basic.py 文件源码

def grad(self, inputs, g):

        # g[1:] is all integers, so their Jacobian in this op
        # is 0. We thus don't need to worry about what their values
        # are.

        # if g[0] is disconnected, then this op doesn't contribute
        # any gradient anywhere. but we know that at least one of
        # g[1:] is connected, or this grad method wouldn't have been
        # called, so we should report zeros
        (csm,) = inputs
        if isinstance(g[0].type, DisconnectedType):
            return [csm.zeros_like()]

        data, indices, indptr, shape = csm_properties(csm)
        return [CSM(csm.format)(g[0], indices, indptr, shape)]

# don't make this a function or it breaks some optimizations below