Theano/Theano — pull request #224 by vlb (2011-11-24 00:07:28+00:00)
Title: Reviewed and filled the gaps in sparse sum op (SpSum)

Side note: the code in the perform method might be a bit more generic than the case by case (self.axis=None/0/1) code that I left in comment, but less readable. Keep the one you like.