 8
          eepic macros with \color macros, \scripscriptsize point mark-
        ers,
          true rotated text, and all text set with 8pt.

        About label positioning: Use gnuplot defaults (mostly sensible,










   GNUPLOT 4.1                                                      253


        but sometimes not really best):
               set title '\LaTeX\ -- $ \gamma $'
        Force centering both horizontally and vertically:
               set label '{\LaTeX\ -- $ \gamma $}' at 0,0
        Specify own positioning (top here):
               set xlabel '[t]{\LaTeX\ -- $ \gamma $}'
        The other label -- account for long ticlabels:
               set ylabel '[r]{\LaTeX\ -- $ \gamma $\rule{7mm}{0pt}}'



        8877..1177..  EEmmff


        The eemmff terminal generates an Enhanced Metafile Format file.
        This file format is recognized by many Windows applications.

        Syntax:
              set terminal emf {color | monochrome} {solid | dashed}
                               {enhanced {noproportional}}
                               {rounded | butt}
                               {linewidth <LW>} {dashlength <DL>} {size
        XX,YY}
                               {"<fontname>"} {<fontsize>}    #old syn-
        tax
                               {font "<fontname>,<fontsize>"} #new syn-
        tax

        In mmoonnoocchhrroommee mode successive line types cycle through dash
        patterns.  In ccoolloorr mode successive line types use successive
        colors, and only after all 8 default colors are exhausted is
        the dash pattern incremented.  ssoolliidd draws all curves with
        solid lines, overriding any dashed patterns; lliinneewwiiddtthh <<ffaaccttoorr>>
        multiplies all line widths by this factor.  ddaasshhlleennggtthh <<ffaaccttoorr>>
        is useful for thick lines.  <fontname> is the name of a font;
        and <<ffoonnttssiizzee>> is the size of the font in points.

        The nominal size of the output image defaults to 1024x768 in
        arbitrary units. You may specify a different nominal size using
        the ssiizzee option.

        Enhanced text mode tries to approximate proportional character
        spacing.  If you are using a monospaced font, or don't like the
        approximation, you can turn off this correction using the
        nnoopprrooppoorrttiioonnaall option.

        The default settings are ccoolloorr ddaasshheedd ffoonntt ""AArriiaall,,1122"" ssiizzee
        11002244,,776688 Selecting ddeeffaauulltt sets all options to their default
        values.

        Examples:
              set terminal emf 'Times Roman Italic' 12
              set terminal emf color solid    # no pesky dashes!










   GNUPLOT 4.1                                                      254


        8877..1188..  EEmmxxvvggaa


        The eemmxxvvggaa, eemmxxvveessaa and vvggaall terminal drivers support PCs with
        SVGA, vesa SVGA and VGA graphics boards, respectively.  They
        are intended to be compiled with "emx-gcc" under either DOS or
        OS/2.  They also need VESA and SVGAKIT maintained by Johannes
        Martin (JMARTIN@GOOFY.ZDV.UNI-MAINZ.DE) with additions by David
        J. Liu (liu@phri.nyu.edu).

        Syntax:
              set terminal emxvga
              set terminal emxvesa {vesa-mode}
              set terminal vgal

        The only option is the vesa mode for eemmxxvveessaa, which defaults to
        G640x480x256.



        8877..1199..  EEppssllaatteexx


        The eeppssllaatteexx driver generates output for further processing by
        LaTeX.

        Syntax:
              set terminal epslatex   {default}
              set terminal epslatex   {standalone | input}
                                      {oldstyle | newstyle}
                                      {level1 | leveldefault}
                                      {color | colour | monochrome}
                                      {solid | dashed}
                                      {dashlength | dl <DL>}
                                      {linewidth | lw <LW>}
                                      {rounded | butt}
                                      {clip | noclip}
                                      {palfuncparam <samples>{,<maxde-
        viation>}}
                                      {size <XX>{unit},<YY>{unit}}
                                      {header <header> | noheader}
                                      {blacktext | colortext | colour-
        text}
                                      {{font} "fontname{,fontsize}"
        {<fontsize>}}

        The epslatex terminal prints a plot as tteerrmmiinnaall ppoossttssccrriipptt eeppss
        but transfers the texts to LaTeX instead of including in the
        PostScript code. Thus, many options are the same as in the
        ppoossttssccrriipptt tteerrmmiinnaall.

        The appearance of the epslatex terminal changed between ver-
        sions 4.0 and 4.2 to reach better consistency with the










   GNUPLOT 4.1                                                      255


        postscript terminal: The plot size has been changed from 5 x 3
        inches to 5 x 3.5 inches; the character width is now estimated
        to be 60% of the font size while the old epslatex terminal used
        50%;  now, the larger number of postscript linetypes and sym-
        bols are used.  To reach an appearance that is nearly identical
        to the old one specify the option oollddssttyyllee. (In fact some small
        differences remain: the symbol sizes are slightly different,
        the tics are half as large as in the old terminal which can be
        changed using sseett ttiiccss ssccaallee, and the arrows have all features
        as in the postscript terminal.)

        If you see the error message
              "Can't find PostScript prologue file ... "
        Please see and follow the instructions in ppoossttssccrriipptt pprroolloogguuee.

        The option ccoolloorr enables color, while mmoonnoocchhrroommee prefers black
        and white drawing elements. Further, mmoonnoocchhrroommee uses gray
        ppaalleettttee but it does not change color of objects specified with
        an explicit ccoolloorrssppeecc.  ssoolliidd draws all plots with solid lines,
        overriding any dashed patterns.  ddaasshhlleennggtthh or ddll scales the
        length of the dashed-line segments by <DL>, which is a float-
        ing-point number greater than zero.  lliinneewwiiddtthh or llww scales all
        linewidths by <LW>.

        By default the generated PostScript code uses language features
        that were introduced in PostScript Level 2, notably filters and
        pattern-fill of irregular objects such as filledcurves.  Post-
        Script Level 2 features are conditionally protected so that
        PostScript Level 1 interpreters do not issue errors but,
        rather, display a message or a PostScript Level 1 approxima-
        tion.  The lleevveell11 option substitutes PostScript Level 1 approx-
        imations of these features and uses no PostScript Level 2 code.
        This may be required by some old printers and old versions of
        Adobe Illustrator.  The flag lleevveell11 can be toggled later by
        editing a single line in the PostScript output file to force
        PostScript Level 1 interpretation.  In the case of files con-
        taining level 2 code, the above features will not appear or
        will be replaced by a note when this flag is set or when the
        interpreting program does not indicate that it understands
        level 2 PostScript or higher.

        rroouunnddeedd sets line caps and line joins to be rounded; bbuutttt is
        the default, butt caps and mitered joins.

        cclliipp tells PostScript to clip all output to the bounding box;
        nnoocclliipp is the default.

        ppaallffuunnccppaarraamm controls how sseett ppaalleettttee ffuunnccttiioonnss are encoded as
        gradients in the output. Analytic color component functions
        (set via sseett ppaalleettttee ffuunnccttiioonnss) are encoded as linear interpo-
        lated gradients in the postscript output:  The color component
        functions are sampled at <samples> points and all points are
        removed from this gradient which can be removed without










   GNUPLOT 4.1                                                      256


        changing the resulting colors by more than <maxdeviation>. For
        almost every useful palette you may savely leave the defaults
        of <samples>=2000 and <maxdeviation>=0.003 untouched.

        The default size for postscript output is 10 inches x 7 inches.
        The default for eps output is 5 x 3.5 inches.  The ssiizzee option
        changes this to whatever the user requests. By default the X
        and Y sizes are taken to be in inches, but other units are pos-
        sibly (currently only cm). The BoundingBox of the plot is cor-
        rectly adjusted to contain the resized image.  Screen coordi-
        nates always run from 0.0 to 1.0 along the full length of the
        plot edges as specified by the ssiizzee option.  NB: tthhiiss iiss aa
        cchhaannggee ffrroomm tthhee pprreevviioouussllyy rreeccoommmmeennddeedd mmeetthhoodd ooff uussiinngg tthhee sseett
        ssiizzee ccoommmmaanndd pprriioorr ttoo sseettttiinngg tthhee tteerrmmiinnaall ttyyppee.  The old
        method left the BoundingBox unchanged and screen coordinates
        did not correspond to the actual limits of the plot.

        bbllaacckktteexxtt forces all text to be written in black even in color
        mode;

        The epslatex driver offers a special way of controlling text
        positioning: (a) If any text string begins with '{', you also
        need to include a '}' at the end of the text, and the whole
        text will be centered both horizontally and vertically by
        LaTeX.  (b) If the text string begins with '[', you need to
        continue it with: a position specification (up to two out of
        t,b,l,r,c), ']{', the text itself, and finally, '}'. The text
        itself may be anything LaTeX can typeset as an LR-box.
        \rule{}{}'s may help for best positioning.  See also the docu-
        mentation for the ppssllaatteexx terminal driver.  To create multiline
        labels, use \shortstack, for example
           set ylabel '[r]{\shortstack{first line \\ second line}}'

        The bbaacckk option of sseett llaabbeell commands is handled slightly dif-
        ferent than in other terminals. Labels using 'back' are printed
        behind all other elements of the plot while labels using
        'front' are printed above everything else.

        The driver produces two different files, one for the eps part
        of the figure and one for the LaTeX part. The name of the LaTeX
        file is taken from the sseett oouuttppuutt command. The name of the eps
        file is derived by replacing the file extension (normally ..tteexx)
        with ..eeppss instead.  There is no LaTeX output if no output file
        is given!  Remember to close the oouuttppuutt ffiillee before next plot
        unless in mmuullttiipplloott mode.

        In your LaTeX documents use '\input{filename}' to include the
        figure.  The ..eeppss file is included by the command \include-
        graphics{...}, so you must also include \usepackage{graphicx}
        in the LaTeX preamble.  If you want to use coloured text
        (option tteexxttccoolloouurr) you also have to include \usepackage{color}
        in the LaTeX preamble.











   GNUPLOT 4.1                                                      257


        Pdf files can be made from the eps file using 'epstopdf'. If
        the graphics package is properly configured, the LaTeX files
        can also be processed by pdflatex without changes, using the
        pdf files instead of the eps files.  The behaviour concerning
        font selection depends on the header mode.  In all cases, the
        given font size is used for the calculation of proper spacing.
        When not using the ssttaannddaalloonnee mode the actual LaTeX font and
        font size at the point of inclusion is taken, so use LaTeX com-
        mands for changing fonts. If you use e.g. 12pt as font size for
        your LaTeX document, use '"" 12' as options. The font name is
        ignored. If using ssttaannddaalloonnee the given font and font size are
        used, see below for a detailed description.

        If text is printed coloured is controlled by the TeX booleans
        \ifGPcolor and \ifGPblacktext. Only if \ifGPcolor is true and
        \ifGPblacktext is false, text is printed coloured. You may
        either change them in the generated TeX file or provide them
        globally in your TeX file, for example by using
           \newif\ifGPblacktext
           \GPblacktexttrue
        in the preamble of your document. The local assignment is only
        done if no global value is given.

        When using the epslatex terminal give the name of the TeX file
        in the sseett oouuttppuutt command including the file extension (nor-
        mally ".tex").  The eps filename is generated by replacing the
        extension by ".eps".

        If using the ssttaannddaalloonnee mode a complete LaTeX header is added
        to the LaTeX file; and "-inc" is added to the filename of the
        eps file.  The ssttaannddaalloonnee mode generates a TeX file that pro-
        duces output with the correct size when using dvips, pdfTeX, or
        VTeX.  The default, iinnppuutt, generates a file that has to be
        included into a LaTeX document using the \input command.

        If a font other than "" or "default" is given it is interpreted
        as LaTeX font name.  It contains up to three parts, separated
        by a comma: 'fontname,fontseries,fontshape'.  If the default
        fontshape or fontseries are requested, they can be omitted.
        Thus, the real syntax for the fontname is '[font-
        name][,fontseries][,fontshape]'.  The naming convention for all
        parts is given by the LaTeX font scheme.  The fontname is 3 to
        4 characters long and is built as follows: One character for
        the font vendor, two characters for the name of the font, and
        optionally one additional character for special fonts, e.g.,
        'j' for fonts with old-style numerals or 'x' for expert fonts.
        The names of many fonts is described in
                  http://www.tug.org/fontname/fontname.pdf
        For example, 'cmr' stands for Computer Modern Roman, 'ptm' for
        Times-Roman, and 'phv' for Helvetica.  The font series denotes
        the thickness of the glyphs, in most cases 'm' for normal
        ("medium") and 'bx' or 'b' for bold fonts.  The font shape is
        'n' for upright, 'it' for italics, 'sl' for slanted, or 'sc'










   GNUPLOT 4.1                                                      258


        for small caps, in general.  Some fonts may provide different
        font series or shapes.

        Examples:

        Use Times-Roman boldface (with the same shape as in the sur-
        rounding text):
              set terminal epslatex 'ptm,bx'
        Use Helvetica, boldface, italics:
              set terminal epslatex 'phv,bx,it'
        Continue to use the surrounding font in slanted shape:
              set terminal epslatex ',,sl'
        Use small capitals:
              set terminal epslatex ',,sc'

        By this method, only text fonts are changed. If you also want
        to change the math fonts you have to use the "gnuplot.cfg" file
        or the hheeaaddeerr option, described below.

        In standalone mode, the font size is taken from the given font
        size in the sseett tteerrmmiinnaall command. To be able to use a specified
        font size, a file "size<size>.clo" has to reside in the LaTeX
        search path.  By default, 10pt, 11pt, and 12pt are supported.
        If the package "extsizes" is installed, 8pt, 9pt, 14pt, 17pt,
        and 20pt are added.

        The hheeaaddeerr option takes a string as argument.  This string is
        written into the generated LaTeX file.  If using the ssttaannddaalloonnee
        mode, it is written into the preamble, directly before the
        \begin{document} command.  In the iinnppuutt mode, it is placed
        directly after the \begingroup command to ensure that all set-
        tings are local to the plot.

        Examples:

        Use T1 fontencoding, change the text and math font to Times-
        Roman as well as the sans-serif font to Helvetica:
            set terminal epslatex standalone header \
            "\\usepackage[T1]{fontenc}\n\\usepackage{mathptmx}\n\\usep-
        ackage{helvet}"
        Use a boldface font in the plot, not influencing the text out-
        side the plot:
            set terminal epslatex input header "\\bfseries"

        If the file "gnuplot.cfg" is found by LaTeX it is input in the
        preamble the LaTeX document, when using ssttaannddaalloonnee mode.  It
        can be used for further settings, e.g., changing the document
        font to Times-Roman, Helvetica, and Courier, including math
        fonts (handled by "mathptmx.sty"):
              \usepackage{mathptmx}
              \usepackage[scaled=0.92]{helvet}
              \usepackage{courier}
        The file "gnuplot.cfg" is loaded before the header information










   GNUPLOT 4.1                                                      259


        given by the hheeaaddeerr command.  Thus, you can use hheeaaddeerr to over-
        write some of settings performed using "gnuplot.cfg"




        8877..2200..  EEppssoonn__118800ddppii


        This driver supports a family of Epson printers and deriva-
        tives.

        eeppssoonn__118800ddppii and eeppssoonn__6600ddppii are drivers for Epson LQ-style
        24-pin printers with resolutions of 180 and 60 dots per inch,
        respectively.

        eeppssoonn__llxx880000 is a generic 9-pin driver appropriate for printers
        like the Epson LX-800, the Star NL-10 and NX-1000, the PRO-
        PRINTER, and so forth.

        nneecc__ccpp66 is generic 24-pin driver that can be used for printers
        like the NEC CP6 and the Epson LQ-800.

        The ookkiiddaattaa driver supports the 9-pin OKIDATA 320/321 Standard
        printers.

        The ssttaarrcc driver is for the Star Color Printer.

        The ttaannddyy__6600ddppii driver is for the Tandy DMP-130 series of
        9-pin, 60-dpi printers.

        The ddppuu441144 driver is for the Seiko DPU-414 thermal printer.

        nneecc__ccpp66 has the options:

        Syntax:
              set terminal nec_cp6 {monochrome | colour | draft}

        which defaults to monochrome.

        ddppuu441144 has the options:

        Syntax:
              set terminal dpu414 {small | medium | large} {normal |
        draft}

        which defaults to medium (=font size) and normal.  Preferred
        combinations are mmeeddiiuumm nnoorrmmaall and ssmmaallll ddrraafftt.















   GNUPLOT 4.1                                                      260


        8877..2211..  EExxccll


        The eexxccll terminal driver supports Talaris printers such as the
        EXCL Laser printer and the 1590.  It has no options.



        8877..2222..  FFiigg


        The ffiigg terminal device generates output in the Fig graphics
        language.

        Syntax:
              set terminal fig {monochrome | color}
                               {landscape | portrait}
                               {small | big | size <xsize> <ysize>}
                               {metric | inches}
                               {pointsmax <max_points>}
                               {solid | dashed}
                               {font <fontname>} {fontsize <fsize>}
                               {textnormal | {textspecial texthidden
        textrigid}}
                               {{thickness|linewidth} <units>}
                               {depth <layer>}
                               {version <number>}

        mmoonnoocchhrroommee and ccoolloorr determine whether the picture is black-
        and-white or ccoolloorr.  ssmmaallll and bbiigg produce a 5x3 or 8x5 inch
        graph in the default llaannddssccaappee mode and 3x5 or 5x8 inches in
        ppoorrttrraaiitt mode.  ssiizzee sets (overrides) the size of the drawing
        area to <xsize>*<ysize> in units of inches or centimeters
        depending on the iinncchheess or mmeettrriicc setting in effect.  The lat-
        ter settings is also used as default units for editing with
        "xfig".

        ppooiinnttssmmaaxx <<mmaaxx__ppooiinnttss>> sets the maximum number of points per
        polyline.

        ssoolliidd inhibits automatic usage of ddaasshhed lines when solid
        linestyles are used up, which otherwise occurs.

        ffoonnttssiizzee sets the size of the text font to <fsize> points.
        tteexxttnnoorrmmaall resets the text flags and selects postscript fonts,
        tteexxttssppeecciiaall sets the text flags for LaTeX specials, tteexxtthhiiddddeenn
        sets the hidden flag and tteexxttrriiggiidd the rigid flag.

        ddeepptthh sets the default depth layer for all lines and text.  The
        default depth is 10 to leave room for adding material with
        "xfig" on top of the plot.

        vveerrssiioonn sets the format version of the generated fig output.










   GNUPLOT 4.1                                                      261


        Currently only versions 3.1 and 3.2 are supported.

        tthhiicckknneessss sets the default line thickness, which is 1 if not
        specified.  Overriding the thickness can be achieved by adding
        a multiple of 100 to the lliinneettyyppee value for a pplloott command.  In
        a similar way the ddeepptthh of plot elements (with respect to the
        default depth) can be controlled by adding a multiple of 1000
        to <linetype>.  The depth is then <layer> + <linetype>/1000 and
        the thickness is (<linetype>%1000)/100 or, if that is zero, the
        default line thickness. lliinneewwiiddtthh is a synonym for tthhiicckknneessss.

        Additional point-plot symbols are also available with the ffiigg
        driver. The symbols can be used through ppooiinnttttyyppee values % 100
        above 50, with different fill intensities controlled by <point-
        type> % 5 and outlines in black (for <pointtype> % 10 < 5) or
        in the current color.  Available symbols are
                50 - 59:  circles
                60 - 69:  squares
                70 - 79:  diamonds
                80 - 89:  upwards triangles
                90 - 99:  downwards triangles
        The size of these symbols is linked to the font size.  The
        depth of symbols is by default one less than the depth for
        lines to achieve nice error bars.  If <pointtype> is above
        1000, the depth is <layer> + <pointtype>/1000-1.  If <point-
        type>%1000 is above 100, the fill color is (<point-
        type>%1000)/100-1.

        Available fill colors are (from 1 to 9): black, blue, green,
        cyan, red, magenta, yellow, white and dark blue (in monochrome
        mode: black for 1 to 6 and white for 7 to 9).

        See pplloott wwiitthh for details of <linetype> and <pointtype>.

        The bbiigg option is a substitute for the bbffiigg terminal in earlier
        versions, which is no longer supported.

        Examples:
              set terminal fig monochrome small pointsmax 1000  #
        defaults

              plot 'file.dat' with points linetype 102 pointtype 759
        would produce circles with a blue outline of width 1 and yellow
        fill color.

              plot 'file.dat' using 1:2:3 with err linetype 1 pointtype
        554
        would produce errorbars with black lines and circles filled
        red.  These circles are one layer above the lines (at depth 9
        by default).

        To plot the error bars on top of the circles use
              plot 'file.dat' using 1:2:3 with err linetype 1 pointtype










   GNUPLOT 4.1                                                      262


        2554



        8877..2233..  GGggii


        The ggggii driver can run on different targets as X or svgalib.

        Syntax:
           set terminal ggi [acceleration <integer>] [[mode] {mode}]

        In X the window cannot be resized using window manager handles,
        but the mode can be given with the mode option, e.g.:
         - V1024x768
         - V800x600
         - V640x480
         - V320x200
        Please refer to the ggi documentation for other modes. The
        'mode' keyword is optional. It is recommended to select the
        target by environment variables as explained in the libggi man-
        ual page. To get DGA on X, you should for example
           bash> export GGI_DISPLAY=DGA
           csh>  setenv GGI_DISPLAY DGA

        'acceleration' is only used for targets which report relative
        pointer motion events (e.g. DGA) and is a strictly positive
        integer multiplication factor for the relative distances.  The
        default for acceleration is 7.

        Examples:
           set term ggi acc 10
           set term ggi acc 1 mode V1024x768
           set term ggi V1024x768



        8877..2244..  GGiiff


        Syntax:
              set terminal gif
                     {{no}transparent} {rounded|butt}
                     {linewidth <lw>} {dashlength <dl>}
                     {tiny | small | medium | large | giant}
                     {font "<face> {,<pointsize>}"} {{no}enhanced}
                     {size <x>,<y>} {{no}crop}
                     {animate {delay <d>} {loop <n>} {{no}optimize}}
                     {<background_color>}

        PNG, JPEG and GIF images are created using the external library
        libgd.  GIF plots may be viewed interactively by piping the
        output to the 'display' program from the ImageMagick package as










   GNUPLOT 4.1                                                      263


        follows:
                       set term gif
                       set output '| display gif:-'
        You can view the output from successive plot commands interac-
        tively by typing <space> in the display window.  To save the
        current plot to a file, left click in the display window and
        choose ssaavvee.

        ttrraannssppaarreenntt instructs the driver to make the background color
        transparent.  Default is nnoottrraannssppaarreenntt.

        The lliinneewwiiddtthh and ddaasshhlleennggtthh options are scaling factors that
        affect all lines drawn, i.e. they are multiplied by values
        requested in various drawing commands.

        bbuutttt instructs the driver to use a line drawing method that
        does not overshoot the desired end point of a line.  This set-
        ting is only applicable for line widths greater than 1.  This
        setting is most useful when drawing horizontal or vertical
        lines.  Default is rroouunnddeedd.

        The details of font selection are complicated.  Two equivalent
        simple examples are given below:
             set term gif font arial 11
             set term gif font "arial,11"
        For more information please see the separate section under
        ffoonnttss.

        The aanniimmaattee option is available only if your local gd library
        supports the creation of animated gifs. The default delay
        between display of successive images may be specified in units
        of 1/100 second (default 5).  The actual delay may vary depend-
        ing on the program used as a viewer.  Number of animation loops
        can be specified, default 0 means infinity.  An animation
        sequence is terminated by the next sseett oouuttppuutt or sseett tteerrmm com-
        mand.  The ooppttiimmiizzee option has two effects on the animation.

