Why doesn't my simple pytorch network work on GPU device?

Question

I built a simple network from a tutorial and I got this error:

RuntimeError: Expected object of type torch.cuda.FloatTensor but found type torch.Flo

Answer 1

import torch
import numpy as np

x = torch.tensor(np.array(1), device='cuda:0')

print(x.device)  # Prints `cpu`

x = torch.tensor(1, device='cuda:0')

print(x.device)  # Prints `cuda:0`

Now the tensor resides on GPU

Answer 2

TL;DR
This is the fix

inputs = inputs.to(device)  

Why?!
There is a slight difference between torch.nn.Module.to() and torch.Tensor.to(): while Module.to() is an in-place operator, Tensor.to() is not. Therefore

net.to(device)

Changes net itself and moves it to device. On the other hand

inputs.to(device)

does not change inputs, but rather returns a copy of inputs that resides on device. To use that "on device" copy, you need to assign it into a variable, hence

inputs = inputs.to(device)