test_autograd.py 文件源码

def test_volatile(self):
        x = Variable(torch.ones(5, 5), requires_grad=True)
        y = Variable(torch.ones(5, 5) * 4, volatile=True)

        z = x ** 2
        self.assertFalse(z.volatile)
        self.assertTrue(z.requires_grad)
        self.assertIsNotNone(z.grad_fn)
        z.backward(torch.ones(5, 5))
        self.assertEqual(x.grad.data, torch.ones(5, 5) * 2)

        w = z + y
        self.assertTrue(w.volatile)
        self.assertFalse(w.requires_grad)
        self.assertRaises(RuntimeError, lambda: w.backward(torch.ones(5, 5)))
        self.assertIsNone(w.grad_fn)