1. A command-line driven interactive plotting program. Package for making 2D and 3D graphs from data and functions. Supports lots of output formats, including drivers for many printers, (La)TeX, (x)fig, X11, PostScript, and so on. Data files and self-defined functions can be manipulated by internal C-like language. Can perform smoothing, spline-fitting, or nonlinear fits. Can work with complex numbers. From Debian 3.0r0 APT

2. Gnuplot is a command-line driven, interactive function plotting programespecially suited for scientific data representation. Gnuplot can be used to plot functions and data points in both two and three dimensions and in many different formats. Install gnuplot if you need a graphics package for scientific data representation. From Mandrake 9.0 RPM