NAME

Gnuplot − a command driven interactive plotting program. 

SYNOPSIS

gnuplot [ options ]

DESCRIPTION

Gnuplot is a command driven, interactive plotting program which can draw graphs either an X11 window or into a Postscript file which can then be printed on a Postscript-using printer.  Output drivers for several other kinds of hardcopy plotters and personal computer graphic displays are also available. 

It is extremely simple to display graphs of mathematical functions using gnuplot.  For example, if you want to view the parabola defined by the equation:
 
 y = x^2
 
then, after entering gnuplot and receiving the prompt "gnuplot>", simply type:
 
 plot x∗∗2
 
(gnuplot, like Fortran, uses the syntax x∗∗y to denote exponentation).

The X values plotted range by default from -10 to +10.  The graph scaling in both the X and Y directions is done automatically according to the values that need to be plotted. 

Different commands exist to change the plotting style, manually set ranges and scaling, change output devices, etc.  Also, there is a fairly good library of mathematical functions.  All of these functions work in the complex plane, as gnuplot does all of its calculations using complex numbers.  (Only real numbers actually get plotted, though.  Complex domain plotting waits for a future enhancement). 

There is a built in help system which you can access by typing "help" to the "gnuplot>" prompt.  Typing "help ?" lists all the topics that the help system knows about.  Examining the help for each of the topics, in the order that "help ?" lists them, shows you all of the material in the printed gnuplot manual. 

gnuplot was written by Thomas Williams and Colin Kelley at Villanova University in Pennsylvania.  The X window driver and some other features were added at MIT.  There is at the moment no connection between the original gnuplot authors and the GNU project of the Free Software Foundation Inc.  gnuplot’s name might have been chosen because the authors intend to contribute the program to the GNU project someday, or it might be a coincidence.  All attempts to date to get in touch with them and get this question answered have failed. 

HARD COPY

Gnuplot will can formats plots for a postscript printer and send them to a file, the commands to do this are:
 
gnuplot> set terminal postscript
gnuplot> set output "<filename>"
gnuplot> replot
gnuplot> set terminal xwindow
 
The quotation marks are important.  You may now simply print the file on a postscript printer.

OPTIONS

host:display
Normally, Gnuplot gets the host and display number to use from the environment variable “DISPLAY”.  One can, however specify them explicitly.  The host specifies which machine to create the window on, and the number argument specifies the display number.  For example, “orpheus:1” creates a shell window on display one on the machine orpheus. 

−d print standard .Xdefaults
The ’default’ .Xdefaults will be printed to standard out.  You may then change the values to suit your particular needs.

−f fontname Set the Font
This sets the font used for the text.

−r reverse video
The foreground and background colors will be switched.  The default colors are black on white.

X DEFAULTS

Gnuplot uses a number of standard default values. 

ReverseVideo
If ‘on’, reverse the definition of foreground and background color.

Geometery
This uses a standard geometry string to set the position of the window that contains the plot.  The height and width fields are ignored.

Font
The font to be used for all text in the plot window.

BUGS

There probabally are some. 

AUTHOR

Thomas Williams, Colin Kelley
Copyright (C) 1986, 1987  Thomas Williams, Colin Kelley.
X Window Driver added by Paul Ruben (MIT - Project Athena).
X Defaults and command line options added by Chris Peterson (MIT - Project Athena).

September 29, 2021