        1) A single color map is used for the entire animation. This
        requires that all colors used in any frame of the animation are
        already defined in the first frame.

        2) If possible, only the portions of a frame that differ from
        the previous frame are stored in the animation file.  This
        space saving may not be possible if the animation uses trans-
        parency.

        Both of these optimizations are intended to produce a smaller
        output file, but the decrease in size is probably only signifi-
        cant for long animations or very small frame sizes.  The nnoooopp--
        ttiimmiizzee option turns off both of the effects just described.
        Each frame is stored in its entirety along with a private color
        map.  Note that it is possible to post-process a non-optimized
        animation using external utilities, and this post-processing










   GNUPLOT 4.1                                                      264


        can yield a smaller file than gnuplot's internal optimization
        mode.  The default is nnooooppttiimmiizzee.

        The output plot size <x,y> is given in pixels---it defaults to
        640x480.  Please see additional information under ccaannvvaass and
        sseett ssiizzee.  Blank space at the edges of the finished plot may be
        trimmed using the ccrroopp option, resulting in a smaller final
        image size. Default is nnooccrroopp.

        The background color must be given in the form 'xrrggbb', where
        x is the literal character 'x' and 'rrggbb' are the red, green
        and blue components in hexadecimal.  For example, 'x00ff00' is
        green.  The specification of additional colors other than the
        background is deprecated.





             8877..2244..11..  EExxaammpplleess


                   set terminal gif medium size 640,480 xffffff

             Use the medium size built-in non-scaleable, non-rotatable
             font.  Use white (xffffff) for the non-transparent back-
             ground.

                   set terminal gif font arial 14 enhanced

             Searches for a scalable font with face name 'arial' and
             sets the font size to 14pt.  Please see ffoonnttss for details
             of how the font search is done.  Because this is a scal-
             able font, we can use enhanced text mode.

                   set term gif animate transparent opt delay 10 size
             200,200 x000000
                   load "animate2.dem"

             Open the gif terminal for creation of an animated gif
             file.  The individual frames of the animation sequence are
             created by the script file animate2.dem from the standard
             collection of demos.




        8877..2255..  GGnnuuggrraapphh((GGNNUU pplloottuuttiillss))


        The ggnnuuggrraapphh driver produces device-independent output in the
        GNU plot graphics language.  The default size of the PostScript
        results generated by "plot2ps" is 5 x 3 inches; this can be










   GNUPLOT 4.1                                                      265


        increased up to about 8.25 x 8.25 by sseett ssiizzee.

        Syntax:
              set terminal gnugraph {"<fontname>"} {<fontsize>}
                                    {type <pt>} {size "<size>"}

        which defaults to 10-point "Courier".

        For ttyyppee, the following options are accepted: XX, ppnnmm, ggiiff, aaii,
        ppss, ccggmm, ffiigg, ppccll55, hhppggll, tteekk, and mmeettaa (default). The ssiizzee
        option (default is a4) is passed straight through to plotutils,
        it's the user's responsibility to provide correct values.
        Details can be found in the plotutils documentation.

        Examples:
              set terminal gnugraph type hpgl size "a4"
              set terminal gnugraph size "a4,xoffset=-5mm,yoff-
        set=2.0cm" type pnm

        There is a non-GNU version of the ggnnuuggrraapphh driver which cannot
        be compiled unless this version is left out.



        8877..2266..  GGppiicc


        The ggppiicc terminal driver generates GPIC graphs in the Free
        Software Foundations's "groff" package.  The default size is 5
        x 3 inches.  The only option is the origin, which defaults to
        (0,0).

        Syntax:
              set terminal gpic {<x> <y>}

        where xx and yy are in inches.

        A simple graph can be formatted using

              groff -p -mpic -Tps file.pic > file.ps.

        The output from pic can be pipe-lined into eqn, so it is possi-
        ble to put complex functions in a graph with the sseett llaabbeell and
        sseett {{xx//yy}}llaabbeell commands.  For instance,

              set ylab '@space 0 int from 0 to x alpha ( t ) roman d
        t@'

        will label the y axis with a nice integral if formatted with
        the command:

              gpic filename.pic | geqn -d@@ -Tps | groff -m[macro-pack-
        age] -Tps










   GNUPLOT 4.1                                                      266


                  > filename.ps

        Figures made this way can be scaled to fit into a document.
        The pic language is easy to understand, so the graphs can be
        edited by hand if need be.  All co-ordinates in the pic-file
        produced by ggnnuupplloott are given as x+gnuplotx and y+gnuploty.  By
        default x and y are given the value 0.  If this line is removed
        with an editor in a number of files, one can put several graphs
        in one figure like this (default size is 5.0x3.0 inches):

              .PS 8.0
              x=0;y=3
              copy "figa.pic"
              x=5;y=3
              copy "figb.pic"
              x=0;y=0
              copy "figc.pic"
              x=5;y=0
              copy "figd.pic"
              .PE

        This will produce an 8-inch-wide figure with four graphs in two
        rows on top of each other.

        One can also achieve the same thing by the command

              set terminal gpic x y

        for example, using

              .PS 6.0
              copy "trig.pic"
              .PE



        8877..2277..  GGpprr


        The ggpprr terminal driver supports the Apollo Graphics Primitive
        Resource for a fixed-size window.  It has no options.

        If a variable window size is desired, use the aappoolllloo terminal
        instead.



        8877..2288..  GGrraassss


        The ggrraassss terminal driver gives ggnnuupplloott capabilities to users
        of the GRASS geographic information system.  Contact grassp-
        list@moon.cecer.army.mil for more information.  Pages are










   GNUPLOT 4.1                                                      267


        written to the current frame of the GRASS Graphics Window.
        There are no options.



        8877..2299..  HHeerrccuulleess


        These drivers supports PC monitors with autodetected graphics
        boards.  They can be used only when compiled with Zortech
        C/C++.  None have options.



        8877..3300..  HHpp22662233aa


        The hhpp22662233aa terminal driver supports the Hewlett Packard
        HP2623A.  It has no options.



        8877..3311..  HHpp22664488


        The hhpp22664488 terminal driver supports the Hewlett Packard HP2647
        and HP2648.  It has no options.



        8877..3322..  HHpp550000cc


        The hhpp550000cc terminal driver supports the Hewlett Packard HP
        DeskJet 500c.  It has options for resolution and compression.

        Syntax:
              set terminal hp500c {<res>} {<comp>}

        where rreess can be 75, 100, 150 or 300 dots per inch and ccoommpp can
        be "rle", or "tiff".  Any other inputs are replaced by the
        defaults, which are 75 dpi and no compression.  Rasterization
        at the higher resolutions may require a large amount of memory.



        8877..3333..  HHppggll


        The hhppggll driver produces HPGL output for devices like the
        HP7475A plotter.  There are two options which can be set: the
        number of pens and eejjeecctt, which tells the plotter to eject a
        page when done.  The default is to use 6 pens and not to eject










   GNUPLOT 4.1                                                      268


        the page when done.

        The international character sets ISO-8859-1 and CP850 are rec-
        ognized via sseett eennccooddiinngg iissoo__88885599__11 or sseett eennccooddiinngg ccpp885500 (see
        sseett eennccooddiinngg for details).

        Syntax:
              set terminal hpgl {<number_of_pens>} {eject}

        The selection

              set terminal hpgl 8 eject

        is equivalent to the previous hhpp77555500 terminal, and the selec-
        tion

              set terminal hpgl 4

        is equivalent to the previous hhpp77558800bb terminal.

        The ppccll55 driver supports plotters such as the Hewlett-Packard
        Designjet 750C, the Hewlett-Packard Laserjet III, and the
        Hewlett-Packard Laserjet IV.  It actually uses HPGL-2, but
        there is a name conflict among the terminal devices.  It has
        several options which must be specified in the order indicated
        below:

        Syntax:
              set terminal pcl5 {mode <mode>} {<plotsize>}
                  {{color {<number_of_pens>}} | monochrome} {solid |
        dashed}
                  {font <font>} {size <fontsize>} {pspoints | nops-
        points}

        <mode> is llaannddssccaappee or ppoorrttrraaiitt. <plotsize> is the physical
        plotting size of the plot, which is one of the following: lleett--
        tteerr for standard (8 1/2" X 11") displays, lleeggaall for (8 1/2" X
        14") displays, nnooeexxtteennddeedd for (36" X 48") displays (a letter
        size ratio) or, eexxtteennddeedd for (36" X 55") displays (almost a
        legal size ratio).  ccoolloorr is for multi-pen (i.e. color) plots,
        and <number_of_pens> is the number of pens (i.e. colors) used
        in color plots. mmoonnoocchhrroommee is for one (e.g. black) pen plots.
        ssoolliidd draws all lines as solid lines, or ddaasshheedd will draw lines
        with different dashed and dotted line patterns.  <font> is
        ssttiicckk, uunniivveerrss, ccgg__ttiimmeess, zzaappff__ddiinnggbbaattss, aannttiiqquuee__oolliivvee, aarriiaall,
        ccoouurriieerr, ggaarraammoonndd__aannttiigguuaa, lleetttteerr__ggootthhiicc, ccgg__oommeeggaa, aallbbeerrttuuss,
        ttiimmeess__nneeww__rroommaann, ccllaarreennddoonn, ccoorroonneett, mmaarriiggoolldd, ttrruueettyyppee__ssyymm--
        bboollss, or wwiinnggddiinnggss. <fontsize> is the font size in points.  The
        point type selection can be the standard default set by speci-
        fying nnooppssppooiinnttss, or the same set of point types found in the
        postscript terminal by specifying ppssppooiinnttss.

        Note that built-in support of some of these options is printer










   GNUPLOT 4.1                                                      269


        device dependent. For instance, all the fonts are supposedly
        supported by the HP Laserjet IV, but only a few (e.g. univers,
        stick) may be supported by the HP Laserjet III and the Design-
        jet 750C. Also, color obviously won't work on the the laserjets
        since they are monochrome devices.

        Defaults: landscape, noextended, color (6 pens), solid,
        univers, 12 point,
                  and nopspoints.

        With ppccll55 international characters are handled by the printer;
        you just put the appropriate 8-bit character codes into the
        text strings.  You don't need to bother with sseett eennccooddiinngg.

        HPGL graphics can be imported by many software packages.



        8877..3344..  HHpplljjiiii


        The hhpplljjiiii terminal driver supports the HP Laserjet Series II
        printer.  The hhppddjj driver supports the HP DeskJet 500 printer.
        These drivers allow a choice of resolutions.

        Syntax:
              set terminal hpljii | hpdj {<res>}

        where rreess may be 75, 100, 150 or 300 dots per inch; the default
        is 75.  Rasterization at the higher resolutions may require a
        large amount of memory.

        The hhpp550000cc terminal is similar to hhppddjj; hhpp550000cc additionally
        supports color and compression.



        8877..3355..  HHppppjj


        The hhppppjj terminal driver supports the HP PaintJet and HP3630
        printers.  The only option is the choice of font.

        Syntax:
              set terminal hppj {FNT5X9 | FNT9X17 | FNT13X25}

        with the middle-sized font (FNT9X17) being the default.
















   GNUPLOT 4.1                                                      270


        8877..3366..  IImmaaggeenn


        The iimmaaggeenn terminal driver supports Imagen laser printers.  It
        is capable of placing multiple graphs on a single page.

        Syntax:
              set terminal imagen {<fontsize>} {portrait | landscape}
                                  {[<horiz>,<vert>]}

        where ffoonnttssiizzee defaults to 12 points and the layout defaults to
        llaannddssccaappee.  <<hhoorriizz>> and <<vveerrtt>> are the number of graphs in the
        horizontal and vertical directions; these default to unity.

        Example:
              set terminal imagen portrait [2,3]

        puts six graphs on the page in three rows of two in portrait
        orientation.



        8877..3377..  JJppeegg


        Syntax:
              set terminal jpeg
                     {{no}interlace}
                     {linewidth <lw>} {dashlength <dl>} {rounded|butt}
                     {tiny | small | medium | large | giant}
                     {font "<face> {,<pointsize>}"} {{no}enhanced}
                     {size <x>,<y>} {{no}crop}
                     {<background_color>}

        PNG, JPEG and GIF images are created using the external library
        libgd.  In most cases, PNG is to be preferred for single plots,
        and GIF for animations.  Both are loss-less image formats, and
        produce better image quality than the lossy JPEG format. This
        is in particular noticeable for solid color lines against a
        solid background, i.e. exactly the sort of image typically cre-
        ated by gnuplot.

        The iinntteerrllaaccee option creates a progressive JPEG image.  Default
        is nnooiinntteerrllaaccee.

        The lliinneewwiiddtthh and ddaasshhlleennggtthh options are scaling factors that
        affect all lines drawn, i.e. they are multiplied by values
        requested in various drawing commands.

        bbuutttt instructs the driver to use a line drawing method that
        does not overshoot the desired end point of a line.  This set-
        ting is only applicable for line widths greater than 1.  This
        setting is most useful when drawing horizontal or vertical










   GNUPLOT 4.1                                                      271


        lines.  Default is rroouunnddeedd.

        The details of font selection are complicated.  Two equivalent
        simple examples are given below:
             set term jpeg font arial 11
             set term jpeg font "arial,11"
        For more information please see the separate section under
        ffoonnttss.

        The output plot size <x,y> is given in pixels---it defaults to
        640x480.  Please see additional information under ccaannvvaass and
        sseett ssiizzee.  Blank space at the edges of the finished plot may be
        trimmed using the ccrroopp option, resulting in a smaller final
        image size. Default is nnooccrroopp.

        The background color must be given in the form 'xrrggbb', where
        x is the literal character 'x' and 'rrggbb' are the red, green
        and blue components in hexadecimal.  For example, 'x00ff00' is
        green.  The specification of additional colors other than the
        background is deprecated.




        8877..3388..  KKyyoo


        The kkyyoo and pprreessccrriibbee terminal drivers support the Kyocera
        laser printer.  The only difference between the two is that kkyyoo
        uses "Helvetica" whereas pprreessccrriibbee uses "Courier".  There are
        no options.



        8877..3399..  LLaatteexx


        Syntax:
              set terminal {latex | emtex} {default | {courier|roman}
        {<fontsize>}}
                           {size <XX>{unit}, <YY>{unit}} {rotate |
        norotate}

        By default the plot will inherit font settings from the embed-
        ding document.  You have the option of forcing either Courier
        (cmtt) or Roman (cmr) fonts instead. In this case you may also
        specify a fontsize.  Unless your driver is capable of building
        fonts at any size (e.g. dvips), stick to the standard 10, 11
        and 12 point sizes.

        METAFONT users beware: METAFONT does not like odd sizes.

        All drivers for LaTeX offer a special way of controlling text










   GNUPLOT 4.1                                                      272


        positioning: If any text string begins with '{', you also need
        to include a '}' at the end of the text, and the whole text
        will be centered both horizontally and vertically.  If the text
        string begins with '[', you need to follow this with a position
        specification (up to two out of t,b,l,r), ']{', the text
        itself, and finally '}'.  The text itself may be anything LaTeX
        can typeset as an LR-box.  '\rule{}{}'s may help for best posi-
        tioning.

        Points, among other things, are drawn using the LaTeX commands
        "\Diamond" and "\Box".  These commands no longer belong to the
        LaTeX2e core; they are included in the latexsym package, which
        is part of the base distribution and thus part of any LaTeX
        implementation.  Please do not forget to use this package.
        Other point types use symbols from the amssymb package.

        The default size for the plot is 5 inches by 3 inches. The ssiizzee
        option changes this to whatever the user requests. By default
        the X and Y sizes are taken to be in inches, but other units
        are possible (currently only cm).

        If 'rotate' is specified, rotated text, especially a rotated y-
        axis label, is possible (the packages graphics or graphicx are
        needed). The 'stacked' y-axis label mechanism is then deacti-
        vated.

        Examples: About label positioning: Use gnuplot defaults (mostly
        sensible, but sometimes not really best):
               set title '\LaTeX\ -- $ \gamma $'
        Force centering both horizontally and vertically:
               set label '{\LaTeX\ -- $ \gamma $}' at 0,0
        Specify own positioning (top here):
               set xlabel '[t]{\LaTeX\ -- $ \gamma $}'
        The other label -- account for long ticlabels:
               set ylabel '[r]{\LaTeX\ -- $ \gamma $\rule{7mm}{0pt}}'



        8877..4400..  LLiinnuuxx


        The lliinnuuxx driver has no additional options to specify.  It
        looks at the environment variable GSVGAMODE for the default
        mode; if not set, it uses 1024x768x256 as default mode or, if
        that is not possible, 640x480x16 (standard VGA).



        8877..4411..  LLuuaa


        The lluuaa generic terminal driver works in conjunction with an
        external Lua script to create a target-specific plot file.










   GNUPLOT 4.1                                                      273


        Currently the only supported target is TikZ -> pdflatex.

        Information about Lua is available at http://www.lua.org .

        Syntax:
           set terminal lua <target name> | "<file name>"
                               {<script_args> ...}
                               {help}

        A 'target name' or 'file name' (in quotes) for a script is
        mandatory.  If a 'target name' for the script is given, the
        terminal will look for "gnuplot-<target name>.lua" in the local
        directory and on failure in the environmental variable GNU-
        PLOT_LUA_DIR.

        All arguments will be provided to the selected script for fur-
        ther evaluation. E.g. 'set term lua tikz help' will cause the
        script itself to print additional help on options and choices
        for the script.

        The TikZ driver provides the following additional terminal
        options:

             {help}
             {monochrome}
             {solid}
             {originreset}
             {gparrows}
             {gppoints}
             {nopicenvironment}
             {size <x>{unit},<y>{unit}}
             {scale <x>,<y>}
             {plotsize <x>{unit},<y>{unit}}
             {charsize <x>{unit},<y>{unit}}
             {font "<fontdesc>"}
             {createstyle}
             {fulldoc|standalone}
             {{preamble|header} "<preamble_string>"}
             {tikzplot <ltn>,...}
             {tikzarrows}
             {cmykimages}
             {nobitmap}
             {providevars <var name>,...}

        For all options that expect lengths as their arguments they
        will default to 'cm' if no unit is specified. For all lengths
        the following units may be used: 'cm', 'mm', 'in' or 'inch',
        'pt', 'pc', 'bp', 'dd', 'cc'. Blanks between numbers and units
        are not allowed.

        'monochrome' disables line coloring and switches to grayscaled
        fills.











   GNUPLOT 4.1                                                      274


        'solid' use only solid lines.

        'originreset' moves the origin of the TikZ picture to the lower
        left corner of the plot. It may be used to align several plots
        within one tikzpicture environment. This is not tested with
        multiplots and pm3d plots!

        'gparrows' use gnuplot's internal arrow drawing function
        instead of the ones provided by TikZ.

        'gppoints' use gnuplot's internal plotmark drawing function
        instead of the ones provided by TikZ.

        'nopicenvironment' omits the declaration of the 'tikzpicture'
        environment in order to set it manually. This permits putting
        some PGF/TikZ code directly before or after the plot.

        The 'size' option expects two lenghts <x> and <y> as the canvas
        size.  The default size of the canvas is 12.5cm x 8.75cm.

        The 'scale' option works similar to the 'size' option but
        expects scaling factors <x> and <y> instead of lengths.

        The 'plotsize' option permits setting the size of the plot area
        instead of the canvas size, which is the usual gnuplot behav-
        iour.  Using this option may lead to slightly asymmetric tic
        lengths.  Like 'originreset' this option may not lead to conve-
        nient results if used with multiplots or pm3d plots.

        The 'charsize' option expects the average horizontal and verti-
        cal size of the used font. Look at the generated style file for
        an example of how to use it from within your TeX document.

        'createstyle' derives the LaTeX style file from the script and
        writes it to the file 'gnuplot-lua-tikz.sty'.

        'fulldoc' or 'standalone' produces a full LaTeX document for
        direct compilation.

        'preamble' or 'header' may be used to put any additional LaTeX
        code into the document preamble in standalone mode.

        With the 'tikzplot' option the '\path plot' command will be
        used instead of only '\path'. The following list of numbers of
        linetypes (<ltn>,...) defines the affected plotlines. There
        exists a plotstyle for every linetype. The default plotstyle is
        'smooth' for every linetype >= 1.

        By using the 'tikzarrows' option the gnuplot arrow styles
        defined by the user will be mapped to TikZ arrow styles. This
        is done by 'misusing' the angle value of the arrow definition.
        E.g. an arrow style with the angle '7' will be mapped to the
        TikZ style 'gp arrow 7' ignoring all the other given values. By










   GNUPLOT 4.1                                                      275


        default the TikZ terminal uses the stealth' arrow tips for all
        arrows. To obtain the default gnuplot behaviour please use the
        'gparrows' option.

        With 'cmykimages' the CMYK color model will be used for image
        data instead of the RGB model. All other colors (like line col-
        ors etc.) are not affected by this option, since they are han-
        dled by the xcolors package. So take care to change the color
        model also there if needed.

        The 'nobitmap' option let images be rendered as filled rectan-
        gles instead of the nativ PS or PDF image format. This option
        has to be enabled if you intend to use other output formats.

        The 'providevars' options makes gnuplot's internal and user
        variables available by using the '\gpgetvar{<var name>}' comm-
        mand within the TeX script. Use gnuplot's 'show variables all'
        command to see the list of valid variables.

        The <fontdesc> string may contain any valid LaTeX font commands
        like e.g. '\small'. It is passed directly as a node parameter
        in form of "font=<fontdesc>". This can be 'misused' to add fur-
        ther code to a node, e.g. '\small,yshift=1ex' or ',yshift=1ex'
        are also valid while the latter does not change the current
        font settings. One exception is the second argument of the
        list. If it is a number of the form <number>{unit} it will be
        interpreted as a fontsize like in other terminals and will be
        appended to the first argument. If the unit is omitted the
        value is interpreted as 'pt'. As an example the string '\sffam-
        ily,12,fill=red' sets the font to LaTeX's sans serif font at a
        size of 12pt and red background color.

        Strings have to be put in single or double quotes. Double
        quoted strings may contain special characters like newlines
        '\n' etc.




        8877..4422..  MMaacciinnttoosshh


        Syntax:
             set terminal macintosh {singlewin | multiwin} {vertical |
        novertical}
                                    {size <width>, <height> | default}

        'singlewin' limits the output to a single window and is useful
        for animations.  'multiwin' allows multiple windows.  'verti-
        cal' is only valid under the gx option. With this option,
        rotated text will be drawn vertically. novertical turns this
        option off.  size <width>, <height> overrides the graph size
        set in the preferences dialog until it is cleared with either










   GNUPLOT 4.1                                                      276


        'set term mac size default' or 'set term mac default'.

        'set term mac size default' sets the window size settings to
        those set in the preferences dialog.

        'set term mac default' sets all options to their default val-
        ues.  Default values: nogx, multiwin, novertical.

        If you generate graphs under the multiwin option and then
        switch to singlewin, the next plot command will cause one more
        window to be created. This new window will be reused as long as
        singlewin is in effect. If you switch back to multiwin, gener-
        ate some graphs, and then switch to singlewin again, the
        orginal 'singlewin' window will be resused if it is still open.
        Otherwise a new 'singlewin' window will be created. The 'sin-
        glewin' window is not numbered.



        8877..4433..  MMff


        The mmff terminal driver creates an input file to the METAFONT
        program.  Thus a figure may be used in the TeX document in the
        same way as is a character.

        To use a picture in a document, the METAFONT program must be
        run with the output file from ggnnuupplloott as input.  Thus, the user
        needs a basic knowledge of the font creating process and the
        procedure for including a new font in a document.  However, if
        the METAFONT program is set up properly at the local site, an
        unexperienced user could perform the operation without much
        trouble.

