prelu.py 文件源码

def backward_gpu(self, inputs, grad_outputs):
        x, W = inputs
        gy = grad_outputs[0]
        masked = cuda.elementwise(
            'T x, T gy', 'T masked',
            'masked = x >= 0 ? (T)0 : (T)(x * gy)',
            'prelu_masked')(x, gy)
        axes = (0,) + tuple(six.moves.range(1 + W.ndim, gy.ndim))
        gW = masked.sum(axis=axes)

        gx = masked  # reuse buffer
        shape = _get_extended_shape(W, gx)
        _fwd_kern()(gy, x, W.reshape(shape), gx)
        return gx, gW