zanzibar7/sympy — pull request #2 by jrioux (2013-08-23 22:47:26+00:00)
Title: Catch symbolic relational error in Sum.evalf().

Partly fixes issues 3229. The remaining part has to do with the .evalf() call when printing. This happens because Sum(f(x), (x, 1, 3)).is_number is True which, according to current definitions, seems correct.

http://code.google.com/p/sympy/issues/detail?id=3229