Given logits Z (n, k) and integer labels y (n,), return the (n, k) array dL/dZ where L is the mean softmax cross-entropy loss.
Input
Z =
[[1. 2. 3.]
[3. 1. 0.]]
y = [2 0]
Output
[[ 0.04501529 0.12236424 -0.16737952]
[-0.07810263 0.0570976 0.02100503]]