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, Postscript, and so on. The X11-output is packaged in gnuplot-x11. 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.