sympy/sympy — pull request #783 by Timeroot (2011-11-29 07:22:30+00:00)
Title: Modified inverse_GE() to use rref() instead of det()

As mentioned at http://groups.google.com/group/sympy/browse_thread/thread/ba37b597b851df7c# and http://code.google.com/p/sympy/issues/detail?id=2683
inverse_GE(), the default method for matrix inversion, was calling det() to check for inversion; this greatly damaged performance. It was replaced with a call to rref().