What is the mechanism of automatic differentiation in PyTorch?

The automatic differentiation mechanism in PyTorch refers to the built-in automatic gradient calculation function, which can automatically compute the gradients of each parameter in the neural network, enabling the implementation of backpropagation and optimization algorithms. By using this mechanism, users do not need to manually calculate the gradients of each parameter in the network as PyTorch automates this process, greatly simplifying the training of neural networks. The automatic differentiation mechanism in PyTorch is based on computational graphs, where users only need to define the graph and then call the backward() method to compute and update the gradients.