        The text support is based on a METAFONT character set.  Cur-
        rently the Computer Modern Roman font set is input, but the
        user is in principal free to choose whatever fonts he or she
        needs.  The METAFONT source files for the chosen font must be
        available.  Each character is stored in a separate picture
        variable in METAFONT.  These variables may be manipulated
        (rotated, scaled etc.) when characters are needed.  The draw-
        back is the interpretation time in the METAFONT program.  On
        some machines (i.e. PC) the limited amount of memory available
        may also cause problems if too many pictures are stored.

        The mmff terminal has no options.

















   GNUPLOT 4.1                                                      277


             8877..4433..11..  MMEETTAAFFOONNTT IInnssttrruuccttiioonnss



             - Set your terminal to METAFONT:
               set terminal mf
             - Select an output-file, e.g.:
               set output "myfigures.mf"
             - Create your pictures. Each picture will generate a sepa-
             rate character. Its default size will be 5*3 inches. You
             can change the size by saying sseett ssiizzee 00..55,,00..55 or whatever
             fraction of the default size you want to have.

             - Quit ggnnuupplloott.

             - Generate a TFM and GF file by running METAFONT on the
             output of ggnnuupplloott.  Since the picture is quite large (5*3
             in), you will have to use a version of METAFONT that has a
             value of at least 150000 for memmax.  On Unix systems
             these are conventionally installed under the name bigmf.
             For the following assume that the command virmf stands for
             a big version of METAFONT.  For example:

             - Invoke METAFONT:
                 virmf '&plain'
             - Select the output device: At the METAFONT prompt ('*')
             type:
                 \mode:=CanonCX;     % or whatever printer you use
             - Optionally select a magnification:
                 mag:=1;             % or whatever you wish
             - Input the ggnnuupplloott-file:
                 input myfigures.mf
             On a typical Unix machine there will usually be a script
             called "mf" that executes virmf '&plain', so you probably
             can substitute mf for virmf &plain.  This will generate
             two files: mfput.tfm and mfput.$$$gf (where $$$ indicates
             the resolution of your device).  The above can be conve-
             niently achieved by typing everything on the command line,
             e.g.: virmf '&plain' '\mode:=CanonCX; mag:=1; input myfig-
             ures.mf' In this case the output files will be named
             myfigures.tfm and myfigures.300gf.

             - Generate a PK file from the GF file using gftopk:
               gftopk myfigures.300gf myfigures.300pk
             The name of the output file for gftopk depends on the DVI
             driver you use.  Ask your local TeX administrator about
             the naming conventions.  Next, either install the TFM and
             PK files in the appropriate directories, or set your envi-
             ronment variables properly.  Usually this involves setting
             TEXFONTS to include the current directory and doing the
             same thing for the environment variable that your DVI
             driver uses (no standard name here...).  This step is nec-
             essary so that TeX will find the font metric file and your










   GNUPLOT 4.1                                                      278


             DVI driver will find the PK file.

             - To include your pictures in your document you have to
             tell TeX the font:
               \font\gnufigs=myfigures
             Each picture you made is stored in a single character.
             The first picture is character 0, the second is character
             1, and so on...  After doing the above step, you can use
             the pictures just like any other characters.  Therefore,
             to place pictures 1 and 2 centered in your document, all
             you have to do is:
               \centerline{\gnufigs\char0}
               \centerline{\gnufigs\char1}
             in plain TeX.  For LaTeX you can, of course, use the pic-
             ture environment and place the picture wherever you wish
             by using the \makebox and \put macros.

             This conversion saves you a lot of time once you have gen-
             erated the font; TeX handles the pictures as characters
             and uses minimal time to place them, and the documents you
             make change more often than the pictures do.  It also
             saves a lot of TeX memory.  One last advantage of using
             the METAFONT driver is that the DVI file really remains
             device independent, because no \special commands are used
             as in the eepic and tpic drivers.



        8877..4444..  MMggrr


        The mmggrr terminal driver supports the Mgr Window system.  It has
        no options.



        8877..4455..  MMiiff


        The mmiiff terminal driver produces Frame Maker MIF format version
        3.00.  It plots in MIF Frames with the size 15*10 cm, and plot
        primitives with the same pen will be grouped in the same MIF
        group.  Plot primitives in a ggnnuupplloott page will be plotted in a
        MIF Frame, and several MIF Frames are collected in one large
        MIF Frame.  The MIF font used for text is "Times".

        Several options may be set in the MIF 3.00 driver.

        Syntax:
              set terminal mif {color | colour | monochrome} {polyline
        | vectors}
                               {help | ?}











   GNUPLOT 4.1                                                      279


        ccoolloouurr plots lines with line types >= 0 in colour (MIF sep.
        2--7) and mmoonnoocchhrroommee plots all line types in black (MIF sep.
        0).  ppoollyylliinnee plots curves as continuous curves and vveeccttoorrss
        plots curves as collections of vectors.  hheellpp and ?? print
        online help on standard error output---both print a short
        description of the usage; hheellpp also lists the options.

        Examples:
              set term mif colour polylines    # defaults
              set term mif                     # defaults
              set term mif vectors
              set term mif help



        8877..4466..  MMpp



        The mmpp driver produces output intended to be input to the Meta-
        post program.  Running Metapost on the file creates EPS files
        containing the plots. By default, Metapost passes all text
        through TeX.  This has the advantage of allowing essentially
        any TeX symbols in titles and labels.

        Syntax:
           set term mp {color | colour | monochrome}
                       {solid | dashed}
                       {notex | tex | latex}
                       {magnification <magsize>}
                       {psnfss | psnfss-version7 | nopsnfss}
                       {prologues <value>}
                       {a4paper}
                       {amstex}
                       {"<fontname>"} {<fontsize>}

        The option ccoolloorr causes lines to be drawn in color (on a
        printer or display that supports it), mmoonnoocchhrroommee (or nothing)
        selects black lines.  The option ssoolliidd draws solid lines, while
        ddaasshheedd (or nothing) selects lines with different patterns of
        dashes.  If ssoolliidd is selected but ccoolloorr is not, nearly all
        lines will be identical.  This may occasionally be useful, so
        it is allowed.

        The option nnootteexx bypasses TeX entirely, therefore no TeX code
        can be used in labels under this option.  This is intended for
        use on old plot files or files that make frequent use of common
        characters like $$ and %% that require special handling in TeX.

        The option tteexx sets the terminal to output its text for TeX to
        process.

        The option llaatteexx sets the terminal to output its text for










   GNUPLOT 4.1                                                      280


        processing by LaTeX. This allows things like \frac for frac-
        tions which LaTeX knows about but TeX does not.  Note that you
        must set the environment variable TEX to the name of your LaTeX
        executable (normally latex) if you use this option or use mmppoosstt
        ----tteexx==<<nnaammee ooff LLaaTTeeXX eexxeeccuuttaabbllee>> ....... Otherwise metapost will
        try and use TeX to process the text and it won't work.

        Changing font sizes in TeX has no effect on the size of mathe-
        matics, and there is no foolproof way to make such a change,
        except by globally  setting a magnification factor. This is the
        purpose of the mmaaggnniiffiiccaattiioonn option. It must be followed by a
        scaling factor. All text (NOT the graphs) will be scaled by
        this factor. Use this if you have math that you want at some
        size other than the default 10pt. Unfortunately, all math will
        be the same size, but see the discussion below on editing the
        MP output. mmaagg will also work under nnootteexx but there seems no
        point in using it as the font size option (below) works as
        well.

        The option ppssnnffssss uses postscript fonts in combination with
        LaTeX. Since this option only makes sense, if LaTeX is being
        used, the llaatteexx option is selected automatically. This option
        includes the following packages for LaTeX: inputenc(latin1),
        fontenc(T1), mathptmx, helvet(scaled=09.2), courier, latexsym
        and textcomp.

        The option ppssnnffssss--vveerrssiioonn77 uses also postscript fonts in LaTeX
        (option llaatteexx is also automatically selected), but uses the
        following packages with LaTeX: inputenc(latin1), fontenc(T1),
        times, mathptmx, helvet and courier.

        The option nnooppssnnffssss is the default and uses the standard font
        (cmr10 if not otherwise specified).

        The option pprroolloogguueess takes a value as an additional argument
        and adds the line pprroolloogguueess::==<<vvaalluuee>> to the metapost file. If a
        value of 22 is specified metapost uses postscript fonts to gen-
        erate the eps-file, so that the result can be viewed using e.g.
        ghostscript. Normally the output of metapost uses TeX fonts and
        therefore has to be included in a (La)TeX file before you can
        look at it.

        The option nnoopprroolloogguueess is the default. No additional line spec-
        ifying the prologue will be added.

        The option aa44ppaappeerr adds a [[aa44ppaappeerr]] to the documentclass. Nor-
        mally letter paper is used (default). Since this option is only
        used in case of LaTeX, the llaatteexx option is selected automati-
        cally.

        The option aammsstteexx automatically selects the llaatteexx option and
        includes the following LaTeX packages: amsfonts, ams-
        math(intlimits). By default these packages are not included.










   GNUPLOT 4.1                                                      281


        A name in quotes selects the font that will be used when no
        explicit font is given in a sseett llaabbeell or sseett ttiittllee.  A name
        recognized by TeX (a TFM file exists) must be used.  The
        default is "cmr10" unless nnootteexx is selected, then it is
        "pcrr8r" (Courier).  Even under nnootteexx, a TFM file is needed by
        Metapost. The file ppccrrrr88rr..ttffmm is the name given to Courier in
        LaTeX's psnfss package.  If you change the font from the nnootteexx
        default, choose a font that matches the ASCII encoding at least
        in the range 32-126.  ccmmtttt1100 almost works, but it has a non-
        blank character in position 32 (space).

        The size can be any number between 5.0 and 99.99.  If it is
        omitted, 10.0 is used.  It is advisable to use mmaaggsstteepp sizes:
        10 times an integer or half-integer power of 1.2, rounded to
        two decimals, because those are the most available sizes of
        fonts in TeX systems.

        All the options are optional.  If font information is given, it
        must be at the end, with size (if present) last.  The size is
        needed to select a size for the font, even if the font name
        includes size information.  For example, sseett tteerrmm mmpp ""ccmmtttt1122""
        selects cmtt12 shrunk to the default size 10.  This is probably
        not what you want or you would have used cmtt10.

        The following common ascii characters need special treatment in
        TeX:
           $, &, #, %, _;  |, <, >;  ^, ~,  \, {, and }
        The five characters $, #, &, _, and % can simply be escaped,
        e.g., \\$$.  The three characters <, >, and | can be wrapped in
        math mode, e.g., $$<<$$.  The remainder require some TeX work-
        arounds.  Any good book on TeX will give some guidance.

        If you type your labels inside double quotes, backslashes in
        TeX code need to be escaped (doubled). Using single quotes will
        avoid having to do this, but then you cannot use \\nn for line
        breaks.  As of this writing, version 3.7 of gnuplot processes
        titles given in a pplloott command differently than in other
        places, and backslashes in TeX commands need to be doubled
        regardless of the style of quotes.

        Metapost pictures are typically used in TeX documents.  Meta-
        post deals with fonts pretty much the same way TeX does, which
        is different from most other document preparation programs.  If
        the picture is included in a LaTeX document using the graphics
        package, or in a plainTeX document via epsf.tex, and then con-
        verted to PostScript with dvips (or other dvi-to-ps converter),
        the text in the plot will usually be handled correctly.  How-
        ever, the text may not appear if you send the Metapost output
        as-is to a PostScript interpreter.














   GNUPLOT 4.1                                                      282


             8877..4466..11..  MMeettaappoosstt IInnssttrruuccttiioonnss



             - Set your terminal to Metapost, e.g.:
                set terminal mp mono "cmtt12" 12

             - Select an output-file, e.g.:
                set output "figure.mp"

             - Create your pictures.  Each plot (or multiplot group)
             will generate a separate Metapost beginfig...endfig group.
             Its default size will be 5 by 3 inches.  You can change
             the size by saying sseett ssiizzee 00..55,,00..55 or whatever fraction
             of the default size you want to have.

             - Quit gnuplot.

             - Generate EPS files by running Metapost on the output of
             gnuplot:
                mpost figure.mp  OR  mp figure.mp
             The name of the Metapost program depends on the system,
             typically mmppoosstt for a Unix machine and mmpp on many others.
             Metapost will generate one EPS file for each picture.

             - To include your pictures in your document you can use
             the graphics package in LaTeX or epsf.tex in plainTeX:
                \usepackage{graphics} % LaTeX
                \input epsf.tex       % plainTeX
             If you use a driver other than dvips for converting TeX
             DVI output to PS, you may need to add the following line
             in your LaTeX document:
                \DeclareGraphicsRule{*}{eps}{*}{}
             Each picture you made is in a separate file.  The first
             picture is in, e.g., figure.0, the second in figure.1, and
             so on....  To place the third picture in your document,
             for example, all you have to do is:
                \includegraphics{figure.2} % LaTeX
                \epsfbox{figure.2}         % plainTeX

             The advantage, if any, of the mp terminal over a post-
             script terminal is editable output.  Considerable effort
             went into making this output as clean as possible.  For
             those knowledgeable in the Metapost language, the default
             line types and colors can be changed by editing the arrays
             lltt[[]] and ccooll[[]].  The choice of solid vs dashed lines, and
             color vs black lines can be change by changing the values
             assigned to the booleans ddaasshheeddlliinneess and ccoolloorrlliinneess.  If
             the default tteexx option was in effect, global changes to
             the text of labels can be achieved by editing the vveebbaattiimm--
             tteexx......eetteexx block.  In particular, a LaTeX preamble can be
             added if desired, and then LaTeX's built-in size changing
             commands can be used for maximum flexibility. Be sure to










   GNUPLOT 4.1                                                      283


             set the appropriate MP configuration variable to force
             Metapost to run LaTeX instead of plainTeX.



        8877..4477..  NNeexxtt


        Several options may be set in the next driver.

        Syntax:
              set terminal next {<mode>} {<type> } {<color>} {<dashed>}
                         {"<fontname>"} {<fontsize>} title {"<newti-
        tle>"}

        where <mode> is  ddeeffaauulltt, which sets all options to their
        defaults; <type> is either nneeww or oolldd, where oolldd invokes the
        old single window; <color> is either ccoolloorr or mmoonnoocchhrroommee;
        <dashed> is either ssoolliidd or ddaasshheedd; "<fontname>" is the name of
        a valid PostScript font; <fontsize> is the size of the font in
        PostScript points; and <title> is the title for the GnuTerm
        window.  Defaults are  nneeww, mmoonnoocchhrroommee, ddaasshheedd, "Helvetica",
        14pt.

        Examples:
              set term next default
              set term next 22
              set term next color "Times-Roman" 14
              set term next color "Helvetica" 12 title "MyPlot"
              set term next old

        Pointsizes may be changed with sseett lliinneessttyyllee.



        8877..4488..  OOppeennsstteepp ((nneexxtt))


        Several options may be set in the openstep (next) driver.

        Syntax:
              set terminal openstep {<mode>} {<type> } {<color>}
        {<dashed>}
                         {"<fontname>"} {<fontsize>} title {"<newti-
        tle>"}

        where <mode> is  ddeeffaauulltt, which sets all options to their
        defaults; <type> is either nneeww or oolldd, where oolldd invokes the
        old single window; <color> is either ccoolloorr or mmoonnoocchhrroommee;
        <dashed> is either ssoolliidd or ddaasshheedd; "<fontname>" is the name of
        a valid PostScript font; <fontsize> is the size of the font in
        PostScript points; and <title> is the title for the GnuTerm
        window.  Defaults are  nneeww, mmoonnoocchhrroommee, ddaasshheedd, "Helvetica",










   GNUPLOT 4.1                                                      284


        14pt.

        Examples:
              set term openstep default
              set term openstep 22
              set term openstep color "Times-Roman" 14
              set term openstep color "Helvetica" 12 title "MyPlot"
              set term openstep old

        Pointsizes may be changed with sseett lliinneessttyyllee.



        8877..4499..  PPbbmm


        Syntax:
              set terminal pbm {<fontsize>} {<mode>} {size <x>,<y>}

        where <fontsize> is ssmmaallll, mmeeddiiuumm, or llaarrggee and <mode> is mmoonnoo--
        cchhrroommee, ggrraayy or ccoolloorr.  The default plot size is 640 pixels
        wide and 480 pixels high. The output size is white-space padded
        to the nearest multiple of 8 pixels on both x and y. This empty
        space may be cropped later if needed.

        The output of the ppbbmm driver depends upon <mode>: mmoonnoocchhrroommee
        produces a portable bitmap (one bit per pixel), ggrraayy a portable
        graymap (three bits per pixel) and ccoolloorr a portable pixmap
        (color, four bits per pixel).

        The output of this driver can be used with various image con-
        version and manipulation utilities provided by NETPBM.  Based
        on Jef Poskanzer's PBMPLUS package, NETPBM provides programs to
        convert the above PBM formats to GIF, TIFF, MacPaint, Macintosh
        PICT, PCX, X11 bitmap and many others.  Complete information is
        available at http://netpbm.sourceforge.net/.

        Examples:
              set terminal pbm small monochrome                #
        defaults
              set terminal pbm color medium size 800,600
              set output '| pnmrotate 45 | pnmtopng > tilted.png'  #
        uses NETPBM



        8877..5500..  PPddff


        This terminal produces files in the Adobe Portable Document
        Format (PDF), useable for printing or display with tools like
        Acrobat Reader











   GNUPLOT 4.1                                                      285


        Syntax:
              set terminal pdf {monochrome|color|colour}
                               {{no}enhanced}
                               {fname "<font>"} {fsize <fontsize>}
                               {font "<fontname>{,<fontsize>}"}
                               {linewidth <lw>} {rounded|butt}
                               {solid|dashed} {dl <dashlength>}}
                               {size <XX>{unit},<YY>{unit}}

        The default is to use a different color for each line type.
        Selecting mmoonnoocchhoommee will use black for all linetypes, in which
        case you probably want to select ddaasshheedd to distinguish line
        types. Even in in mono mode you can still use explicit colors
        for filled areas or linestyles.

        where <font> is the name of the default font to use (default
        Helvetica) and <fontsize> is the font size (in points, default
        12).  For help on which fonts are available or how to install
        new ones, please see the documentation for your local installa-
        tion of pdflib.

        The eennhhaanncceedd option enables enhanced text processing features
        (subscripts, superscripts and mixed fonts). See eennhhaanncceedd.

        The width of all lines in the plot can be increased by the fac-
        tor <n> specified in lliinneewwiiddtthh. Similarly ddaasshhlleennggtthh is a mul-
        tiplier for the default dash spacing.

        rroouunnddeedd sets line caps and line joins to be rounded; bbuutttt is
        the default, butt caps and mitered joins.

        The default size for PDF output is 5 inches by 3 inches. The
        ssiizzee option changes this to whatever the user requests. By
        default the X and Y sizes are taken to be in inches, but other
        units are possible (currently only cm).




        8877..5511..  PPddffccaaiirroo


        The ppddffccaaiirroo terminal device generates output in pdf. The
        actual drawing is done via cairo, a 2D graphics library, and
        pango, a library for laying out and rendering text.

        Syntax:
                set term pdfcairo
                             {{no}enhanced} {mono|color} {solid|dashed}
                             {font <font>}
                             {linewidth <lw>} {rounded|butt} {dash-
        length <dl>}
                             {size <XX>{unit},<YY>{unit}}










   GNUPLOT 4.1                                                      286


        This terminal supports an enhanced text mode, which allows font
        and other formatting commands (subscripts, superscripts, etc.)
        to be embedded in labels and other text strings. The enhanced
        text mode syntax is shared with other gnuplot terminal types.
        See eennhhaanncceedd for more details.

        The width of all lines in the plot can be modified by the fac-
        tor <lw> specified in lliinneewwiiddtthh. The default linewidth is 0.25
        points.  (1 "PostScript" point = 1/72 inch = 0.353 mm)

        rroouunnddeedd sets line caps and line joins to be rounded; bbuutttt is
        the default, butt caps and mitered joins.

        The default size for the output is 5 inches x 3 inches. The
        ssiizzee option changes this to whatever the user requests. By
        default the X and Y sizes are taken to be in inches, but other
        units are possibly (currently only cm).  Screen coordinates
        always run from 0.0 to 1.0 along the full length of the plot
        edges as specified by the ssiizzee option.

        <font> is in the format "FontFace,FontSize", i.e. the face and
        the size comma-separated in a single string. FontFace is a
        usual font face name, such as 'Arial'. If you do not provide
        FontFace, the pdfcairo terminal will use 'Sans'. FontSize is
        the font size, in points. If you do not provide it, the pdf-
        cairo terminal will use a size of 6 points.
           For example :
              set term pdfcairo font "Arial,12"
              set term pdfcairo font "Arial" # to change the font face
        only
              set term pdfcairo font ",12" # to change the font size
        only
              set term pdfcairo font "" # to reset the font name and
        size

        The fonts are retrieved from the usual fonts subsystems. Under
        Windows, those fonts are to be found and configured in the
        entry "Fonts" of the control panel. Under UNIX, they are han-
        dled by "fontconfig".

        Pango, the library used to layout the text, is based on utf-8.
        Thus, the pdfcairo terminal has to convert from your encoding
        to utf-8. The default input encoding is based on your 'locale'.
        If you want to use another encoding, make sure gnuplot knows
        which one you are using. See eennccooddiinngg for more details.

        Pango may give unexpected results with fonts that do not
        respect the unicode mapping. With the Symbol font, for example,
        the pdfcairo terminal will use the map provided by
        http://www.unicode.org/ to translate character codes to uni-
        code.  Note that "the Symbol font" is to be understood as the
        Adobe Symbol font, distributed with Acrobat Reader as
        "SY______.PFB".  Alternatively, the OpenSymbol font,










   GNUPLOT 4.1                                                      287


        distributed with OpenOffice.org as "opens___.ttf", offers the
        same characters. Microsoft has distributed a Symbol font ("sym-
        bol.ttf"), but it has a different character set with several
        missing or moved mathematic characters. If you experience prob-
        lems with your default setup (if the demo enhancedtext.dem is
        not displayed properly for example), you probably have to
        install one of the Adobe or OpenOffice Symbol fonts, and remove
        the Microsoft one.  Other non-conform fonts, such as
        "wingdings" have been observed working.

        The rendering of the plot cannot be altered yet. To obtain the
        best output possible, the rendering involves two mechanisms :
        antialiasing and oversampling.  Antialiasing allows to display
        non-horizontal and non-vertical lines smoother.  Oversampling
        combined with antialiasing provides subpixel accuracy, so that
        gnuplot can draw a line from non-integer coordinates. This
        avoids wobbling effects on diagonal lines ('plot x' for exam-
        ple).




        8877..5522..  PPmm


        The ppmm terminal driver provides an OS/2 Presentation Manager
        window in which the graph is plotted.  The window is opened
        when the first graph is plotted.  This window has its own
        online help as well as facilities for printing, copying to the
        clipboard and some line type and color adjustments.  The mmuullttii--
        pplloott option is supported.

        Syntax:
              set terminal pm {server {n}} {persist} {widelines}
        {enhanced} {"title"}

        If ppeerrssiisstt is specified, each graph appears in its own window
        and all windows remain open after ggnnuupplloott exits.  If sseerrvveerr is
        specified, all graphs appear in the same window, which remains
        open when ggnnuupplloott exits.  This option takes an optional numeri-
        cal argument which specifies an instance of the server process.
        Thus multiple server windows can be in use at the same time.

