added numpy source reference for dimshuffle

theano/tensor/elemwise.py

@@ -218,7 +218,8 @@ class DimShuffle(Op):
             ('strides['+str(i)+'] = 0')
             for i, o in enumerate(self.new_order)]
 
-        #set the strides of the broadcasted dimensions
+        # set the strides of the broadcasted dimensions
+        # this algorithm is from numpy: PyArray_Newshape() in cvs/numpy/numpy/core/src/multiarraymodule.c
         strides_statements.append('if (strides['+str(nd_out)+'-1] == 0) strides['+str(nd_out)+'-1] = %(basename)s->descr->elsize')
         for i in xrange(nd_out-2,-1, -1):
             strides_statements.append("if (strides[%(i)s] == 0) strides[%(i)s] = strides[%(i)s+1] * dimensions[%(i)s+1]"%dict(i=str(i)))