function [x, y] = makeGrid(m, n) ln = linspace(-1, 1, n); st = linspace(-1, 1, m); xh = kron(ones(1, m), ln); yh = kron(st, ones(1, n)); xv = yh; yv = xh; x = [xh xv]; y = [yh yv]; x = reshape(x, n, 2*m); y = reshape(y, n, 2*m);