Wikipedia
ScicosLab
ScicosLab is a software package providing a multi-platform environment for scientific computation. It is based on the official Scilab 4.x (BUILD4) distribution, and includes the modeling and simulation tool Scicos and a number of other toolboxes.
The latest stable version of ScicosLab is ScicosLab 4.4.2.
It is possible that Scilab/Scicos is currently the most complete alternative to commercial packages for dynamic systems modeling and simulation packages such as MATLAB/ Simulink and MATRIXx/SystemBuild."