test_gradient.py 文件源码

def test_dxdx():

    # Tests that the gradient of a scalar with respect to itself is 1
    # I use an integer in this case because people keep changing this
    # gradient to be 0 on integers but according to our interpretation
    # of the gradient as defined in the Op contract, it should be 1.
    # If you feel the need to change this unit test you are probably
    # modifying the Op contract and should definitely get the approval
    # of multiple people on theano-dev.

    x = theano.tensor.iscalar()
    g = theano.tensor.grad(x, x)

    g = g.eval({x: 12})

    assert np.allclose(g, 1.)