Scilab Function
Last update : 16/12/2004

plot2d_old_version - 2D plot reference

### Calling Sequence

  `plot2d([x],y)`
  `plot2d([x],y,<opt_args>) (new syntax)`
  `plot2d([logflag],x,y,[style,strf,leg,rect,nax]) (old syntax)`

### Parameters

- `x,y`: two matrices (or column vectors).
  - ``in the usual way `x` is a matrix of the same size than `y` (the column j of `y` is plotted with respect to column j of `x`)
  - ``if all the columns of `x` are equal (ie the abscissae of all the curves are the same), `x` may be simply the (column) vector of these abscissae (`x` is then a column vector of length equal to the row dimension of `y`).
  - ``when `x` is not given, it is supposed to be the column vector [1; 2; ...; row dimension of y].
- `<opt_args>`: This represents a sequence of statements `key1=value1, key2=value2`,... where `key1`, `key2,...` can be one of the following:
  - `style`: sets the style for each curve, see below for value.
  - `leg`: sets the curves captions. If this key is given and `strf` is not given then `x` character of `strf` is supposed to be `1`. See below for value.
  - `rect`: sets the bounds of the plot. If this key is given and neither `frameflag` nor `strf` is given then the `y` character of `strf` is supposed to be `7`. See below for value.
  - `nax`: sets the grids definition. If this key is given and neither `axesflag` nor `strf` is given then the `z` character of `strf` is supposed to be `1`. See below for value.
  - `logflag`: sets the scale (linear or logarithmic) along the axes. See below for value.
  - `frameflag`: specifies how the frame of the plot is computed. The value is an integer ranging from 0 to 8. It corresponds to the `y` character of `strf`. See below.
  - `axesflag`: specifies what kind of axes are drawn around the plot. The value is an integer ranging from 0 to 5. It corresponds to the `z` character of `strf`. See below.
- `style`: is a real row vector of size nc. The style to use for curve `i` is defined by `style(i)`. The default style is `1:nc` (1 for the first curve, 2 for the second, etc.).
  - `-`if `style(i)` is negative or zero, the curve is plotted using the mark with id `abs(style(i))`; use `xset()` to set the mark id and xget('mark') to get the current mark id.
  - `-`if `style(i)` is strictly positive, a plain line with color id `style(i)` or a dashed line with dash id `style(i)` is used; use `xset()` to see the color ids.
  - `-`When only one curve is drawn, `style` can be the row vector of size 2 `[sty,pos]` where `sty` is used to specify the style and `pos` is an integer ranging from 1 to 6 which specifies a position to use for the caption. This can be useful when a user wants to draw multiple curves on a plot by calling the function `plot2d` several times and wants to give a caption for each curve.
- `strf`: is a string of length 3 `"xyz"` (by default `strf= "081"`)
  - `x`: controls the display of captions.
    - `x=0`: no caption.
    - `x=1`: captions are displayed. They are given by the optional argument `leg`.
  - `y`: controls the computation of the actual coordinate ranges from the minimal requested values. Actual ranges can be larger than minimal requirements.
    - `y=0`: no computation, the plot use the previus (or default) scale
    - `y=1`: from the rect arg
    - `y=2`: from the min/max of the x, y datas
    - `y=3`: built for an isometric scale from the rect arg
    - `y=4`: built for an isometric plot from the min/max of the x, y datas
    - `y=5`: enlarged for pretty axes from the rect arg
    - `y=6`: enlarged for pretty axes from the min/max of the x, y datas
    - `y=7`: like y=1 but the previus plot(s) are redrawn to use the new scale
    - `y=8`: like y=2 but the previus plot(s) are redrawn to use the new scale
  - `z`: controls the display of information on the frame around the plot. If axes are requested, the number of tics can be specified by the `nax` optional argument.
    - `z=0`: nothing is drawn around the plot.
    - `z=1`: axes are drawn, the y=axis is displayed on the left.
    - `z=2`: the plot is surrounded by a box without tics.
    - `z=3`: axes are drawn, the y=axis is displayed on the right.
    - `z=4`: axes are drawn centred in the middle of the frame box.
    - `z=5`: axes are drawn so as to cross at point `(0,0)`. If point `(0,0)` does not lie inside the frame, axes will not appear on the graph.
- `leg`: a string. It is used when the first character x of argument `strf` is 1. `leg` has the form `"leg1@leg2@...."` where `leg1`, `leg2`, etc. are respectively the captions of the first curve, of the second curve, etc. The default is `""`.
- `rect`: This argument is used when the second character y of argument `strf` is 1, 3 or 5. It is a row vector of size 4 and gives the dimension of the frame: `rect=[xmin,ymin,xmax,ymax]`.
- `nax`: This argument is used when the third character z of argument `strf` is 1. It is a row vector with four entries `[nx,Nx,ny,Ny]` where `nx` (`ny`) is the number of subgraduations on the x (y) axis and `Nx` (`Ny`) is the number of graduations on the x (y) axis.
- `logflag`: a string formed by to characters h (for horizontal axis) and v (for vertical axis) each of these characters can take the values "n" or "l". "l" stands for logarithmic graduation and "n" for normal graduation. For example "ll"stands for a log-log plot. Default value is "nn".

### Description

`plot2d` plots a set of 2D curves. Piecewise linear plotting is used.

By default, successive plots are superposed. To clear the previous plot, use `xbasc()`.

See the meaning of the parameters above for a complete description.

Enter the command `plot2d()` to see a demo.

Other high level plot2d function exist:

  plot2d2: same as `plot2d` but the curve is supposed to be piecewise constant.
  plot2d3: same as `plot2d` but the curve is plotted with vertical bars.
  plot2d4: same as `plot2d` but the curve is plotted with arrows.

### Examples

    //simple plot
    x=[0:0.1:2*%pi]';
    plot2d(sin(x))
    xbasc()
    plot2d(x,sin(x))
    //multiple plot
    xbasc()
    plot2d(x,[sin(x) sin(2*x) sin(3*x)])
    // multiple plot giving the dimensions of the frame
    // old syntax and new syntax
    xbasc()
    plot2d(x,[sin(x) sin(2*x) sin(3*x)],1:3,"011","",[0,0,6,0.5])
    xbasc()
    plot2d(x,[sin(x) sin(2*x) sin(3*x)],rect=[0,0,6,0.5])
    //multiple plot with captions and given tics // old syntax and new syntax
    xbasc()
    plot2d(x,[sin(x) sin(2*x) sin(3*x)],..
      [1,2,3],"111","L1@L2@L3",[0,-2,2*%pi,2],[2,10,2,10]);
    xbasc()
    plot2d(x,[sin(x) sin(2*x) sin(3*x)],..
      [1,2,3],leg="L1@L2@L3",nax=[2,10,2,10],rect=[0,-2,2*%pi,2])
    // isoview
    xbasc()
    plot2d(x,sin(x),1,"041")
    // scale
    xbasc()
    plot2d(x,sin(x),1,"061")
    // auto scaling with previous plots
    xbasc()
    plot2d(x,sin(x),1)
    plot2d(x,2*sin(x),2)
    plot2d(2*x,cos(x),3)
    // axis on the right
    xbasc()
    plot2d(x,sin(x),1,"183","sin(x)")
    // centered axis
    xbasc()
    plot2d(x,sin(x),1,"184","sin(x)")
    // axis centered at (0,0)
    xbasc()
    plot2d(x-4,sin(x),1,"185","sin(x)")

### See Also

`plot2d1`, `plot2d2`, `plot2d3`, `plot2d4`, `xbasc`, `xset`,

### Author

J.Ph.C.