Hi Wenjie!



 Wenjie_Qiang:

will gradients flow correctly to the weights of conv


No.  scatter_add_() requires that its index argument be a tensor
of type int64.  Gradients don’t (and can’t) flow back through integers.
(Gradients will flow back through self (your p) and src (your data)
if they have requires_grad = True.)
Best.
K. Frank