INNER CODE UNIT · Python

backward_pass

HIPS/autograd · autograd/core.py:26

def backward_pass(g, end_node):
    outgrads = {end_node: (g, False)}
    for node in toposort(end_node):
        outgrad = outgrads.pop(node)
        ingrads = node.vjp(outgrad[0])
        for parent, ingrad in zip(node.parents, ingrads):
            outgrads[parent] = add_outgrads(outgrads.get(parent), ingrad)
    return outgrad[0]


class VJPNode(Node):
    __slots__ = ["parents", "vjp"]

    def __init__(self, value, fun, args, kwargs, parent_argnums, parents):
        self.parents = parents
        try:
            vjpmaker = primitive_vjps[fun]
        except KeyError:

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