A simulation software under GPL licence for MacOS X

The software Scilab, available under GPL licence (for the ones who know it it is equivalent to Matlab), was compiled under GTK and is now available at the following address :
http://www.lmac.utc.fr/~mottelet/Darwin/.
Using the XMLlab software, also under GPL licence (http://www.xmllab.org) it will enable you to make simulations, from simple ones to the most complex.