A = [4,3]~; H = [3,1; 0,2];
matmodhnf(A, H)
R = matmodhnf(A, H, &Q); [Q,R]

matmodhnf([4, 3], H)
matmodhnf(A, [3,2])
R = matmodhnf([4, 3], H, &Q); [Q,R]

B = [5,6; 1,2];
matmodhnf(B, H)
R = matmodhnf(B, H, &Q); [Q,R]
