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# gnuplot

The gnuplot script supports the creation of gnuplot graphics from data generated in J.

They work with gnuplot V4.0 or later, and may work with earlier versions.

The original script was contributed by L. Fraser Jackson.

To access:

       load 'gnuplot'

# Output

When gnuplot is run it creates two files, by default in the ~temp directory:

`gnu.plt` - plot commands

`gnu.dat` - data

To display the plot, load gnuplot, then enter, using the correct path name:

       load "gnu.plt"

In Windows, you can configure gnuplot to do this automatically.

# Method

There are 3 main functions: gplot, gsplot, gset.

[cmd] gplot data

Plots 2D graphics

`data` is either as an open array for a single plot, or a a boxed list for multiple plots. This has the same format as for Plot.

`cmd` is options in a list delimited by , in gnuplot format, except that keywords should be spelled in full, e.g. use `title` not `t`.

There may be one option list per plot.

The first option list may start with a range indication. The last option list applies thereafter

[cmd] gsplot data

Plots surface graphics. The arguments are as for gplot.

gset optionlist

Set one or more gnuplot options, in gnuplot format. You can set more than one option at a time, by delimiting each option with ; .

# Use in Windows

In Windows, define `GNUPLOTBIN_jgnuplot_` as the name of the gnuplot bin directory. A good place to define this is your startup script.

If defined, then:

- the contents of gnuplot.ini are prefixed to the output file. This ensures the default values are read on start up.
- wgnuplot.exe is called after generating the plot files.

In particular, the default style for data in gnuplot is points. To change this to lines, add the following to gnuplot.ini:

      set style data lines

# Notes

Titles default to empty

You can use the double quote character to delimit strings, e.g.

      gset 'title "mydata"'

instead of:

      gset 'title ''mydata'''

Strings must be delimited, i.e. not:

      gset 'title mydata'

You can define `GNUPLOTOUT_jgnuplot_` as the output directory for files written by J. By default this is ~temp.

# Demos

      load '~system\examples\graphics\gnuplot\gpdemo.ijs'

      gp1''     NB. also gp2, gp3, gp4

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