https://sourceforge.net/projects/maxima/files/Maxima-Windows/5.37.3-Windows/
http://www.sagemath.org/
http://www.scilab.org/
http://freemat.sourceforge.net/
http://mathics.github.io/
http://gamma.sympy.org/
http://peterwittek.com/spyder-closer-to-a-mathematica-alternative.html
