Esempio n. 1
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def backward(
    outputs: Union[Tensor, Sequence[Tensor]],
    out_grads: Union[Tensor, Sequence[Tensor], None],
    retain_graph: bool = False,
    create_graph: bool = False,
) -> None:
    backward_api(
        convert_to_tensor_tuple(outputs),
        convert_to_tensor_tuple(out_grads),
        retain_graph,
        create_graph,
    )
Esempio n. 2
0
def backward(
    tensors: Union[Tensor, Sequence[Tensor]],
    grad_tensors: Union[Tensor, Sequence[Tensor], None],
    retain_graph: bool = False,
    create_graph: bool = False,
) -> None:
    r"""
    The documentation is referenced from:
    https://pytorch.org/docs/1.10/generated/torch.autograd.backward.html.

    Computes the sum of gradients of given tensors with respect to graph leaves.

    The graph is differentiated using the chain rule. If any of ``tensors`` are non-scalar (i.e.
    their data has more than one element) and require gradient, then the Jacobian-vector product
    would be computed, in this case the function additionally requires specifying ``grad_tensors``.
    It should be a sequence of matching length, that contains the "vector" in the Jacobian-vector
    product, usually the gradient of the differentiated function w.r.t. corresponding tensors.
    (``None`` is an acceptable value for all tensors that don't need gradient.)

    This function accumulates gradients in the leaves - you might need to zero ``.grad`` attributes
    or set them to ``None`` before calling it.

    Note:
        Using this method with ``create_graph=True`` will create a reference cycle between the
        parameter and its gradient which can cause a memory leak. We recommend using
        ``autograd.grad`` when creating the graph to avoid this. If you have to use this function,
        make sure to reset the ``.grad`` fields of your parameters to ``None`` after use to break
        the cycle and avoid the leak.

    Args:
        tensors (Tensor or Sequence[Tensor]): Tensors of which the derivative will be computed.
        grad_tensors (Tensor or Sequence[Tensor], optional): The "vector" in the Jacobian-vector
            product, usually gradients each element of corresponding tensors. (None values can be
            specified for scalar Tensors or ones that don't require grad.)
        retain_graph (bool, optional): If ``False``, the graph used to compute the grads will be
            reset after backward is complete. Defaults to ``False``. Note that in nearly all cases
            setting this option to ``True`` is not needed and often can be worked around in a much
            more efficient way. Defaults to the value of ``create_graph``.
        create_graph (bool, optional): If ``True``, graph of the derivative will be constructed,
            allowing to compute higher order derivative products. Defaults to ``False``.
    """
    backward_api(
        convert_to_tensor_tuple(tensors),
        convert_to_tensor_tuple(grad_tensors),
        retain_graph,
        create_graph,
    )