Scilab is a scientific software package for numerical computations including:
 * Elaborate data structures (polynomial, rational and string matrices, lists,
   multivariable linear systems,...).
 * Sophisticated interpreter and programming language with Matlab-like syntax.
 * Hundreds of built-in math functions (new primitives can easily be added).
 * Stunning graphics (2d, 3d, animation).
 * Open structure (easy interfacing with Fortran and C via online dynamic
   link).
 * Many built-in libraries:
    + Linear Algebra (including sparse matrices, Kronecker form, 
      ordered Schur,...).
    + Control (Classical, LQG, H-infinity,...).
    + Package for LMI (Linear Matrix Inequalities) optimization.
    + Signal processing.
    + Simulation (various ode's, dassl,...).
    + Optimization (differentiable and non-differentiable, LQ solver).
    + Scicos, an interactive environment for modeling and simulation of 
      hybrid systems.
    + Metanet (network analysis and optimization).
 * Symbolic capabilities through Maple interface.
 * Parallel Scilab.
For more information about Scilab, send an e-mail to Doctor Scilab: 
Scilab@inria.fr