See also DebianScienceGnuplot.
Gnuplot -- Web: http://www.gnuplot.info/
Description
A command-line driven interactive plotting program, in 2D and 3D.
Presentation in French :
http://logiciels-libres-cndp.ac-versailles.fr/article.php3?id_article=70&var_recherche=gnuplot
.