Gnuplot plots any number of functions, built up of C operators, C library functions, and some things C doesn't have like **, sgn(), etc. There is also support for plotting data files, to com- pare actual data to theoretical curves.
Some of the features of Gnuplot are:
You can look at examples to see a sampler of what can be done. For how to access Gnuplot on the supported systems, see NERSC J90 or UNIX or VMS.