The commands for graphing data begin with the g prefix key. Calc uses GNUPLOT 2.0 or later to do graphics. These commands will only work if GNUPLOT is available on your system. (While GNUPLOT sounds like a relative of GNU Emacs, it is actually completely unrelated. However, it is free software. It can be obtained from ‘http://www.gnuplot.info’.)
If you have GNUPLOT installed on your system but Calc is unable to
find it, you may need to set the calc-gnuplot-name variable in
your Calc init file or .emacs. You may also need to set some
Lisp variables to show Calc how to run GNUPLOT on your system; these
are described under g D and g O below. If you are using
the X window system or MS-Windows, Calc will configure GNUPLOT for you
automatically. If you have GNUPLOT 3.0 or later and you are using a
Unix or GNU system without X, Calc will configure GNUPLOT to display
graphs using simple character graphics that will work on any
POSIX-compatible terminal.