A = [1,0;0,1]; unit_test_equals("The identity is positive definite", ... true, ... is_positive_definite(A)); A = [1,1;1,1]; unit_test_equals("All-ones matrix is not positive definite", ... false, ... is_positive_definite(A)); A = [5,1,2;1,6,3;2,3,7]; unit_test_equals("A diagonally-dominant matrix is positive definite", ... true, ... is_positive_definite(A));