I agree, but the last part (assuming you meant to write in Python), could be written as: sum(f(x,y) for x in X for y in Y) ...which, ironically, is syntax i

I agree, but the last part (assuming you meant to write in Python), could be written as: sum(f(x,y) for x in X for y in Y) ...which, ironically, is syntax inspired by mathematical notation :)