Solved by albanD in post #2 
              
              
                If you create an empty tensor, then give it as out=, then it will be resized and filled with the result. This will be the same as c = a + 3 in your first example. 
Doing c[:] = a + 3 will create an intermediary result and copy it into c (which will work only if c has been resized beforehand). 
If ca…