Returns the gradient as a callable function of (functions of) QNodes.
Function arguments with the property
Falsewill automatically be excluded from the gradient computation, unless the
argnumkeyword argument is passed.
When the output gradient function is executed, both the forward pass and the backward pass will be performed in order to compute the gradient. The value of the forward pass is available via the
func (function) – a plain QNode, or a Python function that contains a combination of quantum and classical nodes
argnum (int, list(int), None) – Which argument(s) to take the gradient with respect to. By default, the arguments themselves are used to determine differentiability, by examining the
The function that returns the gradient of the input function with respect to the differentiable arguments, or, if specified, the arguments in
- Return type
The result of the forward pass calculated while performing backpropagation.
The result of the forward pass calculated while performing backpropagation. Will return
Noneif the backpropagation has not yet been performed.