2 unit_test_equals("eye(5) is upper-triangular", ...
4 is_upper_triangular(A));
9 unit_test_equals("An upper-triangular matrix is upper-triangular", ...
11 is_upper_triangular(A));
14 unit_test_equals("A lower-triangular matrix is not upper-triangular", ...
16 is_upper_triangular(A'));