There's also FreeMat http://freemat.sourceforge.net/ http://freemat.sourceforge.net/ which at the time had much better Matlab compatibility than Octave, and a m

There's also FreeMat http://freemat.sourceforge.net/ http://freemat.sourceforge.net/ which at the time had much better Matlab compatibility than Octave, and a much better GUI (comparable to Matlab's circa 2007 or so, which was when I compared them). And for some reason, it was virtually unknown - Octave is superfamous compated to FreeMat.