function.py 文件源码

def backward_gpu(self, inputs, grad_outputs):
        """Applies backprop to output gradient arrays on GPU.

        Args:
            inputs: Tuple of input :class:`cupy.ndarray`
                object(s).
            grad_outputs: Tuple of output gradient
                :class:`cupy.ndarray` object(s).

        Returns:
            tuple: Tuple of input gradient :class:`cupy.ndarray`
            object(s). Some or all of them can be ``None``, if the function is
            not differentiable on corresponding inputs.

        .. warning::

            Implementations of :class:`Function` must take care that the
            return value must be a tuple even if it returns only one array.

        """
        return tuple(None for _ in inputs)