        If wwiiddeelliinneess is specified, all plots will be drawn with wide
        lines.  If eennhhaanncceedd is specified, sub- and superscripts and
        multiple fonts are enabled (see eennhhaanncceedd tteexxtt for details).
        Font names for the core PostScript fonts may be abbreviated to
        a single letter (T/H/C/S for Times/Helvetica/Courier/Symbol).

        If ttiittllee is specified, it will be used as the title of the plot
        window.  It will also be used as the name of the server
        instance, and will override the optional numerical argument.











   GNUPLOT 4.1                                                      288


        Linewidths may be changed with sseett lliinneessttyyllee.



        8877..5533..  PPnngg


        Syntax:
              set terminal png
                     {{no}transparent} {{no}interlace}
                     {{no}truecolor} {rounded|butt}
                     {linewidth <lw>} {dashlength <dl>}
                     {tiny | small | medium | large | giant}
                     {font "<face> {,<pointsize>}"} {{no}enhanced}
                     {size <x>,<y>} {{no}crop}
                     {<background_color>}

        PNG, JPEG and GIF images are created using the external library
        libgd.  PNG plots may be viewed interactively by piping the
        output to the 'display' program from the ImageMagick package as
        follows:
                       set term png
                       set output '| display png:-'
        You can view the output from successive plot commands interac-
        tively by typing <space> in the display window.  To save the
        current plot to a file, left click in the display window and
        choose ssaavvee.

        ttrraannssppaarreenntt instructs the driver to make the background color
        transparent.  Default is nnoottrraannssppaarreenntt.

        iinntteerrllaaccee instructs the driver to generate interlaced PNGs.
        Default is nnooiinntteerrllaaccee.

        The lliinneewwiiddtthh and ddaasshhlleennggtthh options are scaling factors that
        affect all lines drawn, i.e. they are multiplied by values
        requested in various drawing commands.

        By default output png images use 256 indexed colors. The ttrruuee--
        ccoolloorr option instead creates TrueColor images with 24 bits of
        color information per pixel.  Transparent fill styles require
        the ttrruueeccoolloorr option. See ffiillllssttyyllee.  A transparent background
        is possible in either indexed or TrueColor images.

        bbuutttt instructs the driver to use a line drawing method that
        does not overshoot the desired end point of a line.  This set-
        ting is only applicable for line widths greater than 1.  This
        setting is most useful when drawing horizontal or vertical
        lines.  Default is rroouunnddeedd.

        The details of font selection are complicated.  Two equivalent
        simple examples are given below:
             set term png font arial 11










   GNUPLOT 4.1                                                      289


             set term png font "arial,11"
        For more information please see the separate section under
        ffoonnttss.

        The output plot size <x,y> is given in pixels---it defaults to
        640x480.  Please see additional information under ccaannvvaass and
        sseett ssiizzee.  Blank space at the edges of the finished plot may be
        trimmed using the ccrroopp option, resulting in a smaller final
        image size. Default is nnooccrroopp.

        The background color must be given in the form 'xrrggbb', where
        x is the literal character 'x' and 'rrggbb' are the red, green
        and blue components in hexadecimal.  For example, 'x00ff00' is
        green.  The specification of additional colors other than the
        background is deprecated.





             8877..5533..11..  EExxaammpplleess


                   set terminal png medium size 640,480 xffffff

             Use the medium size built-in non-scaleable, non-rotatable
             font.  Use white (xffffff) for the non-transparent back-
             ground.

                   set terminal png font arial 14 size 800,600

             Searches for a scalable font with face name 'arial' and
             sets the font size to 14pt.  Please see ffoonnttss for details
             of how the font search is done.

                   set terminal png transparent truecolor enhanced

             Use 24 bits of color information per pixel, with a trans-
             parent background.  Use the eennhhaanncceedd tteexxtt mode to control
             the layout of strings to be printed.




        8877..5544..  PPnnggccaaiirroo


        The ppnnggccaaiirroo terminal device generates output in png. The
        actual drawing is done via cairo, a 2D graphics library, and
        pango, a library for laying out and rendering text.

        Syntax:
                set term pngcairo










   GNUPLOT 4.1                                                      290


                             {{no}enhanced} {mono|color} {solid|dashed}
                             {{no}transparent} {{no}crop} {font <font>}
                             {linewidth <lw>} {rounded|butt} {dash-
        length <dl>}
                             {size <XX>{unit},<YY>{unit}}

        This terminal supports an enhanced text mode, which allows font
        and other formatting commands (subscripts, superscripts, etc.)
        to be embedded in labels and other text strings. The enhanced
        text mode syntax is shared with other gnuplot terminal types.
        See eennhhaanncceedd for more details.

        The width of all lines in the plot can be modified by the fac-
        tor <lw> specified in lliinneewwiiddtthh. The default linewidth is 0.25
        points.  (1 "PostScript" point = 1/72 inch = 0.353 mm)

        rroouunnddeedd sets line caps and line joins to be rounded; bbuutttt is
        the default, butt caps and mitered joins.

        The default size for the output is 640 x 480 pixels. The ssiizzee
        option changes this to whatever the user requests. By default
        the X and Y sizes are taken to be in pixels, but other units
        are possibly (currently cm or inch).  A size given in centime-
        ters or inches is translated into pixels assuming a resolution
        of 72 dpi (currently this can't be changed).  Screen coordi-
        nates always run from 0.0 to 1.0 along the full length of the
        plot edges as specified by the ssiizzee option.

        <font> is in the format "FontFace,FontSize", i.e. the face and
        the size comma-separated in a single string. FontFace is a
        usual font face name, such as 'Arial'. If you do not provide
        FontFace, the pngcairo terminal will use 'Sans'. FontSize is
        the font size, in points. If you do not provide it, the png-
        cairo terminal will use a size of 6 points.
           For example :
              set term pngcairo font "Arial,12"
              set term pngcairo font "Arial" # to change the font face
        only
              set term pngcairo font ",12" # to change the font size
        only
              set term pngcairo font "" # to reset the font name and
        size

        The fonts are retrieved from the usual fonts subsystems. Under
        Windows, those fonts are to be found and configured in the
        entry "Fonts" of the control panel. Under UNIX, they are han-
        dled by "fontconfig".

        Pango, the library used to layout the text, is based on utf-8.
        Thus, the pngcairo terminal has to convert from your encoding
        to utf-8. The default input encoding is based on your 'locale'.
        If you want to use another encoding, make sure gnuplot knows
        which one you are using. See eennccooddiinngg for more details.










   GNUPLOT 4.1                                                      291


        Pango may give unexpected results with fonts that do not
        respect the unicode mapping. With the Symbol font, for example,
        the pngcairo terminal will use the map provided by
        http://www.unicode.org/ to translate character codes to uni-
        code.  Note that "the Symbol font" is to be understood as the
        Adobe Symbol font, distributed with Acrobat Reader as
        "SY______.PFB".  Alternatively, the OpenSymbol font, distrib-
        uted with OpenOffice.org as "opens___.ttf", offers the same
        characters. Microsoft has distributed a Symbol font ("sym-
        bol.ttf"), but it has a different character set with several
        missing or moved mathematic characters. If you experience prob-
        lems with your default setup (if the demo enhancedtext.dem is
        not displayed properly for example), you probably have to
        install one of the Adobe or OpenOffice Symbol fonts, and remove
        the Microsoft one.  Other non-conform fonts, such as
        "wingdings" have been observed working.

        The rendering of the plot cannot be altered yet. To obtain the
        best output possible, the rendering involves two mechanisms :
        antialiasing and oversampling.  Antialiasing allows to display
        non-horizontal and non-vertical lines smoother.  Oversampling
        combined with antialiasing provides subpixel accuracy, so that
        gnuplot can draw a line from non-integer coordinates. This
        avoids wobbling effects on diagonal lines ('plot x' for exam-
        ple).




        8877..5555..  PPoossttssccrriipptt


        Several options may be set in the ppoossttssccrriipptt driver.

        Syntax:
              set terminal postscript {default}
              set terminal postscript {landscape | portrait | eps}
                                      {enhanced | noenhanced}
                                      {defaultplex | simplex | duplex}
                                      {fontfile [add | delete] "<file-
        name>"
                                       | nofontfiles} {{no}adobeglyph-
        names}
                                      {level1 | leveldefault}
                                      {color | colour | monochrome}
                                      {solid | dashed}
                                      {dashlength | dl <DL>}
                                      {linewidth | lw <LW>}
                                      {rounded | butt}
                                      {clip | noclip}
                                      {palfuncparam <samples>{,<maxde-
        viation>}}
                                      {size <XX>{unit},<YY>{unit}}










   GNUPLOT 4.1                                                      292


                                      {blacktext | colortext | colour-
        text}
                                      {{font} "fontname{,fontsize}"
        {<fontsize>}}
        If you see the error message
              "Can't find PostScript prologue file ... "
        Please see and follow the instructions in ppoossttssccrriipptt pprroolloogguuee.


        llaannddssccaappee and ppoorrttrraaiitt choose the plot orientation.  eeppss mode
        generates EPS (Encapsulated PostScript) output, which is just
        regular PostScript with some additional lines that allow the
        file to be imported into a variety of other applications.  (The
        added lines are PostScript comment lines, so the file may still
        be printed by itself.)  To get EPS output, use the eeppss mode and
        make only one plot per file.  In eeppss mode the whole plot,
        including the fonts, is reduced to half of the default size.

        eennhhaanncceedd enables enhanced text mode features (subscripts,
        superscripts and mixed fonts). See eennhhaanncceedd for more informa-
        tion.  bbllaacckktteexxtt forces all text to be written in black even in
        color mode;

        Duplexing in PostScript is the ability of the printer to print
        on both sides of the same sheet of paper.  With ddeeffaauullttpplleexx,
        the default setting of the printer is used; with ssiimmpplleexx only
        one side is printed; dduupplleexx prints on both sides (ignored if
        your printer can't do it).

        ""<<ffoonnttnnaammee>>"" is the name of a valid PostScript font; and <<ffoonntt--
        ssiizzee>> is the size of the font in PostScript points.  In addi-
        tion to the standard postscript fonts, an oblique version of
        the Symbol font, useful for mathematics, is defined. It is
        called "Symbol-Oblique".

        ddeeffaauulltt sets all options to their defaults: llaannddssccaappee, mmoonnoo--
        cchhrroommee, ddaasshheedd, ddll 11..00, llww 11..00, ddeeffaauullttpplleexx, nnooeennhhaanncceedd, "Hel-
        vetica" and 14pt.  Default size of a PostScript plot is 10
        inches wide and 7 inches high.  The option ccoolloorr enables color,
        while mmoonnoocchhrroommee prefers black and white drawing elements. Fur-
        ther, mmoonnoocchhrroommee uses gray ppaalleettttee but it does not change color
        of objects specified with an explicit ccoolloorrssppeecc.  ssoolliidd draws
        all plots with solid lines, overriding any dashed patterns.
        ddaasshhlleennggtthh or ddll scales the length of the dashed-line segments
        by <DL>, which is a floating-point number greater than zero.
        lliinneewwiiddtthh or llww scales all linewidths by <LW>.

        By default the generated PostScript code uses language features
        that were introduced in PostScript Level 2, notably filters and
        pattern-fill of irregular objects such as filledcurves.  Post-
        Script Level 2 features are conditionally protected so that
        PostScript Level 1 interpreters do not issue errors but,
        rather, display a message or a PostScript Level 1










   GNUPLOT 4.1                                                      293


        approximation.  The lleevveell11 option substitutes PostScript Level
        1 approximations of these features and uses no PostScript Level
        2 code.  This may be required by some old printers and old ver-
        sions of Adobe Illustrator.  The flag lleevveell11 can be toggled
        later by editing a single line in the PostScript output file to
        force PostScript Level 1 interpretation.  In the case of files
        containing level 2 code, the above features will not appear or
        will be replaced by a note when this flag is set or when the
        interpreting program does not indicate that it understands
        level 2 PostScript or higher.

        rroouunnddeedd sets line caps and line joins to be rounded; bbuutttt is
        the default, butt caps and mitered joins.

        cclliipp tells PostScript to clip all output to the bounding box;
        nnoocclliipp is the default.

        ppaallffuunnccppaarraamm controls how sseett ppaalleettttee ffuunnccttiioonnss are encoded as
        gradients in the output. Analytic color component functions
        (set via sseett ppaalleettttee ffuunnccttiioonnss) are encoded as linear interpo-
        lated gradients in the postscript output:  The color component
        functions are sampled at <samples> points and all points are
        removed from this gradient which can be removed without chang-
        ing the resulting colors by more than <maxdeviation>. For
        almost every useful palette you may savely leave the defaults
        of <samples>=2000 and <maxdeviation>=0.003 untouched.

        The default size for postscript output is 10 inches x 7 inches.
        The default for eps output is 5 x 3.5 inches.  The ssiizzee option
        changes this to whatever the user requests. By default the X
        and Y sizes are taken to be in inches, but other units are pos-
        sibly (currently only cm). The BoundingBox of the plot is cor-
        rectly adjusted to contain the resized image.  Screen coordi-
        nates always run from 0.0 to 1.0 along the full length of the
        plot edges as specified by the ssiizzee option.  NB: tthhiiss iiss aa
        cchhaannggee ffrroomm tthhee pprreevviioouussllyy rreeccoommmmeennddeedd mmeetthhoodd ooff uussiinngg tthhee sseett
        ssiizzee ccoommmmaanndd pprriioorr ttoo sseettttiinngg tthhee tteerrmmiinnaall ttyyppee.  The old
        method left the BoundingBox unchanged and screen coordinates
        did not correspond to the actual limits of the plot.

        Fonts listed by ffoonnttffiillee or ffoonnttffiillee aadddd encapsulate the font
        definitions of the listed font from a postscript Type 1 or
        TrueType font file directly into the gnuplot output postscript
        file.  Thus, the enclosed font can be used in labels, titles,
        etc.  See the section ppoossttssccrriipptt ffoonnttffiillee for more details.
        With ffoonnttffiillee ddeelleettee, a fontfile is deleted from the list of
        embedded files.  nnooffoonnttffiilleess cleans the list of embedded fonts.

        Examples:
              set terminal postscript default       # old postscript
              set terminal postscript enhanced      # old enhpost
              set terminal postscript landscape 22  # old psbig
              set terminal postscript eps 14        # old epsf1










   GNUPLOT 4.1                                                      294


              set terminal postscript eps 22        # old epsf2
              set size 0.7,1.4; set term post portrait color "Times-
        Roman" 14
              set term post "VAGRoundedBT_Regular" 14 fontfile
        "bvrr8a.pfa"

        Linewidths and pointsizes may be changed with sseett ssttyyllee lliinnee.

        The ppoossttssccrriipptt driver supports about 70 distinct pointtypes,
        selectable through the ppooiinnttttyyppee option on pplloott and sseett ssttyyllee
        lliinnee.

        Several possibly useful files about ggnnuupplloott's PostScript are
        included in the /docs/psdoc subdirectory of the ggnnuupplloott distri-
        bution and at the distribution sites.  These are "ps_sym-
        bols.gpi" (a ggnnuupplloott command file that, when executed, creates
        the file "ps_symbols.ps" which shows all the symbols available
        through the ppoossttssccrriipptt terminal), "ps_guide.ps" (a PostScript
        file that contains a summary of the enhanced syntax and a page
        showing what the octal codes produce with text and symbol
        fonts), "ps_file.doc" (a text file that contains a discussion
        of the organization of a PostScript file written by ggnnuupplloott),
        and "ps_fontfile_doc.tex" (a LaTeX file which contains a short
        documentation concerning the encapsulation of LaTeX fonts with
        a glyph table of the math fonts).

        A PostScript file is editable, so once ggnnuupplloott has created one,
        you are free to modify it to your heart's desire.  See the
        eeddiittiinngg ppoossttssccrriipptt section for some hints.




             8877..5555..11..  EEddiittiinngg ppoossttssccrriipptt


             The PostScript language is a very complex language---far
             too complex to describe in any detail in this document.
             Nevertheless there are some things in a PostScript file
             written by ggnnuupplloott that can be changed without risk of
             introducing fatal errors into the file.

             For example, the PostScript statement "/Color true def"
             (written into the file in response to the command sseett tteerr--
             mmiinnaall ppoossttssccrriipptt ccoolloorr), may be altered in an obvious way
             to generate a black-and-white version of a plot.  Simi-
             larly line colors, text colors, line weights and symbol
             sizes can also be altered in straight-forward ways.  Text
             (titles and labels) can be edited to correct misspellings
             or to change fonts.  Anything can be repositioned, and of
             course anything can be added or deleted, but modifications
             such as these may require deeper knowledge of the Post-
             Script language.










   GNUPLOT 4.1                                                      295


             The organization of a PostScript file written by ggnnuupplloott
             is discussed in the text file "ps_file.doc" in the docs/ps
             subdirectory of the gnuplot source distribution.



             8877..5555..22..  PPoossttssccrriipptt ffoonnttffiillee


             The ffoonnttffiillee or ffoonnttffiillee aadddd option takes one file name as
             argument and encapsulates this file into the postscript
             output in order to make this font available for text ele-
             ments (labels, tic marks, titles, etc.).  The ffoonnttffiillee
             ddeelleettee option also takes one file name as argument. It
             deletes this file name from the list of encapsulated
             files.

             The postscript terminal understands some font file for-
             mats: Type 1 fonts in ASCII file format (extension
             ".pfa"), Type 1 fonts in binary file format (extension
             ".pfb"), and TrueType fonts (extension ".ttf"). Pfa files
             are understood directly, pfb and ttf files are converted
             on the fly if appropriate conversion tools are installed
             (see below). You have to specify the full filename includ-
             ing the extension. Each ffoonnttffiillee option takes exact one
             font file name. This option can be used multiple times in
             order to include more than one font file.

             The font file is searched in the working directory and in
             all directories listed in the fontpath which is determined
             by sseett ffoonnttppaatthh.  In addition, the fontpath can be set
             using the environment variable GNUPLOT_FONTPATH. If this
             is not set a system dependent default search list is used.
             See sseett ffoonnttppaatthh for more details.

             For using the encapsulated font file you have to specify
             the font name (which normally is not the same as the file
             name). When embedding a font file by using the ffoonnttffiillee
             option in interactive mode, the font name is printed on
             the screen. E.g.
                Font file 'p052004l.pfb' contains the font 'URWPalla-
             dioL-Bold'. Location:
                /usr/lib/X11/fonts/URW/p052004l.pfb

             When using pfa or pfb fonts, you can also find it out by
             looking into the font file. There is a line similar to
             "/FontName /URWPalladioL-Bold def".  The middle string
             without the slash is the fontname, here "URWPalladioL-
             Bold".  For TrueType fonts, this is not so easy since the
             font name is stored in a binary format. In addition, they
             often have spaces in the font names which is not supported
             by Type 1 fonts (in which a TrueType is converted on the
             fly). The font names are changed in order to eliminate the










   GNUPLOT 4.1                                                      296


             spaces in the fontnames. The easiest way to find out which
             font name is generated for use with gnuplot, start gnuplot
             in interactive mode and type in "set terminal postscript
             fontfile '<filename.ttf>'".

             For converting font files (either ttf or pfb) to pfa for-
             mat, the conversion tool has to read the font from a file
             and write it to standard output. If the output cannot be
             written to standard output, on-the-fly conversion is not
             possible.

             For pfb files "pfbtops" is a tool which can do this. If
             this program is installed on your system the on the fly
             conversion should work.  Just try to encapsulate a pfb
             file. If the compiled in program call does not work cor-
             rectly you can specify how this program is called by
             defining the environment variable GNUPLOT_PFBTOPFA e.g. to
             "pfbtops %s". The %%ss will be replaced by the font file
             name and thus has to exist in the string.

             If you don't want to do the conversion on the fly but get
             a pfa file of the font you can use the tool "pfb2pfa"
             which is written in simple c and should compile with any c
             compiler.  It is available from many ftp servers, e.g.
                       ftp://ftp.dante.de/tex-archive/fonts/utili-
             ties/ps2mf/
             In fact, "pfbtopfa" and "pfb2ps" do the same job.
             "pfbtopfa" puts the resulting pfa code into a file,
             whereas "pfbtops" writes it to standard output.

             TrueType fonts are converted into Type 1 pfa format, e.g.
             by using the tool "ttf2pt1" which is available from
                       http://ttf2pt1.sourceforge.net/
             If the builtin conversion does not work, the conversion
             command can be changed by the environment variable GNU-
             PLOT_TTFTOPFA. For usage with ttf2pt1 it may be set to
             "ttf2pt1 -a -e -W 0 %s - ". Here again, %%ss stands for the
             file name.

             For special purposes you also can use a pipe (if available
             for your operating system). Therefore you start the file
             name definition with the character "<" and append a pro-
             gram call. This program has to write pfa data to standard
             output. Thus, a pfa file may be accessed by sseett ffoonnttffiillee
             ""<< ccaatt ggaarraammoonndd..ppffaa"".

             For example, including Type 1 font files can be used for
             including the postscript output in LaTeX documents. The
             "european computer modern" font (which is a variant of the
             "computer modern" font) is available in pfb format from
             any CTAN server, e.g.
                       ftp://ftp.dante.de/tex-archive/fonts/ps-
             type1/cm-super/










   GNUPLOT 4.1                                                      297


             For example, the file "sfrm1000.pfb" contains the normal
             upright fonts with serifs in the design size 10pt (font
             name "SFRM1000").  The computer modern fonts, which are
             still necessary for mathematics, are available from
                       ftp://ftp.dante.de/tex-archive/fonts/cm/ps-
             type1/bluesky
             With these you can use any character available in TeX.
             However, the computer modern fonts have a strange encod-
             ing. (This is why you should not use cmr10.pfb for text,
             but sfrm1000.pfb instead.)  The usage of TeX fonts is
             shown in one of the demos.  The file "ps_fontfile_doc.tex"
             in the /docs/psdoc subdirectory of the ggnnuupplloott source dis-
             tribution contains a table with glyphs of the TeX math-
             fonts.

             If the font "CMEX10" is embedded (file "cmex10.pfb") gnu-
             plot defines the additional font "CMEX10-Baseline". It is
             shifted vertically in order to fit better to the other
             glyphs (CMEX10 has its baseline at the top of the sym-
             bols).



             8877..5555..33..  PPoossttssccrriipptt pprroolloogguuee


             Each PostScript output file includes a %%Prolog section
             and possibly some additional user-defined sections con-
             taining, for example, character encodings. These sections
             are copied from a set of PostScript prologue files which
             are either compiled in the gnuplot executable or stored
             elsewhere on your computer. This behaviour and the default
             directory where these files live are controlled at the
             time gnuplot is built. However, you can control this
             either by defining an environment variable GNUPLOT_PS_DIR
             or by using the gnuplot command sseett llooaaddppaatthh. See sseett
             llooaaddppaatthh.



             8877..5555..44..  PPoossttssccrriipptt aaddoobbeeggllyypphhnnaammeess


             This setting is only relevant to PostScript output with
             UTF-8 encoding.  It controls the names used to describe
             characters with Unicode entry points higher than 0x00FF.
             That is, all characters outside of the Latin1 set.  In
             general unicode characters do not have a unique name; they
             have only a unicode identification code.  However, Adobe
             have a recommended scheme for assigning names to certain
             ranges of characters (extended Latin, Greek, etc).  Some
             fonts use this scheme, others do not.  By default, gnuplot
             will use the Adobe glyph names.  E.g. the lower case Greek










   GNUPLOT 4.1                                                      298


             letter alpha will be called /alpha.  If you specific nnooaadd--
             oobbeeggllyypphhnnaammeess then instead gnuplot will use /uni03B1 to
             describe this character.  If you get this setting wrong,
             the character may not be found even if it is present in
             the font.  It is probably always correct to use the
             default for Adobe fonts, but for other fonts you may have
             to try both settings.  See also ffoonnttffiillee.





