Gnuplot

Gnuplot is a portable command-line driven graphing utility for Linux, OS/2, MS Windows, OSX, VMS, and many other platforms. The source code is copyrighted but freely distributed (i.e., you don't have to pay for it). It was originally created to allow scientists and students to visualize mathematical functions and data interactively, but has grown to support many non-interactive uses such as web scripting. It is also used as a plotting engine by third-party applications like Octave. Gnuplot has been supported and under active development since 1986.

# Usage

$ gnuplot
gnuplot> set terminal dumb
gnuplot> help

Gnuplot can also be used in combination with SC-IM, the Vim-based terminal spreadsheet calculator.

See a demo gallery at http://gnuplot.sourceforge.net/demo_5.5/.