PLplot is a library of functions that are useful for making scientific plots. PLplot can be used from within compiled languages such as C, C++, Fortran and Java, and interactively from interpreted languages such as Octave, Python, Perl and Tcl. The PLplot library can be used to create standard x-y plots, semilog plots, log-log plots, contour plots, 3D surface plots, mesh plots, bar charts and pie charts. Multiple graphs (of the same or different sizes) may be placed on a single page with multiple lines in each graph. A variety of output file devices such as Postscript, png, jpeg, LaTeX and others, as well as interactive devices such as xwin, tk, xterm and Tektronics devices are supported. New devices can be easily added by writing a small number of device dependent routines. There are almost 2000 characters in the extended character set. This includes four different fonts, the Greek alphabet and a host of mathematical, musical, and other symbols. Some devices support their own way of dealing with text, such as the Postscript and LaTeX drivers, or the png and jpeg drivers that use the Freetype library.
WWW: http://plplot.sourceforge.net/