        8877..5566..  PPssllaatteexx aanndd ppsstteexx


        The ppssllaatteexx driver generates output for further processing by
        LaTeX, while the ppsstteexx driver generates output for further pro-
        cessing by TeX. ppssllaatteexx uses \specials understandable by dvips
        and xdvi. Figures generated by ppsstteexx can be included in any
        plain-based format (including LaTeX).

        Syntax:
              set terminal [pslatex | pstex] {default}
              set terminal [pslatex | pstex]
                                      {rotate | norotate}
                                      {oldstyle | newstyle}
                                      {auxfile | noauxfile}
                                      {level1 | leveldefault}
                                      {color | colour | monochrome}
                                      {solid | dashed}
                                      {dashlength | dl <DL>}
                                      {linewidth | lw <LW>}
                                      {rounded | butt}
                                      {clip | noclip}
                                      {palfuncparam <samples>{,<maxde-
        viation>}}
                                      {size <XX>{unit},<YY>{unit}}
                                      {<font_size>}

        If you see the error message
              "Can't find PostScript prologue file ... "
        Please see and follow the instructions in ppoossttssccrriipptt pprroolloogguuee.

        The option ccoolloorr enables color, while mmoonnoocchhrroommee prefers black
        and white drawing elements. Further, mmoonnoocchhrroommee uses gray
        ppaalleettttee but it does not change color of objects specified with
        an explicit ccoolloorrssppeecc.  ssoolliidd draws all plots with solid lines,
        overriding any dashed patterns.  ddaasshhlleennggtthh or ddll scales the
        length of the dashed-line segments by <DL>, which is a float-
        ing-point number greater than zero.  lliinneewwiiddtthh or llww scales all
        linewidths by <LW>.

        By default the generated PostScript code uses language features










   GNUPLOT 4.1                                                      299


        that were introduced in PostScript Level 2, notably filters and
        pattern-fill of irregular objects such as filledcurves.  Post-
        Script Level 2 features are conditionally protected so that
        PostScript Level 1 interpreters do not issue errors but,
        rather, display a message or a PostScript Level 1 approxima-
        tion.  The lleevveell11 option substitutes PostScript Level 1 approx-
        imations of these features and uses no PostScript Level 2 code.
        This may be required by some old printers and old versions of
        Adobe Illustrator.  The flag lleevveell11 can be toggled later by
        editing a single line in the PostScript output file to force
        PostScript Level 1 interpretation.  In the case of files con-
        taining level 2 code, the above features will not appear or
        will be replaced by a note when this flag is set or when the
        interpreting program does not indicate that it understands
        level 2 PostScript or higher.

        rroouunnddeedd sets line caps and line joins to be rounded; bbuutttt is
        the default, butt caps and mitered joins.

        cclliipp tells PostScript to clip all output to the bounding box;
        nnoocclliipp is the default.

        ppaallffuunnccppaarraamm controls how sseett ppaalleettttee ffuunnccttiioonnss are encoded as
        gradients in the output. Analytic color component functions
        (set via sseett ppaalleettttee ffuunnccttiioonnss) are encoded as linear interpo-
        lated gradients in the postscript output:  The color component
        functions are sampled at <samples> points and all points are
        removed from this gradient which can be removed without chang-
        ing the resulting colors by more than <maxdeviation>. For
        almost every useful palette you may savely leave the defaults
        of <samples>=2000 and <maxdeviation>=0.003 untouched.

        The default size for postscript output is 10 inches x 7 inches.
        The default for eps output is 5 x 3.5 inches.  The ssiizzee option
        changes this to whatever the user requests. By default the X
        and Y sizes are taken to be in inches, but other units are pos-
        sibly (currently only cm). The BoundingBox of the plot is cor-
        rectly adjusted to contain the resized image.  Screen coordi-
        nates always run from 0.0 to 1.0 along the full length of the
        plot edges as specified by the ssiizzee option.  NB: tthhiiss iiss aa
        cchhaannggee ffrroomm tthhee pprreevviioouussllyy rreeccoommmmeennddeedd mmeetthhoodd ooff uussiinngg tthhee sseett
        ssiizzee ccoommmmaanndd pprriioorr ttoo sseettttiinngg tthhee tteerrmmiinnaall ttyyppee.  The old
        method left the BoundingBox unchanged and screen coordinates
        did not correspond to the actual limits of the plot.

        if rroottaattee is specified, the y-axis label is rotated.
        <font_size> is the size (in pts) of the desired font.

        If aauuxxffiillee is specified, it directs the driver to put the Post-
        Script commands into an auxiliary file instead of directly into
        the LaTeX file.  This is useful if your pictures are large
        enough that dvips cannot handle them.  The name of the auxil-
        iary PostScript file is derived from the name of the TeX file










   GNUPLOT 4.1                                                      300


        given on the sseett oouuttppuutt command; it is determined by replacing
        the trailing ..tteexx (actually just the final extent in the file
        name) with ..ppss in the output file name, or, if the TeX file has
        no extension, ..ppss is appended.  The ..ppss is included into the
        ..tteexx file by a \special{psfile=...} command.  Remember to close
        the oouuttppuutt ffiillee before next plot unless in mmuullttiipplloott mode.

        Gnuplot versions prior to version 4.2 generated plots of the
        size 5 x 3 inches using the ps(la)tex terminal while the cur-
        rent version generates 5 x 3.5 inches to be consistent with the
        postscript eps terminal.  In addition, the character width is
        now estimated to be 60% of the font size while the old epslatex
        terminal used 50%. To reach the old format specify the option
        oollddssttyyllee.

        The pslatex driver offers a special way of controlling text
        positioning: (a) If any text string begins with '{', you also
        need to include a '}' at the end of the text, and the whole
        text will be centered both horizontally and vertically by
        LaTeX.  (b) If the text string begins with '[', you need to
        continue it with: a position specification (up to two out of
        t,b,l,r), ']{', the text itself, and finally, '}'. The text
        itself may be anything LaTeX can typeset as an LR-box.
        \rule{}{}'s may help for best positioning.

        The options not described here are identical to the PPoossttssccrriipptt
        tteerrmmiinnaall.  Look there if you want to know what they do.

        Examples:
              set term pslatex monochrome dashed rotate       # set to
        defaults
        To write the PostScript commands into the file "foo.ps":
              set term pslatex auxfile
              set output "foo.tex"; plot ...; set output
        About label positioning: Use gnuplot defaults (mostly sensible,
        but sometimes not really best):
               set title '\LaTeX\ -- $ \gamma $'
        Force centering both horizontally and vertically:
               set label '{\LaTeX\ -- $ \gamma $}' at 0,0
        Specify own positioning (top here):
               set xlabel '[t]{\LaTeX\ -- $ \gamma $}'
        The other label -- account for long ticlabels:
               set ylabel '[r]{\LaTeX\ -- $ \gamma $\rule{7mm}{0pt}}'

        Linewidths and pointsizes may be changed with sseett ssttyyllee lliinnee.



        8877..5577..  PPssttrriicckkss


        The ppssttrriicckkss driver is intended for use with the "pstricks.sty"
        macro package for LaTeX.  It is an alternative to the eeeeppiicc and










   GNUPLOT 4.1                                                      301


        llaatteexx drivers.  You need "pstricks.sty", and, of course, a
        printer that understands PostScript, or a converter such as
        Ghostscript.

        PSTricks is available via anonymous ftp from the /pub directory
        at Princeton.edu.  This driver definitely does not come close
        to using the full capability of the PSTricks package.

        Syntax:
              set terminal pstricks {hacktext | nohacktext} {unit |
        nounit}

        The first option invokes an ugly hack that gives nicer numbers;
        the second has to do with plot scaling.  The defaults are hhaacckk--
        tteexxtt and nnoouunniitt.



        8877..5588..  QQmmss


        The qqmmss terminal driver supports the QMS/QUIC Laser printer,
        the Talaris 1200 and others.  It has no options.



        8877..5599..  RReeggiiss


        The rreeggiiss terminal device generates output in the REGIS graph-
        ics language.  It has the option of using 4 (the default) or 16
        colors.

        Syntax:
              set terminal regis {4 | 16}



        8877..6600..  RRggiipp


        The rrggiipp and uunniipplleexx terminal drivers support RGIP metafiles.
        They can combine several graphs on a single page, but only one
        page is allowed in a given output file.

        Syntax:
              set terminal rgip | uniplex {portrait | landscape}
                                          {[<horiz>,<vert>]} {<font-
        size>}

        permissible values for the font size are in the range 1--8,
        with the default being 1.  The default layout is landscape.
        Graphs are placed on the page in a hhoorriizzxvveerrtt grid, which










   GNUPLOT 4.1                                                      302


        defaults to [1,1].

        Example:
              set terminal uniplex portrait [2,3]

        puts six graphs on a page in three rows of two in portrait ori-
        entation.



        8877..6611..  SSuunn


        The ssuunn terminal driver supports the SunView window system.  It
        has no options.



        8877..6622..  SSvvgg


        This terminal produces files in the W3C Scalable Vector Graph-
        ics format.

        Syntax:
              set terminal svg {size <x>,<y> {|fixed|dynamic}}
                               {{no}enhanced}
                               {fname "<font>"} {fsize <fontsize>}
                               {font "<fontname>{,<fontsize>}"}
                               {fontfile <filename>}
                               {rounded|butt} {solid|dashed} {linewidth
        <lw>}

        where <x> and <y> are the size of the SVG plot to generate,
        ddyynnaammiicc allows a svg-viewer to resize plot, whereas the default
        setting, ffiixxeedd, will request an absolute size.

        lliinneewwiiddtthh <<ww>> increases the width of all lines used in the fig-
        ure by a factor of <w>.

        <font> is the name of the default font to use (default Arial)
        and <fontsize> is the font size (in points, default 12). SVG
        viewing programs may substitute other fonts when the file is
        displayed.

        The svg terminal supports an enhanced text mode, which allows
        font and other formatting commands to be embedded in labels and
        other text strings. The enhanced text mode syntax is shared
        with other gnuplot terminal types. See eennhhaanncceedd for more
        details.

        SVG allows you to embed fonts directly into an SVG document, or
        to provide a hypertext link to the desired font. The ffoonnttffiillee










   GNUPLOT 4.1                                                      303


        option specifies a local file which is copied into the <defs>
        section of the resulting SVG output file.  This file may either
        itself contain a font, or may contain the records necessary to
        create a hypertext reference to the desired font. Gnuplot will
        look for the requested file using the directory list in the
        GNUPLOT_FONTPATH environmental variable.  NB: You must embed an
        svg font, not a TrueType or PostScript font.



        8877..6633..  SSvvggaa


        The ssvvggaa terminal driver supports PCs with SVGA graphics.  It
        can only be used if it is compiled with DJGPP.  Its only option
        is the font.

        Syntax:
              set terminal svga {"<fontname>"}



        8877..6644..  TTeekk4400


        This family of terminal drivers supports a variety of VT-like
        terminals.  tteekk4400xxxx supports Tektronix 4010 and others as well
        as most TEK emulators.  vvtttteekk supports VT-like tek40xx terminal
        emulators.  The following are present only if selected when
        gnuplot is built: kkcc--tteekk4400xxxx supports MS-DOS Kermit Tek4010
        terminal emulators in color; kkmm--tteekk4400xxxx supports them in mono-
        chrome. sseellaannaarr supports Selanar graphics.  bbiittggrraapphh supports
        BBN Bitgraph terminals.  None have any options.



        8877..6655..  TTeekk441100xx


        The tteekk441100xx terminal driver supports the 410x and 420x family
        of Tektronix terminals.  It has no options.



        8877..6666..  TTeexxddrraaww


        The tteexxddrraaww terminal driver supports the LaTeX texdraw environ-
        ment.  It is intended for use with "texdraw.sty" and "tex-
        draw.tex" in the texdraw package.

        Points, among other things, are drawn using the LaTeX commands
        "\Diamond" and "\Box".  These commands no longer belong to the










   GNUPLOT 4.1                                                      304


        LaTeX2e core; they are included in the latexsym package, which
        is part of the base distribution and thus part of any LaTeX
        implementation.  Please do not forget to use this package.

        It has no options.



        8877..6677..  TTggiiff


        Tgif is an X11-based drawing tool---it has nothing to do with
        GIF.

        The ttggiiff driver supports different pointsizes (with sseett ppooiinntt--
        ssiizzee), different label fonts and font sizes (e.g. sseett llaabbeell
        ""HHaalllloo"" aatt xx,,yy ffoonntt ""HHeellvveettiiccaa,,3344"") and multiple graphs on the
        page.  The proportions of the axes are not changed.

        Syntax:
              set terminal tgif {portrait | landscape | default}
        {<[x,y]>}
                                {monochrome | color}
                                {{linewidth | lw} <LW>}
                                {solid | dashed}
                                {font "<fontname>"} {<fontsize>}

        where <[x,y]> specifies the number of graphs in the x and y
        directions on the page, ccoolloorr enables color, lliinneewwiiddtthh scales
        all linewidths by <LW>, "<fontname>" is the name of a valid
        PostScript font, and <fontsize> specifies the size of the Post-
        Script font.  ddeeffaauullttss sets all options to their defaults: ppoorr--
        ttrraaiitt, [[11,,11]], ccoolloorr, lliinnwwiiddtthh 11..00, ddaasshheedd, ""HHeellvveettiiccaa"", and 1188.

        The ssoolliidd option is usually prefered if lines are colored, as
        they often are in the editor.  Hardcopy will be black-and-
        white, so ddaasshheedd should be chosen for that.

        Multiplot is implemented in two different ways.

        The first multiplot implementation is the standard gnuplot mul-
        tiplot feature:

              set terminal tgif
              set output "file.obj"
              set multiplot
              set origin x01,y01
              set size  xs,ys
              plot ...
                   ...
              set origin x02,y02
              plot ...
              unset multiplot










   GNUPLOT 4.1                                                      305


        See sseett mmuullttiipplloott for further information.

        The second version is the [x,y] option for the driver itself.
        The advantage of this implementation is that everything is
        scaled and placed automatically without the need for setting
        origins and sizes; the graphs keep their natural x/y propor-
        tions of 3/2 (or whatever is fixed by sseett ssiizzee).

        If both multiplot methods are selected, the standard method is
        chosen and a warning message is given.

        Examples of single plots (or standard multiplot):
              set terminal tgif                  # defaults
              set terminal tgif "Times-Roman" 24
              set terminal tgif landscape
              set terminal tgif landscape solid

        Examples using the built-in multiplot mechanism:
              set terminal tgif portrait [2,4]  # portrait; 2 plots in
        the x-
                                                # and 4 in the y-direc-
        tion
              set terminal tgif [1,2]           # portrait; 1 plot in
        the x-
                                                # and 2 in the y-direc-
        tion
              set terminal tgif landscape [3,3] # landscape; 3 plots in
        both
                                                # directions



        8877..6688..  TTiikkzz


        This driver creates output for use with the TikZ package of
        graphics macros in TeX.  It is currently implemented via an
        external lua script, and sseett tteerrmm ttiikkzz is a short form of the
        command sseett tteerrmm lluuaa ttiikkzz.  See tteerrmm lluuaa for more information.
        Use the command sseett tteerrmm ttiikkzz hheellpp to print terminal options.



        8877..6699..  TTkkccaannvvaass


        This terminal driver generates Tk canvas widget commands based
        on Tcl/Tk (default) or Perl.  To use it, rebuild ggnnuupplloott (after
        uncommenting or inserting the appropriate line in "term.h"),
        then

         gnuplot> set term tkcanvas {perltk} {interactive}
         gnuplot> set output 'plot.file'










   GNUPLOT 4.1                                                      306


        After invoking "wish", execute the following sequence of Tcl/Tk
        commands:

         % source plot.file
         % canvas .c
         % pack .c
         % gnuplot .c

        Or, for Perl/Tk use a program like this:

         use Tk;
         my $top = MainWindow->new;
         my $c = $top->Canvas->pack;
         my $gnuplot = do "plot.pl";
         $gnuplot->($c);
         MainLoop;

        The code generated by ggnnuupplloott creates a procedure called "gnu-
        plot" that takes the name of a canvas as its argument.  When
        the procedure is called, it clears the canvas, finds the size
        of the canvas and draws the plot in it, scaled to fit.

        For 2-dimensional plotting (pplloott) two additional procedures are
        defined: "gnuplot_plotarea" will return a list containing the
        borders of the plotting area "xleft, xright, ytop, ybot" in
        canvas screen coordinates, while the ranges of the two axes
        "x1min, x1max, y1min, y1max, x2min, x2max, y2min, y2max" in
        plot coordinates can be obtained calling "gnuplot_axisranges".
        If the "interactive" option is specified, mouse clicking on a
        line segment will print the coordinates of its midpoint to std-
        out. Advanced actions can happen instead if the user supplies a
        procedure named "user_gnuplot_coordinates", which takes the
        following arguments: "win id x1s y1s x2s y2s x1e y1e x2e y2e
        x1m y1m x2m y2m", the name of the canvas and the id of the line
        segment followed by the coordinates of its start and end point
        in the two possible axis ranges; the coordinates of the mid-
        point are only filled for logarithmic axes.

        The current version of ttkkccaannvvaass supports neither mmuullttiipplloott nor
        rreepplloott.



        8877..7700..  TTppiicc


        The ttppiicc terminal driver supports the LaTeX picture environment
        with tpic \specials.  It is an alternative to the llaatteexx and
        eeeeppiicc terminal drivers.  Options are the point size, line
        width, and dot-dash interval.

        Syntax:
              set terminal tpic <pointsize> <linewidth> <interval>










   GNUPLOT 4.1                                                      307


        where ppooiinnttssiizzee and lliinneewwiiddtthh are integers in milli-inches and
        iinntteerrvvaall is a float in inches.  If a non-positive value is
        specified, the default is chosen: pointsize = 40, linewidth =
        6, interval = 0.1.

        All drivers for LaTeX offer a special way of controlling text
        positioning: If any text string begins with '{', you also need
        to include a '}' at the end of the text, and the whole text
        will be centered both horizontally and vertically by LaTeX. ---
        If the text string begins with '[', you need to continue it
        with: a position specification (up to two out of t,b,l,r),
        ']{', the text itself, and finally, '}'. The text itself may be
        anything LaTeX can typeset as an LR-box. \rule{}{}'s may help
        for best positioning.

        Examples: About label positioning: Use gnuplot defaults (mostly
        sensible, but sometimes not really best):
               set title '\LaTeX\ -- $ \gamma $'
        Force centering both horizontally and vertically:
               set label '{\LaTeX\ -- $ \gamma $}' at 0,0
        Specify own positioning (top here):
               set xlabel '[t]{\LaTeX\ -- $ \gamma $}'
        The other label -- account for long ticlabels:
               set ylabel '[r]{\LaTeX\ -- $ \gamma $\rule{7mm}{0pt}}'



        8877..7711..  UUnniixxppcc


        The uunniixxppcc terminal driver supports AT&T 3b1 and AT&T 7300 Unix
        PC.  It has no options.



        8877..7722..  UUnniixxpplloott


        The uunniixxpplloott terminal driver generates output in the Unix
        "plot" graphics language.  It has no options.

        This terminal cannot be compiled if the GNU version of plot is
        to be used; in that case, use the ggnnuuggrraapphh terminal instead.



        8877..7733..  VVggaaggll


        The vvggaaggll driver is a fast linux console driver with full mouse
        and pm3d support.  It looks at the environment variable
        SVGALIB_DEFAULT_MODE for the default mode; if not set, it uses
        a 256 color mode with the highest available resolution.










   GNUPLOT 4.1                                                      308


        Syntax:
           set terminal vgagl \
                        background [red] [[green] [blue]] \
                        [uniform | interpolate] \
                        [mode]

        The color mode can also be given with the mode option. Both
        Symbolic names as G1024x768x256 and integers are allowed. The
        bbaacckkggrroouunndd option takes either one or three integers in the
        range [0, 255]. If only one integers is supplied, it is taken
        as gray value for the background.  If three integers are
        present, the background gets the corresponding color.  The
        (mutually exclusive) options iinntteerrppoollaattee and uunniiffoorrmm control if
        color interpolation is done while drawing triangles (on by
        default).

        To get high resolution modes, you will probably have to modify
        the configuration file of libvga, usually /etc/vga/libvga.conf.
        Using the VESA fb is a good choice, but this needs to be com-
        piled in the kernel.

        The vgagl driver uses the first *available* vga mode from the
        following list:
         - the driver which was supplied when setting vgagl, e.g. `set
        term vgagl
           G1024x768x256` would first check, if the G1024x768x256 mode
        is available.
         - the environment variable SVGALIB_DEFAULT_MODE
         - G1024x768x256
         - G800x600x256
         - G640x480x256
         - G320x200x256
         - G1280x1024x256
         - G1152x864x256
         - G1360x768x256
         - G1600x1200x256




        8877..7744..  VVWWSS


        The VVWWSS terminal driver supports the VAX Windowing System.  It
        has no options.  It will sense the display type (monochrome,
        gray scale, or color.)  All line styles are plotted as solid
        lines.
















   GNUPLOT 4.1                                                      309


        8877..7755..  VVxx338844


        The vvxx338844 terminal driver supports the Vectrix 384 and Tandy
        color printers.  It has no options.



        8877..7766..  WWiinnddoowwss


        Three options may be set in the wwiinnddoowwss terminal driver.

        Syntax:
              set terminal windows {color | monochrome}
                                   {enhanced | noenhanced}
                                   {{font} "fontname{,fontsize}"
        {<fontsize>}}
                                   {title "Plot Window Title"}
                                   {size <width>,<height>}
                                   {position <x>,<y>}
                                   {close}

        where ccoolloorr and mmoonnoocchhrroommee select colored or mono output,
        eennhhaanncceedd enables enhanced text mode features (subscripts,
        superscripts and mixed fonts). See eennhhaanncceedd for more informa-
        tion.  ""<<ffoonnttnnaammee>>"" is the name of a valid Windows font, and
        <<ffoonnttssiizzee>> is the size of the font in points.  ssiizzee defines the
        width and height of the window in pixel and ppoossiittiioonn the origin
        of the window i.e. the position of the top left corner on the
        screen (again in pixel). Both these options override the
        default settings from the WGNUPLOT.INI file (see below).

        Other options may be set with the graph-menu or the initializa-
        tion file.

        The Windows version normally terminates immediately as soon as
        the end of any files given as command line arguments is reached
        (i.e. in non-interactive mode), unless you specify -- as the
        last command line option.  It will also not show the text-win-
        dow at all, in this mode, only the plot.  By giving the
        optional argument --ppeerrssiisstt (same as for gnuplot under x11; for-
        mer Windows-only options //nnooeenndd or --nnooeenndd are still accepted as
        well), will not close gnuplot. Contrary to gnuplot on other
        operating systems, gnuplot's interactive command line is acces-
        sible after the -persist option.

        The plot window remains open even when the gnuplot driver is
        changed to a different device. The plot window can be close
        with sseett tteerrmm wwiinnddoowwss cclloossee













   GNUPLOT 4.1                                                      310


             8877..7766..11..  GGrraapphh--mmeennuu


             The ggnnuupplloott ggrraapphh window has the following options on a
             pop-up menu accessed by pressing the right mouse button or
             selecting OOppttiioonnss from the system menu:

             BBrriinngg ttoo TToopp when checked brings the graph window to the
             top after every plot.

