Solved by Nikronic in post #2 
              
              
                Hi, 
torch.cat() is a function to concatenate tensors on a specified channel. 
F.relu() is a activation function which you can use on any tensor to get the corresponding values. 
Here is an example: 

a = torch.randn(3, 2, 1, 1)
b = torch.randn(3, 2, 1, 1)
b = -1*b
ab = torch.cat((a, b), dim=1)
prin…