Registers a backward hook.
The hook will be called every time a gradient with respect to the Tensor is computed. The hook should have the following signature:
hook(grad) -> Tensor or None
The hook should not modify its argument, but it can optionally return a new gradient which will be used in place of
This function returns a handle with a method
handle.remove()that removes the hook from the module.
See Backward Hooks execution for more information on how when this hook is executed, and how its execution is ordered relative to other hooks.
>>> v = torch.tensor([0., 0., 0.], requires_grad=True) >>> h = v.register_hook(lambda grad: grad * 2) # double the gradient >>> v.backward(torch.tensor([1., 2., 3.])) >>> v.grad 2 4 6 [torch.FloatTensor of size (3,)] >>> h.remove() # removes the hook