This might sound a little basic but while running the code below, I wanted to see the source code of the backward function:
import torch.nn as nn [...] criterion = nn.CrossEntropyLoss() loss = criterion(output, target) loss.backward()
So I went to the PyTorch GitHub and found the CrossEntropyLoss class, but without any backward function defined. Moving up, CrossEntropyLoss extends _WeightedLoss >> _Loss >> Module then still nothing.
So, where is the backward function defined?