Pythorch教程中有错误吗?

官方pytorch教程( https://pytorch.org/tutorials/beginner/blitz/autograd_tutorial.html#gradients out.backward() 和 out.backward(torch.tensor(1)) 相当于。但事实似乎并非如此。

import torch

x = torch.ones(2, 2, requires_grad=True)
y = x + 2
z = y * y * 3
out = z.mean()

# option 1    
out.backward()

# option 2. Replace! do not leave one after the other
# out.backward(torch.tensor(1))

print(x.grad)

注意 :不要留下两个反向呼叫。将选项1替换为2。

更新 如果我用 正如教程所说,我得到:

E       RuntimeError: invalid gradient at index 0 - expected type torch.FloatTensor but got torch.LongTensor

../../../anaconda3/envs/phd/lib/python3.6/site-packages/torch/autograd/__init__.py:90: RuntimeError

我也试过用 out.backward(torch.Tensor(1)) 我得到的是:

E       RuntimeError: invalid gradient at index 0 - expected shape [] but got [1]

../../../anaconda3/envs/phd/lib/python3.6/site-packages/torch/autograd/__init__.py:90: RuntimeError