return value of backward in class Sum about module-3 HOT 2 CLOSED

I just realized the case 2 in function 'expand' is exactly to tackle the problem aroused by the inconsistence between origin shape and gradient shape which is caused by the return value.

        # Case 2: Backward is a smaller than self. Broadcast up.
        true_shape = TensorData.shape_broadcast(self.shape, other.shape)
        buf = self.zeros(true_shape)
        self.backend._id_map(other, out=buf)
        if self.shape == true_shape:
            return buf

I'm sorry to trouble you.

from module-3.

Thanks. Yes, this is not well documented. Just kind of snuck it in the fix this issue.

from module-3.