sigmoid.py 文件源码

def backward_gpu(self, inputs, grads):
        x = inputs[0]
        gy = grads[0]
        if (cuda.cudnn_enabled and self.use_cudnn and
                (_cudnn_version >= 3000 or x.dtype != numpy.float16)):
            gx = cuda.cupy.cudnn.activation_backward(x, self.y, gy, _mode)
        else:
            gx = cuda.elementwise(
                'T y, T gy', 'T gx',
                'gx = gy * y * (1 - y)',
                'sigmoid_bwd')(self.y, gy)
        return gx,