             CCoolloorr when checked enables color linestyles.  When
             unchecked it forces monochrome linestyles.

             CCooppyy ttoo CClliippbbooaarrdd copies a bitmap and an enhanced Metafile
             picture.

             SSaavvee aass EEMMFF...... allows the user to save the current graph
             window as enhanced metafile

             BBaacckkggrroouunndd...... sets the window background color.

             CChhoooossee FFoonntt...... selects the font used in the graphics win-
             dow.

             LLiinnee SSttyylleess...... allows customization of the line colors and
             styles.

             PPrriinntt...... prints the graphics windows using a Windows
             printer driver and allows selection of the printer and
             scaling of the output.  The output produced by PPrriinntt is
             not as good as that from ggnnuupplloott's own printer drivers.

             UUppddaattee wwggnnuupplloott..iinnii saves the current window locations,
             window sizes, text window font, text window font size,
             graph window font, graph window font size, background
             color and linestyles to the initialization file WWGGNNUU--
             PPLLOOTT..IINNII.



             8877..7766..22..  PPrriinnttiinngg


             In order of preference, graphs may be be printed in the
             following ways.

             11.. Use the ggnnuupplloott command sseett tteerrmmiinnaall to select a
             printer and sseett oouuttppuutt to redirect output to a file.

             22.. Select the PPrriinntt...... command from the ggnnuupplloott ggrraapphh win-
             dow.  An extra command ssccrreeeenndduummpp does this from the text
             window.











   GNUPLOT 4.1                                                      311


             33.. If sseett oouuttppuutt ""PPRRNN"" is used, output will go to a tempo-
             rary file.  When you exit from ggnnuupplloott or when you change
             the output with another sseett oouuttppuutt command, a dialog box
             will appear for you to select a printer port.  If you
             choose OK, the output will be printed on the selected
             port, passing unmodified through the print manager.  It is
             possible to accidentally (or deliberately) send printer
             output meant for one printer to an incompatible printer.



             8877..7766..33..  TTeexxtt--mmeennuu


             The ggnnuupplloott tteexxtt window has the following options on a
             pop-up menu accessed by pressing the right mouse button or
             selecting OOppttiioonnss from the system menu:

             CCooppyy ttoo CClliippbbooaarrdd copies marked text to the clipboard.

             PPaassttee copies text from the clipboard as if typed by the
             user.

             CChhoooossee FFoonntt...... selects the font used in the text window.

             SSyysstteemm CCoolloorrss when selected makes the text window honor
             the System Colors set using the Control Panel.  When unse-
             lected, text is black or blue on a white background.

             UUppddaattee wwggnnuupplloott..iinnii saves the current text window loca-
             tion, text window size, text window font and text window
             font size to the initialisation file WWGGNNUUPPLLOOTT..IINNII.

             MMEENNUU BBAARR

             If the menu file WWGGNNUUPPLLOOTT..MMNNUU is found in the same direc-
             tory as WGNUPLOT.EXE, then the menu specified in WWGGNNUU--
             PPLLOOTT..MMNNUU will be loaded.  Menu commands:

             [Menu] starts a new menu with the name on the following
             line.

             [EndMenu] ends the current menu.

             [--] inserts a horizontal menu separator.

             [|] inserts a vertical menu separator.

             [Button] puts the next macro on a push button instead of a
             menu.

             Macros take two lines with the macro name (menu entry) on
             the first line and the macro on the second line.  Leading










   GNUPLOT 4.1                                                      312


             spaces are ignored.  Macro commands:

             [INPUT] --- Input string with prompt terminated by [EOS]
             or {ENTER}

             [EOS] --- End Of String terminator.  Generates no output.

             [OPEN] --- Get name of file to open from list box, with
             title of list box terminated by [EOS], followed by default
             filename terminated by [EOS] or {ENTER}.

             [SAVE] --- Get name of file to save.  Similar to [OPEN]

             Macro character substitutions:

             {ENTER} --- Carriage Return '\r'

             {TAB} --- Tab '\011'

             {ESC} --- Escape '\033'

             {^A} --- '\001'

             ...

             {^_} --- '\031'

             Macros are limited to 256 characters after expansion.



             8877..7766..44..  WWggnnuupplloott..iinnii


             Windows ggnnuupplloott will read some of its options from the
             [[WWGGNNUUPPLLOOTT]] section of WWGGNNUUPPLLOOTT..IINNII in user's %APPDATA%
             directory.  A sample WWGGNNUUPPLLOOTT..IINNII file:

                   [WGNUPLOT]
                   TextOrigin=0 0
                   TextSize=640 150
                   TextFont=Terminal,9
                   GraphOrigin=0 150
                   GraphSize=640 330
                   GraphFont=Arial,10
                   GraphColor=1
                   GraphToTop=1
                   GraphBackground=255 255 255
                   Border=0 0 0 0 0
                   Axis=192 192 192 2 2
                   Line1=0 0 255 0 0
                   Line2=0 255 0 0 1
                   Line3=255 0 0 0 2










   GNUPLOT 4.1                                                      313


                   Line4=255 0 255 0 3
                   Line5=0 0 128 0 4

             The GGrraapphhFFoonntt entry specifies the font name and size in
             points.  The five numbers given in the BBoorrddeerr, AAxxiiss and
             LLiinnee entries are the RReedd intensity (0--255), GGrreeeenn inten-
             sity, BBlluuee intensity, CCoolloorr LLiinneessttyyllee and MMoonnoo LLiinneessttyyllee.
             LLiinneessttyylleess are 0=SOLID, 1=DASH, 2=DOT, 3=DASHDOT, 4=DASH-
             DOTDOT.  In the sample WWGGNNUUPPLLOOTT..IINNII file above, Line 2 is
             a green solid line in color mode, or a dashed line in
             monochrome mode.  The default line width is 1 pixel.  If
             LLiinneessttyyllee is negative, it specifies the width of a SOLID
             line in pixels.  Line1 and any linestyle used with the
             ppooiinnttss style must be SOLID with unit width.



        8877..7777..  WWxxtt


        The wwxxtt terminal device generates output in a separate window.
        The window is created by the wxWidgets library, where the 'wxt'
        comes from. The actual drawing is done via cairo, a 2D graphics
        library, and pango, a library for laying out and rendering
        text.

        Syntax:
                set term wxt {<n>}
                             {size <width>,<height>}
                             {{no}enhanced}
                             {font <font>}
                             {title "title"}
                             {dashed|solid} {dashlength <dl>}
                             {{no}persist}
                             {{no}raise}
                             {{no}ctrl}
                             {close}

        Multiple plot windows are supported: sseett tteerrmmiinnaall wwxxtt <<nn>>
        directs the output to plot window number n.

        The default window title is based on the window number. This
        title can also be specified with the keyword "title".

        Plot windows remain open even when the ggnnuupplloott driver is
        changed to a different device.  A plot window can be closed by
        pressing the letter 'q' while that window has input focus, by
        choosing cclloossee from a window manager menu, or with sseett tteerrmm wwxxtt
        <<nn>> cclloossee.

        The size of the plot area is given in pixels, it defaults to
        640x384.  In addition to that, the actual size of the window
        also includes the space reserved for the toolbar and the status










   GNUPLOT 4.1                                                      314


        bar.  When you resize a window, the plot is immediately scaled
        to fit in the new size of the window. Unlike other interactive
        terminals, the wwxxtt terminal scales the whole plot, including
        fonts and linewidths, and keeps its global aspect ratio con-
        stant, leaving an empty space painted in gray.  If you type
        rreepplloott, click the rreepplloott icon in the terminal toolbar or type a
        new pplloott command, the new plot will completely fit in the win-
        dow and the font size and the linewidths will be reset to their
        defaults.

        The active plot window (the one selected by sseett tteerrmm wwxxtt <<nn>>)
        is interactive. Its behaviour is shared with other terminal
        types. See mmoouussee for details. It also has some extra icons,
        which are supposed to be self-explanatory.

        This terminal supports an enhanced text mode, which allows font
        and other formatting commands (subscripts, superscripts, etc.)
        to be embedded in labels and other text strings. The enhanced
        text mode syntax is shared with other gnuplot terminal types.
        See eennhhaanncceedd for more details.

        <font> is in the format "FontFace,FontSize", i.e. the face and
        the size comma-separated in a single string. FontFace is a
        usual font face name, such as 'Arial'. If you do not provide
        FontFace, the wxt terminal will use 'Sans'. FontSize is the
        font size, in points. If you do not provide it, the wxt termi-
        nal will use a size of 10 points.
           For example :
              set term wxt font "Arial,12"
              set term wxt font "Arial" # to change the font face only
              set term wxt font ",12" # to change the font size only
              set term wxt font "" # to reset the font name and size

        The fonts are retrieved from the usual fonts subsystems. Under
        Windows, those fonts are to be found and configured in the
        entry "Fonts" of the control panel. Under UNIX, they are han-
        dled by "fontconfig".

        Pango, the library used to layout the text, is based on utf-8.
        Thus, the wxt terminal has to convert from your encoding to
        utf-8. The default input encoding is based on your 'locale'. If
        you want to use another encoding, make sure gnuplot knows which
        one you are using. See eennccooddiinngg for more details.

        Pango may give unexpected results with fonts that do not
        respect the unicode mapping. With the Symbol font, for example,
        the wxt terminal will use the map provided by http://www.uni-
        code.org/ to translate character codes to unicode.  Pango will
        do its best to find a font containing this character, looking
        for your Symbol font, or other fonts with a broad unicode cov-
        erage, like the DejaVu fonts. Note that "the Symbol font" is to
        be understood as the Adobe Symbol font, distributed with Acro-
        bat Reader as "SY______.PFB".  Alternatively, the OpenSymbol










   GNUPLOT 4.1                                                      315


        font, distributed with OpenOffice.org as "opens___.ttf", offers
        the same characters. Microsoft has distributed a Symbol font
        ("symbol.ttf"), but it has a different character set with sev-
        eral missing or moved mathematic characters. If you experience
        problems with your default setup (if the demo enhancedtext.dem
        is not displayed properly for example), you probably have to
        install one of the Adobe or OpenOffice Symbol fonts, and remove
        the Microsoft one.  Other non-conform fonts, such as
        "wingdings" have been observed working.

        The rendering of the plot can be altered with a dialog avail-
        able from the toolbar. To obtain the best output possible, the
        rendering involves three mechanisms : antialiasing, oversam-
        pling and hinting.  Antialiasing allows to display non-horizon-
        tal and non-vertical lines smoother.  Oversampling combined
        with antialiasing provides subpixel accuracy, so that gnuplot
        can draw a line from non-integer coordinates. This avoids wob-
        bling effects on diagonal lines ('plot x' for example).  Hint-
        ing avoids the blur on horizontal and vertical lines caused by
        oversampling. The terminal will snap these lines to integer
        coordinates so that a one-pixel-wide line will actually be
        drawn on one and only one pixel.

        By default, the window is raised to the top of your desktop
        when a plot is drawn. This can be controlled with the keyword
        "raise".  The keyword "persist" will prevent gnuplot from exit-
        ing before you explicitely close all the plot windows.
        Finally, by default the key <space> raises the gnuplot console
        window, and 'q' closes the plot window. The keyword "ctrl"
        allows you to replace those bindings by <ctrl>+<space> and
        <ctrl>+'q', respectively.  These three keywords (raise, persist
        and ctrl) can also be set and remembered between sessions
        through the configuration dialog.



        8877..7788..  XX1111


        ggnnuupplloott provides the xx1111 terminal type for use with X servers.
        This terminal type is set automatically at startup if the DDIISS--
        PPLLAAYY environment variable is set, if the TTEERRMM environment vari-
        able is set to xxtteerrmm, or if the --ddiissppllaayy command line option is
        used.

        Syntax:
           set terminal x11 {<n> | window "<string>"}
                            {title "<string>"}
                            {{no}enhanced} {font <fontspec>}
                            {linewidth LW} {solid|dashed}
                            {{no}persist} {{no}raise} {{no}ctrlq}
                            {close}
                            {size XX,YY} {position XX,YY}










   GNUPLOT 4.1                                                      316


           set terminal x11 {reset}

        Multiple plot windows are supported: sseett tteerrmmiinnaall xx1111 <<nn>>
        directs the output to plot window number n.  If n is not 0, the
        terminal number will be appended to the window title (unless a
        title has been supplied manually) and the icon will be labeled
        GGnnuupplloott <<nn>>.  The active window may be distinguished by a
        change in cursor (from default to crosshair).

        The xx1111 terminal can connect to X windows previously created by
        an outside application via the option wwiinnddooww followed by a
        string containing the X ID for the window in hexadecimal for-
        mat.  Gnuplot uses that external X window as a container since
        X does not allow for multiple clients selecting the ButtonPress
        event.  In this way, gnuplot's mouse features work within the
        contained plot window.

           set term x11 window "220001e"

        The x11 terminal supports enhanced text mode (see eennhhaanncceedd),
        subject to the available fonts. In order for font size commands
        embedded in text to have any effect, the default x11 font must
        be scalable. Thus the first example below will work as
        expected, but the second will not.

           set term x11 enhanced font "arial,15"
           set title '{/=20 Big} Medium {/=5 Small}'

           set term x11 enhanced font "terminal-14"
           set title '{/=20 Big} Medium {/=5 Small}'

        Plot windows remain open even when the ggnnuupplloott driver is
        changed to a different device.  A plot window can be closed by
        pressing the letter q while that window has input focus, or by
        choosing cclloossee from a window manager menu.  All plot windows
        can be closed by specifying rreesseett, which actually terminates
        the subprocess which maintains the windows (unless --ppeerrssiisstt was
        specified).  The cclloossee command can be used to close individual
        plot windows by number.  However, after a rreesseett, those plot
        windows left due to persist cannot be closed with the command
        cclloossee.  A cclloossee without a number closes the current active plot
        window.

        The gnuplot outboard driver, gnuplot_x11, is searched in a
        default place chosen when the program is compiled.  You can
        override that by defining the environment variable GNU-
        PLOT_DRIVER_DIR to point to a different location.

        Plot windows will automatically be closed at the end of the
        session unless the --ppeerrssiisstt option was given.

        The options ppeerrssiisstt and rraaiissee are unset by default, which means
        that the defaults (persist == no and raise == yes) or the










   GNUPLOT 4.1                                                      317


        command line options -persist / -raise or the Xresources are
        taken.  If [no]persist or [no]raise are specified, they will
        override command line options and Xresources.  Setting one of
        these options takes place immediately, so the behaviour of an
        already running driver can be modified.  If the window does not
        get raised, see discussion in rraaiissee.

        The option ttiittllee ""<<ttiittllee nnaammee>>"" will supply the title name of
        the window for the current plot window or plot window <n> if a
        number is given.  Where (or if) this title is shown depends on
        your X window manager.

        The size option can be used to set the size of the plot window.
        The size option will only apply to newly created windows.

        The position option can be used to set the position of the plot
        window.  The position option will only apply to newly created
        windows.

        The size or aspect ratio of a plot may be changed by resizing
        the ggnnuupplloott window.

        Linewidths and pointsizes may be changed from within ggnnuupplloott
        with sseett lliinneessttyyllee.

        For terminal type xx1111, ggnnuupplloott accepts (when initialized) the
        standard X Toolkit options and resources such as geometry,
        font, and name from the command line arguments or a configura-
        tion file.  See the X(1) man page (or its equivalent) for a
        description of such options.

        A number of other ggnnuupplloott options are available for the xx1111
        terminal.  These may be specified either as command-line
        options when ggnnuupplloott is invoked or as resources in the configu-
        ration file ".Xdefaults".  They are set upon initialization and
        cannot be altered during a ggnnuupplloott session.  (except ppeerrssiisstt
        and rraaiissee)




             8877..7788..11..  XX1111__ffoonnttss


             Upon initial startup, the default font is taken from the
             X11 resources as set in the system or user .Xdefaults file
             or on the command line.

             Example:
                   gnuplot*font: lucidasans-bold-12
             A new default font may be specified to the x11 driver from
             inside gnuplot using
                  `set term x11 font "<fontspec>"`










   GNUPLOT 4.1                                                      318


             The driver first queries the X-server for a font of the
             exact name given.  If this query fails, then it tries to
             interpret <fontspec> as "<font>,<size>,<slant>,<weight>"
             and to construct a full X11 font name of the form
                   -*-<font>-<weight>-<s>-*-*-<size>-*-*-*-*-*-<encod-
             ing>

              <font> is the base name of the font (e.g. Times or Sym-
             bol)
              <size> is the point size (defaults to 12 if not speci-
             fied)
              <s> is `i` if <slant>=="italic" `o` if <slant>=="oblique"
             `r` otherwise
              <weight> is `medium` or `bold` if explicitly requested,
             otherwise `*`
              <encoding> is set based on the current character set (see
             `set encoding`).
             So sseett tteerrmm xx1111 ffoonntt ""aarriiaall,,1155,,iittaalliicc"" will be translated
             to -*-arial-*-i-*-*-15-*-*-*-*-*-iso8859-1 (assuming
             default encoding).  The <size>, <slant>, and <weight>
             specifications are all optional.  If you do not specify
             <slant> or <weight> then you will get whatever font vari-
             ant the font server offers first.  You may set a default
             enconding via the corresponding X11 resource. E.g.
                   gnuplot*encoding: iso8859-15
             The driver also recognizes some common PostScript font
             names and replaces them with possible X11 or TrueType
             equivalents.  This same sequence is used to process font
             requests from sseett llaabbeell.

             If your gnuplot was built with configuration option
             --enable-x11-mbfonts, you can specify multi-byte fonts by
             using the prefix "mbfont:" on the font name. An additional
             font may be given, separated by a semicolon.  Since multi-
             byte font encodings are interpreted according to the
             locale setting, you must make sure that the environmental
             variable LC_CTYPE is set to some appropriate locale value
             such as ja_JP.eucJP, ko_KR.EUC, or zh_CN.EUC.

             Example:
                   set term x11 font 'mbfont:kana14;k14'
                         # 'kana14' and 'k14' are Japanese X11 font
             aliases, and ';'
                         # is the separator of font names.
                   set term x11 font 'mbfont:fixed,16,r,medium'
                         # <font>,<size>,<slant>,<weight> form is also
             usable.
                   set title '(mb strings)' font 'mbfont:*-fixed-
             medium-r-normal--14-*'

             The same syntax applies to the default font in Xresources
             settings, for example,
                   gnuplot*font: \










   GNUPLOT 4.1                                                      319


                       mbfont:-misc-fixed-medium-r-nor-
             mal--14-*-*-*-c-*-jisx0208.1983-0

             If gnuplot is built with --enable-x11-mbfonts, you can use
             two special PostScript font names 'Ryumin-Light-*' and
             'GothicBBB-Medium-*' (standard Japanese PS fonts) without
             the prefix "mbfont:".




             8877..7788..22..  CCoommmmaanndd--lliinnee__ooppttiioonnss


             In addition to the X Toolkit options, the following
             options may be specified on the command line when starting
             ggnnuupplloott or as resources in your ".Xdefaults" file (note
             that rraaiissee and ppeerrssiisstt can be overridden later by sseett tteerrmm
             xx1111 [[nnoo]]rraaiissee [[nnoo]]ppeerrssiisstt)):



   +-----------------------------------------------------------------------------+
   |  `-mono`      forces monochrome rendering on color displays.                |
   |  `-gray`      requests grayscale rendering on grayscale or color displays.  |
   |               (Grayscale displays receive monochrome rendering by default.) |
   |  `-clear`     requests that the window be cleared momentarily before a      |
   |               new plot is displayed.                                        |
   |  `-tvtwm`     requests that geometry specifications for position of the     |
   |               window be made relative to the currently displayed portion    |
   |               of the virtual root.                                          |
   |  `-raise`     raises plot window after each plot                            |
   | `-noraise`    does not raise plot window after each plot                    |
   |`-novevents`   does not process mouse and key events                         |
   |  `-ctrlq`     closes window on ctrl-q rather than q                         |
   | `-persist`    plot windows survive after main gnuplot program exits         |
   +-----------------------------------------------------------------------------+


   The options are shown above in their command-line syntax.  When
   entered as resources in ".Xdefaults", they require a different syn-
   tax.

   Example:
         gnuplot*gray:  on
         gnuplot*ctrlq: on

   ggnnuupplloott also provides a command line option (--ppooiinnttssiizzee <<vv>>) and a
   resource, ggnnuupplloott**ppooiinnttssiizzee:: <<vv>>, to control the size of points
   plotted with the ppooiinnttss plotting style.  The value vv is a real num-
   ber (greater than 0 and less than or equal to ten) used as a scaling
   factor for point sizes.  For example, --ppooiinnttssiizzee 22 uses points twice
   the default size, and --ppooiinnttssiizzee 00..55 uses points half the normal










   GNUPLOT 4.1                                                      320


   size.

   The --nnooeevveennttss switch disables all mouse and key event processing
   (except for qq and <<ssppaaccee>> for closing the window). This is useful
   for programs which use the x11 driver independent of the gnuplot
   main program.

   The --ccttrrllqq switch changes the hot-key that closes a plot window from
   qq to <<ccttrrll>>qq. This is useful is you are using the keystroke-capture
   feature ppaauussee mmoouussee kkeeyyssttrrookkee, since it allows the character qq to be
   captured just as all other alphanumeric characters. The --ccttrrllqq
   switch similarly replaces the <space> hot-key with <ctrl><space> for
   the same reason.




             8877..7788..33..  MMoonnoocchhrroommee__ooppttiioonnss


             For monochrome displays, ggnnuupplloott does not honor foreground
             or background colors.  The default is black-on-white.  --rrvv
             or ggnnuupplloott**rreevveerrsseeVViiddeeoo:: oonn requests white-on-black.




             8877..7788..44..  CCoolloorr__rreessoouurrcceess


             The X11 terminal honors the following resources (shown
             here with their default values) or the greyscale
             resources.  The values may be color names as listed in the
             X11 rgb.txt file on your system, hexadecimal RGB color
             specifications (see X11 documentation), or a color name
             followed by a comma and an iinntteennssiittyy value from 0 to 1.
             For example, bblluuee,, 00..55 means a half intensity blue.


























   GNUPLOT 4.1                                                      321


                    +--------------------------------+
                    |    gnuplot*background: white   |
                    |    gnuplot*textColor: black    |
                    |    gnuplot*borderColor: black  |
                    |    gnuplot*axisColor: black    |
                    |    gnuplot*line1Color: red     |
                    |    gnuplot*line2Color: green   |
                    |    gnuplot*line3Color: blue    |
                    |    gnuplot*line4Color: magenta |
                    |    gnuplot*line5Color: cyan    |
                    |    gnuplot*line6Color: sienna  |
                    |    gnuplot*line7Color: orange  |
                    |    gnuplot*line8Color: coral   |
                    +--------------------------------+



   The command-line syntax for these is simple only for background,
   which maps directly to the usual X11 toolkit option "-bg".  All oth-
   ers can only be set on the command line by use of the generic "-xrm"
   resource override option

   Examples:

         gnuplot -background coral
   to change the background color.

         gnuplot -xrm 'gnuplot*line1Color:blue'
   to override the first linetype color.




             8877..7788..55..  GGrraayyssccaallee__rreessoouurrcceess


             When --ggrraayy is selected, ggnnuupplloott honors the following
             resources for grayscale or color displays (shown here with
             their default values).  Note that the default background
             is black.























