How would you do this manually? Most likely, this would be the same method you'd use with a loop.
However, I do agree that if that's the exact wording of the assignment it's very poorly worded. For a start, 'loop the matrix' is not even proper english. Secondly, it doesn't explain what you should loop over, I assume you're expected to write a double for loop over the rows and columns, but you could also loop over the diagonals.
Of course, the proper way of doing this in matlab is without a loop, so the pedagogical aspect of that homework is questionable (in my opinion). Here's what I'd do:
for i = pi %pointless loop that only does one iteration. Only here because the assignment asks for a loop
A = toeplitz([2, -1, ones(1, 4)], [2, -1, ones(1, 2)]); %can be achieved many different ways in just one line
end
This is likely to get you a fail however even if it does produce the correct result.
