Octave – or is it Matlab? …well maybe not, yet.

GNU Octave is a high-level language, primarily intended for numerical computations. It provides a convenient command line interface for solving linear and nonlinear problems numerically, and for performing other numerical experiments using a language that is mostly compatible with Matlab. It may also be used as a batch-oriented language for settings where long running programs are required. It is useful to think of Octave as a free alternative to Matlab. The community of users is large and productive, resulting in many freely available programs based on Octave. Visit the homepage at:
http://www.gnu.org/software/octave/