   GNUPLOT 4.1                                                      322


                     +-------------------------------+
                     |    gnuplot*background: black  |
                     |    gnuplot*textGray: white    |
                     |    gnuplot*borderGray: gray50 |
                     |    gnuplot*axisGray: gray50   |
                     |    gnuplot*line1Gray: gray100 |
                     |    gnuplot*line2Gray: gray60  |
                     |    gnuplot*line3Gray: gray80  |
                     |    gnuplot*line4Gray: gray40  |
                     |    gnuplot*line5Gray: gray90  |
                     |    gnuplot*line6Gray: gray50  |
                     |    gnuplot*line7Gray: gray70  |
                     |    gnuplot*line8Gray: gray30  |
                     +-------------------------------+






             8877..7788..66..  LLiinnee__rreessoouurrcceess


             ggnnuupplloott honors the following resources for setting the
             width (in pixels) of plot lines (shown here with their
             default values.)  0 or 1 means a minimal width line of 1
             pixel width.  A value of 2 or 3 may improve the appearance
             of some plots.



                       +---------------------------+
                       |    gnuplot*borderWidth: 2 |
                       |    gnuplot*axisWidth: 0   |
                       |    gnuplot*line1Width: 0  |
                       |    gnuplot*line2Width: 0  |
                       |    gnuplot*line3Width: 0  |
                       |    gnuplot*line4Width: 0  |
                       |    gnuplot*line5Width: 0  |
                       |    gnuplot*line6Width: 0  |
                       |    gnuplot*line7Width: 0  |
                       |    gnuplot*line8Width: 0  |
                       +---------------------------+



   ggnnuupplloott honors the following resources for setting the dash style
   used for plotting lines.  0 means a solid line.  A two-digit number
   jjkk (jj and kk are >= 1 and <= 9) means a dashed line with a repeated
   pattern of jj pixels on followed by kk pixels off.  For example, '16'
   is a dotted line with one pixel on followed by six pixels off.  More
   elaborate on/off patterns can be specified with a four-digit value.
   For example, '4441' is four on, four off, four on, one off.  The










   GNUPLOT 4.1                                                      323


   default values shown below are for monochrome displays or monochrome
   rendering on color or grayscale displays.  Color displays default to
   dashed:off



                     +------------------------------+
                     |    gnuplot*dashed: off       |
                     |    gnuplot*borderDashes: 0   |
                     |    gnuplot*axisDashes: 16    |
                     |    gnuplot*line1Dashes: 0    |
                     |    gnuplot*line2Dashes: 42   |
                     |    gnuplot*line3Dashes: 13   |
                     |    gnuplot*line4Dashes: 44   |
                     |    gnuplot*line5Dashes: 15   |
                     |    gnuplot*line6Dashes: 4441 |
                     |    gnuplot*line7Dashes: 42   |
                     |    gnuplot*line8Dashes: 13   |
                     +------------------------------+






             8877..7788..77..  XX1111 ppmm33dd__rreessoouurrcceess


             Choosing the appropriate visual class and number of colors
             is a crucial point in X11 applications and a bit awkward,
             since X11 supports six visual types in different depths.

             By default ggnnuupplloott uses the default visual of the screen.
             The number of colors which can be allocated depends on the
             visual class chosen. On a visual class with a depth >
             12bit, gnuplot starts with a maximal number of 0x200 col-
             ors.  On a visual class with a depth > 8bit (but <= 12
             bit) the maximal number of colors is 0x100, on <= 8bit
             displays the maximum number of colors is 240 (16 are left
             for line colors).

             Gnuplot first starts to allocate the maximal number of
             colors as stated above.  If this fails, the number of col-
             ors is reduced by the factor 2 until gnuplot gets all col-
             ors which are requested. If dividing mmaaxxccoolloorrss by 2
             repeatedly results in a number which is smaller than mmiinn--
             ccoolloorrss ggnnuupplloott tries to install a private colormap. In
             this case the window manager is responsible for swapping
             colormaps when the pointer is moved in and out the x11
             driver's window.

             The default for mmiinnccoolloorrss is maxcolors / (num_colormaps >
             1 ? 2 : 8), where num_colormaps is the number of colormaps










   GNUPLOT 4.1                                                      324


             which are currently used by gnuplot (usually 1, if only
             one x11 window is open).

             Some systems support multiple (different) visual classes
             together on one screen. On these systems it might be nec-
             essary to force gnuplot to use a specific visual class,
             e.g. the default visual might be 8bit PseudoColor but the
             screen would also support 24bit TrueColor which would be
             the preferred choice.

             The information about an Xserver's capabilities can be
             obtained with the program xxddppyyiinnffoo.  For the visual names
             below you can choose one of StaticGray, GrayScale, Static-
             Color, PseudoColor, TrueColor, DirectColor.  If an Xserver
             supports a requested visual type at different depths, ggnnuu--
             pplloott chooses the visual class with the highest depth
             (deepest).  If the requested visual class matches the
             default visual and multiple classes of this type are sup-
             ported, the default visual is preferred.

             Example: on an 8bit PseudoColor visual you can force a
             private color map by specifying ggnnuupplloott**mmaaxxccoolloorrss:: 224400 and
             ggnnuupplloott**mmiinnccoolloorrss:: 224400.




                +-----------------------------------------+
                |    gnuplot*maxcolors:  <integer number> |
                |    gnuplot*mincolors:  <integer number> |
                |    gnuplot*visual:     <visual name>    |
                +-----------------------------------------+






             8877..7788..88..  XX1111 ootthheerr__rreessoouurrcceess


             By default the contents of the current plot window are
             exported to the X11 clipboard in response to X events in
             the window. Setting the resource 'gnuplot*exportselection'
             to 'off' or 'false' will disable this.

             By default text rotation is done using a method that is
             fast, but can corrupt nearby colors depending on the back-
             ground.  If this is a problem, you can set the resource
             'gnuplot.fastrotate' to 'off'













   GNUPLOT 4.1                                                      325


                   +----------------------------------+
                   |    gnuplot*exportselection:  off |
                   |    gnuplot*fastrotate:  on       |
                   |    gnuplot*ctrlq:  off           |
                   +----------------------------------+





        8877..7799..  XXlliibb


        The xxlliibb terminal driver supports the X11 Windows System.  It
        generates gnuplot_x11 commands, but sends them to the output
        file specified by sseett oouuttppuutt ''<<ffiilleennaammee>>''. sseett tteerrmm xx1111 is
        equivalent to sseett oouuttppuutt ""||ggnnuupplloott__xx1111 --nnooeevveennttss"";; sseett tteerrmm
        xxlliibb.  xxlliibb takes the same set of options as xx1111.




        8888..  GGrraapphhiiccaall UUsseerr IInntteerrffaacceess


        Several graphical user interfaces have been written for ggnnuupplloott
        and one for win32 is included in this distribution.

        Bruce Ravel (ravel@phys.washington.edu) has written a gnuplot-
        mode for GNU emacs and XEmacs based on  the earlier gnuplot.el
        file by Gershon Elber.  While the gnuplot CVS repository has
        its own copy the most recent version of this package is avail-
        able from
                  http://feff.phys.washington.edu/~ravel/software/gnu-
        plot-mode/
        For Python, Tk/Tcl, and other front-ends, check the links on
                 http://gnuplot.sourceforge.net/links.html





        8899..  BBuuggss


        Bugs reported since the current release as well as older ones
        may be located via the official distribution site on Source-
        Forge.

        Please e-mail bug reports to the gnuplot-bugs mailing list.  Or
        upload the report to the gnuplot web site on SourceForge.
        Please give complete information on the version of gnuplot you
        are using and, if possible, a test script that demonstrates the










   GNUPLOT 4.1                                                      326


        bug.  See SSeeeekkiinngg--aassssiissttaannccee.

        The sections below list problems known to be present in gnuplot
        version 4.4 at the time of release.  Some of these are actually
        bugs in external support libraries and may have been fixed
        independent of any changes in gnuplot.




        9900..  GGnnuupplloott lliimmiittaattiioonnss


        Floating point exceptions (floating point number too
        large/small, divide by zero, etc.) may occasionally be gener-
        ated by user defined functions.  Some of the demos in particu-
        lar may cause numbers to exceed the floating point range.
        Whether the system ignores such exceptions (in which case ggnnuu--
        pplloott labels the corresponding point as undefined) or aborts
        ggnnuupplloott depends on the compiler/runtime environment.

        The gamma, bessel, and erf functions do not work for complex
        arguments.

        Only one color palette at a time is active for any given x11
        plot window.  This means that multiplots whose constituent
        plots use different palettes will not display correctly in x11.

        Coordinates specified as "time" wrap at 24 hours, and have a
        precision limited to 1 second.  This is in particular a limita-
        tion in using time format to handle geographic coordinates.

        Error bars are not handled properly in polar/spherical coordi-
        nate plot modes.

        The 'nohidden3d' option that is supposed to exempt individual
        plots from the global property 'set hidden3d' does not work for
        parametric curves.




        9911..  EExxtteerrnnaall lliibbrraarriieess


        External library GD (used by PNG/JPEG/GIF drivers): Versions of
        libgd through 2.0.33 contain various bugs in mapping the char-
        acters of Adobe's Symbol font.  Also it is possible to trigger
        a library segfault if an anti-aliased line crosses an upper
        corner of the canvas.

        External library PDFlib (used by PDF driver): Gnuplot can be
        linked against libpdf versions 4, 5, or 6. However, these










   GNUPLOT 4.1                                                      327


        versions differ in their handling of piped I/O.  Therefore gnu-
        plot scripts using piped output to PDF may work only for some
        versions of PDFlib.

        External library svgalib (used by linux and vgagl driver):
        Requires gnuplot to be suid root (bad!) and has many bugs that
        are specific to the video card or graphics driver used in X11.

        Internationalization (locale settings): Gnuplot uses the C run-
        time library routine setlocale() to control locale-specific
        formatting of input and output number, times, and date strings.
        The locales available, and the level of support for locale fea-
        tures such as "thousands' grouping separator", depend on the
        internationalization support provided by your individual
        machine.
















































   GNUPLOT 4.1                                                        i



                               TTaabbllee ooff CCoonntteennttss


        Gnuplot . . . . . . . . . . . . . . . . . . . . . . . . . .   1
        Copyright . . . . . . . . . . . . . . . . . . . . . . . . .   1
        Introduction  . . . . . . . . . . . . . . . . . . . . . . .   2
        Seeking-assistance  . . . . . . . . . . . . . . . . . . . .   4
        New features introduced in version 4.4  . . . . . . . . . .   5
        Internationalization  . . . . . . . . . . . . . . . . . . .   5
        Transparency  . . . . . . . . . . . . . . . . . . . . . . .   5
        Volatile Data . . . . . . . . . . . . . . . . . . . . . . .   5
        Canvas size . . . . . . . . . . . . . . . . . . . . . . . .   5
        New plot elements . . . . . . . . . . . . . . . . . . . . .   6
        New or revised terminal drivers . . . . . . . . . . . . . .   6
        New smoothing algorithms  . . . . . . . . . . . . . . . . .   7
        Backwards compatibility . . . . . . . . . . . . . . . . . .   7
        Batch/Interactive Operation . . . . . . . . . . . . . . . .   8
        Command-line-editing  . . . . . . . . . . . . . . . . . . .   9
        Comments  . . . . . . . . . . . . . . . . . . . . . . . . .   9
        Coordinates . . . . . . . . . . . . . . . . . . . . . . . .  10
        Datastrings . . . . . . . . . . . . . . . . . . . . . . . .  10
        Enhanced text mode  . . . . . . . . . . . . . . . . . . . .  11
        Environment . . . . . . . . . . . . . . . . . . . . . . . .  13
        Expressions . . . . . . . . . . . . . . . . . . . . . . . .  14
        Functions . . . . . . . . . . . . . . . . . . . . . . . . .  15
        Elliptic integrals  . . . . . . . . . . . . . . . . . . . .  17
        Random number generator . . . . . . . . . . . . . . . . . .  18
        Value . . . . . . . . . . . . . . . . . . . . . . . . . . .  18
        Operators . . . . . . . . . . . . . . . . . . . . . . . . .  19
        Unary . . . . . . . . . . . . . . . . . . . . . . . . . . .  19
        Binary  . . . . . . . . . . . . . . . . . . . . . . . . . .  20
        Ternary . . . . . . . . . . . . . . . . . . . . . . . . . .  21
        Gnuplot-defined variables . . . . . . . . . . . . . . . . .  22
        User-defined variables and functions  . . . . . . . . . . .  22
        Fonts . . . . . . . . . . . . . . . . . . . . . . . . . . .  23
        Cairo (pdfcairo, pngcairo, wxt terminals) . . . . . . . . .  24
        Gd (png, gif, jpeg terminals) . . . . . . . . . . . . . . .  24
        Postscript  (also encapsulated postscript *.eps)  . . . . .  25
        Glossary  . . . . . . . . . . . . . . . . . . . . . . . . .  25
        Linetype, colors, and styles  . . . . . . . . . . . . . . .  26
        Colorspec . . . . . . . . . . . . . . . . . . . . . . . . .  28
        Rgbcolor variable . . . . . . . . . . . . . . . . . . . . .  29
        Linecolor variable  . . . . . . . . . . . . . . . . . . . .  30
        Mouse input . . . . . . . . . . . . . . . . . . . . . . . .  30
        Bind  . . . . . . . . . . . . . . . . . . . . . . . . . . .  31
        Bind space  . . . . . . . . . . . . . . . . . . . . . . . .  32
        Mouse variables . . . . . . . . . . . . . . . . . . . . . .  33
        Plotting  . . . . . . . . . . . . . . . . . . . . . . . . .  33
        Start-up  . . . . . . . . . . . . . . . . . . . . . . . . .  34
        String constants and string variables . . . . . . . . . . .  35
        Substitution and Command line macros  . . . . . . . . . . .  36
        Substitution of system commands in backquotes . . . . . . .  36










   GNUPLOT 4.1                                                       ii


        Substitution of string variables as macros  . . . . . . . .  36
        String variables, macros, and command line substitution . .  37
        Syntax  . . . . . . . . . . . . . . . . . . . . . . . . . .  38
        Quote Marks . . . . . . . . . . . . . . . . . . . . . . . .  39
        Time/Date data  . . . . . . . . . . . . . . . . . . . . . .  40
        Plotting styles . . . . . . . . . . . . . . . . . . . . . .  41
        Boxerrorbars  . . . . . . . . . . . . . . . . . . . . . . .  42
        Boxes . . . . . . . . . . . . . . . . . . . . . . . . . . .  42
        Boxxyerrorbars  . . . . . . . . . . . . . . . . . . . . . .  43
        Candlesticks  . . . . . . . . . . . . . . . . . . . . . . .  44
        Circles . . . . . . . . . . . . . . . . . . . . . . . . . .  45
        Dots  . . . . . . . . . . . . . . . . . . . . . . . . . . .  45
        Filledcurves  . . . . . . . . . . . . . . . . . . . . . . .  46
        Financebars . . . . . . . . . . . . . . . . . . . . . . . .  47
        Fsteps  . . . . . . . . . . . . . . . . . . . . . . . . . .  47
        Histeps . . . . . . . . . . . . . . . . . . . . . . . . . .  48
        Histograms  . . . . . . . . . . . . . . . . . . . . . . . .  48
        Newhistogram  . . . . . . . . . . . . . . . . . . . . . . .  51
        Automated iteration over multiple columns . . . . . . . . .  52
        Image . . . . . . . . . . . . . . . . . . . . . . . . . . .  52
        Transparency  . . . . . . . . . . . . . . . . . . . . . . .  53
        Image failsafe  . . . . . . . . . . . . . . . . . . . . . .  53
        Impulses  . . . . . . . . . . . . . . . . . . . . . . . . .  53
        Labels  . . . . . . . . . . . . . . . . . . . . . . . . . .  54
        Lines . . . . . . . . . . . . . . . . . . . . . . . . . . .  55
        Linespoints . . . . . . . . . . . . . . . . . . . . . . . .  55
        Points  . . . . . . . . . . . . . . . . . . . . . . . . . .  55
        Steps . . . . . . . . . . . . . . . . . . . . . . . . . . .  56
        Rgbalpha  . . . . . . . . . . . . . . . . . . . . . . . . .  56
        Rgbimage  . . . . . . . . . . . . . . . . . . . . . . . . .  56
        Vectors . . . . . . . . . . . . . . . . . . . . . . . . . .  56
        Xerrorbars  . . . . . . . . . . . . . . . . . . . . . . . .  57
        Xyerrorbars . . . . . . . . . . . . . . . . . . . . . . . .  57
        Yerrorbars  . . . . . . . . . . . . . . . . . . . . . . . .  57
        Xerrorlines . . . . . . . . . . . . . . . . . . . . . . . .  58
        Xyerrorlines  . . . . . . . . . . . . . . . . . . . . . . .  58
        Yerrorlines . . . . . . . . . . . . . . . . . . . . . . . .  58
        3D (surface) plots  . . . . . . . . . . . . . . . . . . . .  59
        Commands  . . . . . . . . . . . . . . . . . . . . . . . . .  59
        Cd  . . . . . . . . . . . . . . . . . . . . . . . . . . . .  60
        Call  . . . . . . . . . . . . . . . . . . . . . . . . . . .  60
        Clear . . . . . . . . . . . . . . . . . . . . . . . . . . .  61
        Evaluate  . . . . . . . . . . . . . . . . . . . . . . . . .  61
        Exit  . . . . . . . . . . . . . . . . . . . . . . . . . . .  62
        Fit . . . . . . . . . . . . . . . . . . . . . . . . . . . .  62
        Adjustable parameters . . . . . . . . . . . . . . . . . . .  65
        Short introduction  . . . . . . . . . . . . . . . . . . . .  65
        Error estimates . . . . . . . . . . . . . . . . . . . . . .  67
        Statistical overview  . . . . . . . . . . . . . . . . . . .  67
        Practical guidelines  . . . . . . . . . . . . . . . . . . .  68
        Control . . . . . . . . . . . . . . . . . . . . . . . . . .  70
        Control variables . . . . . . . . . . . . . . . . . . . . .  70
        Environment variables . . . . . . . . . . . . . . . . . . .  71










   =1 .if 0 .tl 'GNUPLOT 4.1''%'


        Multi-branch  . . . . . . . . . . . . . . . . . . . . . . .  71
        Starting values . . . . . . . . . . . . . . . . . . . . . .  72
        Tips  . . . . . . . . . . . . . . . . . . . . . . . . . . .  72
        Help  . . . . . . . . . . . . . . . . . . . . . . . . . . .  74
        History . . . . . . . . . . . . . . . . . . . . . . . . . .  74
        If  . . . . . . . . . . . . . . . . . . . . . . . . . . . .  75
        Iteration . . . . . . . . . . . . . . . . . . . . . . . . .  76
        Load  . . . . . . . . . . . . . . . . . . . . . . . . . . .  76
        Lower . . . . . . . . . . . . . . . . . . . . . . . . . . .  77
        Pause . . . . . . . . . . . . . . . . . . . . . . . . . . .  77
        Plot  . . . . . . . . . . . . . . . . . . . . . . . . . . .  78
        Axes  . . . . . . . . . . . . . . . . . . . . . . . . . . .  79
        Data  . . . . . . . . . . . . . . . . . . . . . . . . . . .  79
        Binary  . . . . . . . . . . . . . . . . . . . . . . . . . .  82
        Binary general  . . . . . . . . . . . . . . . . . . . . . .  83
        Array . . . . . . . . . . . . . . . . . . . . . . . . . . .  84
        Record  . . . . . . . . . . . . . . . . . . . . . . . . . .  84
        Skip  . . . . . . . . . . . . . . . . . . . . . . . . . . .  85
        Format  . . . . . . . . . . . . . . . . . . . . . . . . . .  85
        Endian  . . . . . . . . . . . . . . . . . . . . . . . . . .  85
        Filetype  . . . . . . . . . . . . . . . . . . . . . . . . .  86
        Avs . . . . . . . . . . . . . . . . . . . . . . . . . . . .  86
        Edf . . . . . . . . . . . . . . . . . . . . . . . . . . . .  86
        Png . . . . . . . . . . . . . . . . . . . . . . . . . . . .  87
        Keywords  . . . . . . . . . . . . . . . . . . . . . . . . .  87
        Scan  . . . . . . . . . . . . . . . . . . . . . . . . . . .  87
        Transpose . . . . . . . . . . . . . . . . . . . . . . . . .  88
        Dx, dy, dz  . . . . . . . . . . . . . . . . . . . . . . . .  88
        Flipx, flipy, flipz . . . . . . . . . . . . . . . . . . . .  88
        Origin  . . . . . . . . . . . . . . . . . . . . . . . . . .  89
        Center  . . . . . . . . . . . . . . . . . . . . . . . . . .  89
        Rotate  . . . . . . . . . . . . . . . . . . . . . . . . . .  89
        Perpendicular . . . . . . . . . . . . . . . . . . . . . . .  90
        Binary examples . . . . . . . . . . . . . . . . . . . . . .  90
        Every . . . . . . . . . . . . . . . . . . . . . . . . . . .  91
        Example datafile  . . . . . . . . . . . . . . . . . . . . .  92
        Index . . . . . . . . . . . . . . . . . . . . . . . . . . .  92
        Smooth  . . . . . . . . . . . . . . . . . . . . . . . . . .  93
        Acsplines . . . . . . . . . . . . . . . . . . . . . . . . .  94
        Bezier  . . . . . . . . . . . . . . . . . . . . . . . . . .  95
        Csplines  . . . . . . . . . . . . . . . . . . . . . . . . .  95
        Sbezier . . . . . . . . . . . . . . . . . . . . . . . . . .  95
        Unique  . . . . . . . . . . . . . . . . . . . . . . . . . .  95
        Frequency . . . . . . . . . . . . . . . . . . . . . . . . .  96
        Cumulative  . . . . . . . . . . . . . . . . . . . . . . . .  96
        Kdensity  . . . . . . . . . . . . . . . . . . . . . . . . .  96
        Special-filenames . . . . . . . . . . . . . . . . . . . . .  96
        Thru  . . . . . . . . . . . . . . . . . . . . . . . . . . .  99
        Using . . . . . . . . . . . . . . . . . . . . . . . . . . .  99
        Using_examples  . . . . . . . . . . . . . . . . . . . . . . 100
        Pseudocolumns . . . . . . . . . . . . . . . . . . . . . . . 102
        Xticlabels  . . . . . . . . . . . . . . . . . . . . . . . . 102
        X2ticlabels . . . . . . . . . . . . . . . . . . . . . . . . 103










