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# 33. Miscellaneous Options

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## 33.1 Introduction to Miscellaneous Options

In this section various options are discussed which have a global effect on the operation of Maxima. Also various lists such as the list of all user defined functions, are discussed.

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## 33.2 Share

The Maxima "share" directory contains programs and other files of interest to Maxima users, but not part of the core implementation of Maxima. These programs are typically loaded via `load` or `setup_autoload`.

`:lisp *maxima-sharedir*` displays the location of the share directory within the user's file system.

`printfile ("share.usg")` prints an out-of-date list of share packages. Users may find it more informative to browse the share directory using a file system browser.

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## 33.3 Functions and Variables for Miscellaneous Options

System variable: askexp

  When `asksign` is called, `askexp` is the expression `asksign` is testing.

  At one time, it was possible for a user to inspect `askexp` by entering a Maxima break with control-A.

  Categories: Declarations and inferences

Option variable: genindex

  Default value: `i`

  `genindex` is the alphabetic prefix used to generate the next variable of summation when necessary.

  Categories: Sums and products

Option variable: gensumnum

  Default value: 0

  `gensumnum` is the numeric suffix used to generate the next variable of summation. If it is set to `false` then the index will consist only of `genindex` with no numeric suffix.

  Categories: Sums and products

Function: gensym ()
Function: gensym (x)

  `gensym()` creates and returns a fresh symbol.

  The name of the new-symbol is the concatenation of a prefix, which defaults to "g", and a suffix, which is the decimal representation of a number that defaults to the value of a Lisp internal counter.

  If x is supplied, and is a string, then that string is used as a prefix instead of "g" for this call to gensym only.

  If x is supplied, and is an integer, then that integer, instead of the value of the internal Lisp integer, is used as the suffix for this call to gensym only.

  If and only if no explicit suffix is supplied, the Lisp internal integer is incremented after it is used.

  Examples:

      (%i1) gensym();
      (%o1)                         g887
      (%i2) gensym("new");
      (%o2)                        new888
      (%i3) gensym(123);
      (%o3)                         g123

Option variable: packagefile

  Default value: `false`

  Package designers who use `save` or `translate` to create packages (files) for others to use may want to set `packagefile: true` to prevent information from being added to Maxima's information-lists (e.g. `values`, `functions` ) except where necessary when the file is loaded in. In this way, the contents of the package will not get in the user's way when he adds his own data. Note that this will not solve the problem of possible name conflicts. Also note that the flag simply affects what is output to the package file. Setting the flag to `true` is also useful for creating Maxima init files.

  Categories: Translation flags and variables

Function: remvalue (name_1, …, name_n)
Function: remvalue (all)

  Removes the values of user variables name_1, …, name_n (which can be subscripted) from the system.

  `remvalue (all)` removes the values of all variables in `values`, the list of all variables given names by the user (as opposed to those which are automatically assigned by Maxima).

  See also `values`.

  Categories: Evaluation

Function: rncombine (expr)

  Transforms expr by combining all terms of expr that have identical denominators or denominators that differ from each other by numerical factors only. This is slightly different from the behavior of `combine`, which collects terms that have identical denominators.

  Setting `pfeformat: true` and using `combine` yields results similar to those that can be obtained with `rncombine`, but `rncombine` takes the additional step of cross-multiplying numerical denominator factors. This results in neater forms, and the possibility of recognizing some cancellations.

  `load(rncomb)` loads this function.

  Categories: Expressions

Function: setup_autoload (filename, function_1, …, function_n)

  Specifies that if any of function_1, …, function_n are referenced and not yet defined, filename is loaded via `load`. filename usually contains definitions for the functions specified, although that is not enforced.

  `setup_autoload` does not work for array functions.

  `setup_autoload` quotes its arguments.

  Example:

      (%i1) legendre_p (1, %pi);
      (%o1)                  legendre_p(1, %pi)
      (%i2) setup_autoload ("specfun.mac", legendre_p, ultraspherical);
      (%o2)                         done
      (%i3) ultraspherical (2, 1/2, %pi);
      Warning - you are redefining the Macsyma function ultraspherical
      Warning - you are redefining the Macsyma function legendre_p
                                  2
                       3 (%pi - 1)
      (%o3)            ------------ + 3 (%pi - 1) + 1
                            2
      (%i4) legendre_p (1, %pi);
      (%o4)                          %pi
      (%i5) legendre_q (1, %pi);
                                    %pi + 1
                            %pi log(-------)
                                    1 - %pi
      (%o5)                 ---------------- - 1
                                   2

  Categories: Function definition · File input

Function: tcl_output (list, i0, skip)
Function: tcl_output (list, i0)
Function: tcl_output ([list_1, …, list_n], i)

  Prints elements of a list enclosed by curly braces `{ }`, suitable as part of a program in the Tcl/Tk language.

  `tcl_output (list, i0, skip)` prints list, beginning with element i0 and printing elements `i0 + skip`, `i0 + 2 skip`, etc.

  `tcl_output (list, i0)` is equivalent to `tcl_output (list, i0, 2)`.

  `tcl_output ([list_1, ..., list_n], i)` prints the i'th elements of list_1, …, list_n.

  Examples:

      (%i1) tcl_output ([1, 2, 3, 4, 5, 6], 1, 3)$

       {1.000000000     4.000000000
       }
      (%i2) tcl_output ([1, 2, 3, 4, 5, 6], 2, 3)$

       {2.000000000     5.000000000
       }
      (%i3) tcl_output ([3/7, 5/9, 11/13, 13/17], 1)$

       {((RAT SIMP) 3 7) ((RAT SIMP) 11 13)
       }
      (%i4) tcl_output ([x1, y1, x2, y2, x3, y3], 2)$

       {$Y1 $Y2 $Y3
       }
      (%i5) tcl_output ([[1, 2, 3], [11, 22, 33]], 1)$

       {SIMP 1.000000000     11.00000000
       }

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