test_elemwise.py 文件源码

def test_gt_grad():
    """A user test that failed.

    Something about it made Elemwise.grad return something that was
    too complicated for get_scalar_constant_value to recognize as being 0, so
    gradient.grad reported that it was not a valid gradient of an
    integer.

    """
    floatX = config.floatX
    T = theano.tensor

    input_ = T.vector(dtype=floatX)
    random_values = numpy.random.RandomState(1234).uniform(
                                                low=-1, high=1, size=(2, 2))
    W_values = numpy.asarray(random_values, dtype=floatX)
    W = theano.shared(value=W_values, name='weights')
    correct_score = T.dot(input_, W)
    wrong_input = T.vector(dtype=floatX)
    wrong_score = theano.clone(correct_score, {input_: wrong_input})
    # Hinge loss

    scores = T.ones_like(correct_score) - correct_score + wrong_score
    cost = (scores * (scores > 0)).sum()
    T.grad(cost, input_)