GNU Octave

GNU Octave is a free and open-source software and high-level interactive language for numerical computations.

Octave packages
Octave's functionality (i.e. selection of functions available to the user in octave) is extended via octave-packages [1], usually provided by octave-forge [2]. There are two ways to install octave packages:
 * Use octave's own "pkg" command to install missing packages
 * Use "app-portage/g-octave" to generate ebuilds for octave-packages from Octave-Forge and install them via portage

There is conflicting information about which method to prefer [3][4], so no recommendation can be given at this point.

[1] http://octave.sourceforge.net/packages.php

[2] http://octave.sourceforge.net/index.html

[3] http://wiki.octave.org/Octave-Forge#Installing_packages

[4] http://wiki.octave.org/Octave_for_GNU/Linux#Gentoo