   GNUPLOT 4.1                                                       iv


        Yticlabels  . . . . . . . . . . . . . . . . . . . . . . . . 103
        Y2ticlabels . . . . . . . . . . . . . . . . . . . . . . . . 103
        Zticlabels  . . . . . . . . . . . . . . . . . . . . . . . . 104
        Errorbars . . . . . . . . . . . . . . . . . . . . . . . . . 104
        Errorlines  . . . . . . . . . . . . . . . . . . . . . . . . 105
        Parametric  . . . . . . . . . . . . . . . . . . . . . . . . 106
        Ranges  . . . . . . . . . . . . . . . . . . . . . . . . . . 106
        Iteration . . . . . . . . . . . . . . . . . . . . . . . . . 108
        Title . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
        With  . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
        Print . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
        Pwd . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
        Quit  . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
        Raise . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
        Refresh . . . . . . . . . . . . . . . . . . . . . . . . . . 114
        Replot  . . . . . . . . . . . . . . . . . . . . . . . . . . 115
        Reread  . . . . . . . . . . . . . . . . . . . . . . . . . . 115
        Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
        Save  . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
        Set-show  . . . . . . . . . . . . . . . . . . . . . . . . . 118
        Angles  . . . . . . . . . . . . . . . . . . . . . . . . . . 118
        Arrow . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
        Autoscale . . . . . . . . . . . . . . . . . . . . . . . . . 121
        Parametric mode . . . . . . . . . . . . . . . . . . . . . . 123
        Polar mode  . . . . . . . . . . . . . . . . . . . . . . . . 124
        Bars  . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
        Bind  . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
        Bmargin . . . . . . . . . . . . . . . . . . . . . . . . . . 125
        Border  . . . . . . . . . . . . . . . . . . . . . . . . . . 125
        Boxwidth  . . . . . . . . . . . . . . . . . . . . . . . . . 127
        Clabel  . . . . . . . . . . . . . . . . . . . . . . . . . . 128
        Clip  . . . . . . . . . . . . . . . . . . . . . . . . . . . 128
        Cntrparam . . . . . . . . . . . . . . . . . . . . . . . . . 129
        Color box . . . . . . . . . . . . . . . . . . . . . . . . . 131
        Colornames  . . . . . . . . . . . . . . . . . . . . . . . . 132
        Contour . . . . . . . . . . . . . . . . . . . . . . . . . . 133
        Data style  . . . . . . . . . . . . . . . . . . . . . . . . 134
        Datafile  . . . . . . . . . . . . . . . . . . . . . . . . . 134
        Set datafile fortran  . . . . . . . . . . . . . . . . . . . 134
        Set datafile nofpe_trap . . . . . . . . . . . . . . . . . . 134
        Set datafile missing  . . . . . . . . . . . . . . . . . . . 135
        Set datafile separator  . . . . . . . . . . . . . . . . . . 136
        Set datafile commentschars  . . . . . . . . . . . . . . . . 136
        Set datafile binary . . . . . . . . . . . . . . . . . . . . 137
        Decimalsign . . . . . . . . . . . . . . . . . . . . . . . . 137
        Dgrid3d . . . . . . . . . . . . . . . . . . . . . . . . . . 139
        Dummy . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
        Encoding  . . . . . . . . . . . . . . . . . . . . . . . . . 141
        Fit . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142
        Fontpath  . . . . . . . . . . . . . . . . . . . . . . . . . 143
        Format  . . . . . . . . . . . . . . . . . . . . . . . . . . 144
        Gprintf . . . . . . . . . . . . . . . . . . . . . . . . . . 144
        Format specifiers . . . . . . . . . . . . . . . . . . . . . 145










   GNUPLOT 4.1                                                        v


        Time/date specifiers  . . . . . . . . . . . . . . . . . . . 146
        Function style  . . . . . . . . . . . . . . . . . . . . . . 148
        Functions . . . . . . . . . . . . . . . . . . . . . . . . . 148
        Grid  . . . . . . . . . . . . . . . . . . . . . . . . . . . 148
        Hidden3d  . . . . . . . . . . . . . . . . . . . . . . . . . 149
        Historysize . . . . . . . . . . . . . . . . . . . . . . . . 152
        Isosamples  . . . . . . . . . . . . . . . . . . . . . . . . 152
        Key . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153
        Key placement . . . . . . . . . . . . . . . . . . . . . . . 156
        Key samples . . . . . . . . . . . . . . . . . . . . . . . . 157
        Label . . . . . . . . . . . . . . . . . . . . . . . . . . . 158
        Lmargin . . . . . . . . . . . . . . . . . . . . . . . . . . 161
        Loadpath  . . . . . . . . . . . . . . . . . . . . . . . . . 161
        Locale  . . . . . . . . . . . . . . . . . . . . . . . . . . 162
        Logscale  . . . . . . . . . . . . . . . . . . . . . . . . . 162
        Macros  . . . . . . . . . . . . . . . . . . . . . . . . . . 163
        Mapping . . . . . . . . . . . . . . . . . . . . . . . . . . 163
        Margin  . . . . . . . . . . . . . . . . . . . . . . . . . . 164
        Mouse . . . . . . . . . . . . . . . . . . . . . . . . . . . 164
        X11 mouse . . . . . . . . . . . . . . . . . . . . . . . . . 167
        Multiplot . . . . . . . . . . . . . . . . . . . . . . . . . 167
        Mx2tics . . . . . . . . . . . . . . . . . . . . . . . . . . 169
        Mxtics  . . . . . . . . . . . . . . . . . . . . . . . . . . 169
        My2tics . . . . . . . . . . . . . . . . . . . . . . . . . . 170
        Mytics  . . . . . . . . . . . . . . . . . . . . . . . . . . 170
        Mztics  . . . . . . . . . . . . . . . . . . . . . . . . . . 170
        Object  . . . . . . . . . . . . . . . . . . . . . . . . . . 171
        Rectangle . . . . . . . . . . . . . . . . . . . . . . . . . 171
        Ellipse . . . . . . . . . . . . . . . . . . . . . . . . . . 172
        Circle  . . . . . . . . . . . . . . . . . . . . . . . . . . 173
        Polygon . . . . . . . . . . . . . . . . . . . . . . . . . . 173
        Offsets . . . . . . . . . . . . . . . . . . . . . . . . . . 174
        Origin  . . . . . . . . . . . . . . . . . . . . . . . . . . 174
        Output  . . . . . . . . . . . . . . . . . . . . . . . . . . 175
        Parametric  . . . . . . . . . . . . . . . . . . . . . . . . 175
        Plot  . . . . . . . . . . . . . . . . . . . . . . . . . . . 176
        Pm3d  . . . . . . . . . . . . . . . . . . . . . . . . . . . 177
        Depthorder  . . . . . . . . . . . . . . . . . . . . . . . . 182
        Palette . . . . . . . . . . . . . . . . . . . . . . . . . . 182
        Rgbformulae . . . . . . . . . . . . . . . . . . . . . . . . 185
        Defined . . . . . . . . . . . . . . . . . . . . . . . . . . 185
        Functions . . . . . . . . . . . . . . . . . . . . . . . . . 187
        File  . . . . . . . . . . . . . . . . . . . . . . . . . . . 187
        Gamma correction  . . . . . . . . . . . . . . . . . . . . . 188
        Postscript  . . . . . . . . . . . . . . . . . . . . . . . . 189
        Pointintervalbox  . . . . . . . . . . . . . . . . . . . . . 190
        Pointsize . . . . . . . . . . . . . . . . . . . . . . . . . 190
        Polar . . . . . . . . . . . . . . . . . . . . . . . . . . . 190
        Print . . . . . . . . . . . . . . . . . . . . . . . . . . . 191
        Rmargin . . . . . . . . . . . . . . . . . . . . . . . . . . 192
        Rrange  . . . . . . . . . . . . . . . . . . . . . . . . . . 192
        Samples . . . . . . . . . . . . . . . . . . . . . . . . . . 192
        Size  . . . . . . . . . . . . . . . . . . . . . . . . . . . 192










   GNUPLOT 4.1                                                       vi


        Style . . . . . . . . . . . . . . . . . . . . . . . . . . . 194
        Set style arrow . . . . . . . . . . . . . . . . . . . . . . 194
        Set style data  . . . . . . . . . . . . . . . . . . . . . . 196
        Set style fill  . . . . . . . . . . . . . . . . . . . . . . 196
        Set style fill transparent  . . . . . . . . . . . . . . . . 197
        Set style function  . . . . . . . . . . . . . . . . . . . . 198
        Set style increment . . . . . . . . . . . . . . . . . . . . 198
        Set style line  . . . . . . . . . . . . . . . . . . . . . . 199
        Set style circle  . . . . . . . . . . . . . . . . . . . . . 201
        Set style rectangle . . . . . . . . . . . . . . . . . . . . 201
        Surface . . . . . . . . . . . . . . . . . . . . . . . . . . 202
        Table . . . . . . . . . . . . . . . . . . . . . . . . . . . 202
        Terminal  . . . . . . . . . . . . . . . . . . . . . . . . . 203
        Termoption  . . . . . . . . . . . . . . . . . . . . . . . . 204
        Tics  . . . . . . . . . . . . . . . . . . . . . . . . . . . 204
        Ticslevel . . . . . . . . . . . . . . . . . . . . . . . . . 206
        Ticscale  . . . . . . . . . . . . . . . . . . . . . . . . . 206
        Timestamp . . . . . . . . . . . . . . . . . . . . . . . . . 206
        Timefmt . . . . . . . . . . . . . . . . . . . . . . . . . . 207
        Title . . . . . . . . . . . . . . . . . . . . . . . . . . . 208
        Tmargin . . . . . . . . . . . . . . . . . . . . . . . . . . 209
        Trange  . . . . . . . . . . . . . . . . . . . . . . . . . . 209
        Urange  . . . . . . . . . . . . . . . . . . . . . . . . . . 209
        Variables . . . . . . . . . . . . . . . . . . . . . . . . . 209
        Version . . . . . . . . . . . . . . . . . . . . . . . . . . 210
        View  . . . . . . . . . . . . . . . . . . . . . . . . . . . 210
        Equal_axes  . . . . . . . . . . . . . . . . . . . . . . . . 211
        Vrange  . . . . . . . . . . . . . . . . . . . . . . . . . . 211
        X2data  . . . . . . . . . . . . . . . . . . . . . . . . . . 211
        X2dtics . . . . . . . . . . . . . . . . . . . . . . . . . . 211
        X2label . . . . . . . . . . . . . . . . . . . . . . . . . . 212
        X2mtics . . . . . . . . . . . . . . . . . . . . . . . . . . 212
        X2range . . . . . . . . . . . . . . . . . . . . . . . . . . 212
        X2tics  . . . . . . . . . . . . . . . . . . . . . . . . . . 212
        X2zeroaxis  . . . . . . . . . . . . . . . . . . . . . . . . 212
        Xdata . . . . . . . . . . . . . . . . . . . . . . . . . . . 212
        Xdtics  . . . . . . . . . . . . . . . . . . . . . . . . . . 213
        Xlabel  . . . . . . . . . . . . . . . . . . . . . . . . . . 213
        Xmtics  . . . . . . . . . . . . . . . . . . . . . . . . . . 215
        Xrange  . . . . . . . . . . . . . . . . . . . . . . . . . . 216
        Xtics . . . . . . . . . . . . . . . . . . . . . . . . . . . 217
        Xtics time_data . . . . . . . . . . . . . . . . . . . . . . 221
        Xtics rangelimited  . . . . . . . . . . . . . . . . . . . . 221
        Xyplane . . . . . . . . . . . . . . . . . . . . . . . . . . 222
        Xzeroaxis . . . . . . . . . . . . . . . . . . . . . . . . . 222
        Y2data  . . . . . . . . . . . . . . . . . . . . . . . . . . 222
        Y2dtics . . . . . . . . . . . . . . . . . . . . . . . . . . 223
        Y2label . . . . . . . . . . . . . . . . . . . . . . . . . . 223
        Y2mtics . . . . . . . . . . . . . . . . . . . . . . . . . . 223
        Y2range . . . . . . . . . . . . . . . . . . . . . . . . . . 223
        Y2tics  . . . . . . . . . . . . . . . . . . . . . . . . . . 223
        Y2zeroaxis  . . . . . . . . . . . . . . . . . . . . . . . . 223
        Ydata . . . . . . . . . . . . . . . . . . . . . . . . . . . 224










   GNUPLOT 4.1                                                      vii


        Ydtics  . . . . . . . . . . . . . . . . . . . . . . . . . . 224
        Ylabel  . . . . . . . . . . . . . . . . . . . . . . . . . . 224
        Ymtics  . . . . . . . . . . . . . . . . . . . . . . . . . . 224
        Yrange  . . . . . . . . . . . . . . . . . . . . . . . . . . 224
        Ytics . . . . . . . . . . . . . . . . . . . . . . . . . . . 224
        Yzeroaxis . . . . . . . . . . . . . . . . . . . . . . . . . 224
        Zdata . . . . . . . . . . . . . . . . . . . . . . . . . . . 225
        Zdtics  . . . . . . . . . . . . . . . . . . . . . . . . . . 225
        Zzeroaxis . . . . . . . . . . . . . . . . . . . . . . . . . 225
        Cbdata  . . . . . . . . . . . . . . . . . . . . . . . . . . 225
        Cbdtics . . . . . . . . . . . . . . . . . . . . . . . . . . 225
        Zero  . . . . . . . . . . . . . . . . . . . . . . . . . . . 225
        Zeroaxis  . . . . . . . . . . . . . . . . . . . . . . . . . 226
        Zlabel  . . . . . . . . . . . . . . . . . . . . . . . . . . 227
        Zmtics  . . . . . . . . . . . . . . . . . . . . . . . . . . 227
        Zrange  . . . . . . . . . . . . . . . . . . . . . . . . . . 227
        Ztics . . . . . . . . . . . . . . . . . . . . . . . . . . . 227
        Cblabel . . . . . . . . . . . . . . . . . . . . . . . . . . 227
        Cbmtics . . . . . . . . . . . . . . . . . . . . . . . . . . 227
        Cbrange . . . . . . . . . . . . . . . . . . . . . . . . . . 227
        Cbtics  . . . . . . . . . . . . . . . . . . . . . . . . . . 228
        Shell . . . . . . . . . . . . . . . . . . . . . . . . . . . 228
        Splot . . . . . . . . . . . . . . . . . . . . . . . . . . . 228
        Data-file . . . . . . . . . . . . . . . . . . . . . . . . . 229
        Binary matrix . . . . . . . . . . . . . . . . . . . . . . . 230
        Example datafile  . . . . . . . . . . . . . . . . . . . . . 231
        Matrix_ascii  . . . . . . . . . . . . . . . . . . . . . . . 232
        Matrix  . . . . . . . . . . . . . . . . . . . . . . . . . . 233
        Grid data . . . . . . . . . . . . . . . . . . . . . . . . . 234
        Splot overview  . . . . . . . . . . . . . . . . . . . . . . 234
        System  . . . . . . . . . . . . . . . . . . . . . . . . . . 235
        Test  . . . . . . . . . . . . . . . . . . . . . . . . . . . 235
        Undefine  . . . . . . . . . . . . . . . . . . . . . . . . . 236
        Unset . . . . . . . . . . . . . . . . . . . . . . . . . . . 236
        Update  . . . . . . . . . . . . . . . . . . . . . . . . . . 236
        Terminal types  . . . . . . . . . . . . . . . . . . . . . . 237
        Complete list of terminals  . . . . . . . . . . . . . . . . 237
        Aed767  . . . . . . . . . . . . . . . . . . . . . . . . . . 237
        Aifm  . . . . . . . . . . . . . . . . . . . . . . . . . . . 237
        Amiga . . . . . . . . . . . . . . . . . . . . . . . . . . . 238
        Apollo  . . . . . . . . . . . . . . . . . . . . . . . . . . 238
        Aqua  . . . . . . . . . . . . . . . . . . . . . . . . . . . 239
        Be  . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239
        Command-line_options  . . . . . . . . . . . . . . . . . . . 240
        Monochrome_options  . . . . . . . . . . . . . . . . . . . . 241
        Color_resources . . . . . . . . . . . . . . . . . . . . . . 241
        Grayscale_resources . . . . . . . . . . . . . . . . . . . . 242
        Line_resources  . . . . . . . . . . . . . . . . . . . . . . 243
        Canvas  . . . . . . . . . . . . . . . . . . . . . . . . . . 244
        Cgi . . . . . . . . . . . . . . . . . . . . . . . . . . . . 245
        Cgm . . . . . . . . . . . . . . . . . . . . . . . . . . . . 245
        Cgm font  . . . . . . . . . . . . . . . . . . . . . . . . . 246
        Cgm fontsize  . . . . . . . . . . . . . . . . . . . . . . . 248










   GNUPLOT 4.1                                                     viii


        Cgm linewidth . . . . . . . . . . . . . . . . . . . . . . . 248
        Cgm rotate  . . . . . . . . . . . . . . . . . . . . . . . . 248
        Cgm solid . . . . . . . . . . . . . . . . . . . . . . . . . 249
        Cgm size  . . . . . . . . . . . . . . . . . . . . . . . . . 249
        Cgm width . . . . . . . . . . . . . . . . . . . . . . . . . 249
        Cgm nofontlist  . . . . . . . . . . . . . . . . . . . . . . 249
        Corel . . . . . . . . . . . . . . . . . . . . . . . . . . . 250
        Debug . . . . . . . . . . . . . . . . . . . . . . . . . . . 250
        Dospc . . . . . . . . . . . . . . . . . . . . . . . . . . . 250
        Dumb  . . . . . . . . . . . . . . . . . . . . . . . . . . . 250
        Dxf . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251
        Dxy800a . . . . . . . . . . . . . . . . . . . . . . . . . . 251
        Eepic . . . . . . . . . . . . . . . . . . . . . . . . . . . 251
        Emf . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253
        Emxvga  . . . . . . . . . . . . . . . . . . . . . . . . . . 254
        Epslatex  . . . . . . . . . . . . . . . . . . . . . . . . . 254
        Epson_180dpi  . . . . . . . . . . . . . . . . . . . . . . . 259
        Excl  . . . . . . . . . . . . . . . . . . . . . . . . . . . 260
        Fig . . . . . . . . . . . . . . . . . . . . . . . . . . . . 260
        Ggi . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262
        Gif . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262
        Examples  . . . . . . . . . . . . . . . . . . . . . . . . . 264
        Gnugraph(GNU plotutils) . . . . . . . . . . . . . . . . . . 264
        Gpic  . . . . . . . . . . . . . . . . . . . . . . . . . . . 265
        Gpr . . . . . . . . . . . . . . . . . . . . . . . . . . . . 266
        Grass . . . . . . . . . . . . . . . . . . . . . . . . . . . 266
        Hercules  . . . . . . . . . . . . . . . . . . . . . . . . . 267
        Hp2623a . . . . . . . . . . . . . . . . . . . . . . . . . . 267
        Hp2648  . . . . . . . . . . . . . . . . . . . . . . . . . . 267
        Hp500c  . . . . . . . . . . . . . . . . . . . . . . . . . . 267
        Hpgl  . . . . . . . . . . . . . . . . . . . . . . . . . . . 267
        Hpljii  . . . . . . . . . . . . . . . . . . . . . . . . . . 269
        Hppj  . . . . . . . . . . . . . . . . . . . . . . . . . . . 269
        Imagen  . . . . . . . . . . . . . . . . . . . . . . . . . . 270
        Jpeg  . . . . . . . . . . . . . . . . . . . . . . . . . . . 270
        Kyo . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271
        Latex . . . . . . . . . . . . . . . . . . . . . . . . . . . 271
        Linux . . . . . . . . . . . . . . . . . . . . . . . . . . . 272
        Lua . . . . . . . . . . . . . . . . . . . . . . . . . . . . 272
        Macintosh . . . . . . . . . . . . . . . . . . . . . . . . . 275
        Mf  . . . . . . . . . . . . . . . . . . . . . . . . . . . . 276
        METAFONT Instructions . . . . . . . . . . . . . . . . . . . 277
        Mgr . . . . . . . . . . . . . . . . . . . . . . . . . . . . 278
        Mif . . . . . . . . . . . . . . . . . . . . . . . . . . . . 278
        Mp  . . . . . . . . . . . . . . . . . . . . . . . . . . . . 279
        Metapost Instructions . . . . . . . . . . . . . . . . . . . 282
        Next  . . . . . . . . . . . . . . . . . . . . . . . . . . . 283
        Openstep (next) . . . . . . . . . . . . . . . . . . . . . . 283
        Pbm . . . . . . . . . . . . . . . . . . . . . . . . . . . . 284
        Pdf . . . . . . . . . . . . . . . . . . . . . . . . . . . . 284
        Pdfcairo  . . . . . . . . . . . . . . . . . . . . . . . . . 285
        Pm  . . . . . . . . . . . . . . . . . . . . . . . . . . . . 287
        Png . . . . . . . . . . . . . . . . . . . . . . . . . . . . 288










   GNUPLOT 4.1                                                       ix


        Examples  . . . . . . . . . . . . . . . . . . . . . . . . . 289
        Pngcairo  . . . . . . . . . . . . . . . . . . . . . . . . . 289
        Postscript  . . . . . . . . . . . . . . . . . . . . . . . . 291
        Editing postscript  . . . . . . . . . . . . . . . . . . . . 294
        Postscript fontfile . . . . . . . . . . . . . . . . . . . . 295
        Postscript prologue . . . . . . . . . . . . . . . . . . . . 297
        Postscript adobeglyphnames  . . . . . . . . . . . . . . . . 297
        Pslatex and pstex . . . . . . . . . . . . . . . . . . . . . 298
        Pstricks  . . . . . . . . . . . . . . . . . . . . . . . . . 300
        Qms . . . . . . . . . . . . . . . . . . . . . . . . . . . . 301
        Regis . . . . . . . . . . . . . . . . . . . . . . . . . . . 301
        Rgip  . . . . . . . . . . . . . . . . . . . . . . . . . . . 301
        Sun . . . . . . . . . . . . . . . . . . . . . . . . . . . . 302
        Svg . . . . . . . . . . . . . . . . . . . . . . . . . . . . 302
        Svga  . . . . . . . . . . . . . . . . . . . . . . . . . . . 303
        Tek40 . . . . . . . . . . . . . . . . . . . . . . . . . . . 303
        Tek410x . . . . . . . . . . . . . . . . . . . . . . . . . . 303
        Texdraw . . . . . . . . . . . . . . . . . . . . . . . . . . 303
        Tgif  . . . . . . . . . . . . . . . . . . . . . . . . . . . 304
        Tikz  . . . . . . . . . . . . . . . . . . . . . . . . . . . 305
        Tkcanvas  . . . . . . . . . . . . . . . . . . . . . . . . . 305
        Tpic  . . . . . . . . . . . . . . . . . . . . . . . . . . . 306
        Unixpc  . . . . . . . . . . . . . . . . . . . . . . . . . . 307
        Unixplot  . . . . . . . . . . . . . . . . . . . . . . . . . 307
        Vgagl . . . . . . . . . . . . . . . . . . . . . . . . . . . 307
        VWS . . . . . . . . . . . . . . . . . . . . . . . . . . . . 308
        Vx384 . . . . . . . . . . . . . . . . . . . . . . . . . . . 309
        Windows . . . . . . . . . . . . . . . . . . . . . . . . . . 309
        Graph-menu  . . . . . . . . . . . . . . . . . . . . . . . . 310
        Printing  . . . . . . . . . . . . . . . . . . . . . . . . . 310
        Text-menu . . . . . . . . . . . . . . . . . . . . . . . . . 311
        Wgnuplot.ini  . . . . . . . . . . . . . . . . . . . . . . . 312
        Wxt . . . . . . . . . . . . . . . . . . . . . . . . . . . . 313
        X11 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 315
        X11_fonts . . . . . . . . . . . . . . . . . . . . . . . . . 317
        Command-line_options  . . . . . . . . . . . . . . . . . . . 319
        Monochrome_options  . . . . . . . . . . . . . . . . . . . . 320
        Color_resources . . . . . . . . . . . . . . . . . . . . . . 320
        Grayscale_resources . . . . . . . . . . . . . . . . . . . . 321
        Line_resources  . . . . . . . . . . . . . . . . . . . . . . 322
        X11 pm3d_resources  . . . . . . . . . . . . . . . . . . . . 323
        X11 other_resources . . . . . . . . . . . . . . . . . . . . 324
        Xlib  . . . . . . . . . . . . . . . . . . . . . . . . . . . 325
        Graphical User Interfaces . . . . . . . . . . . . . . . . . 325
        Bugs  . . . . . . . . . . . . . . . . . . . . . . . . . . . 325
        Gnuplot limitations . . . . . . . . . . . . . . . . . . . . 326
        External libraries  . . . . . . . . . . . . . . . . . . . . 326












