expected_K = [2, -1, 0, 0, -1; -1, 2, -1, 0, 0; 0, -1, 2, -1, 0; 0, 0, -1, 2, -1; -1, 0, 0, -1, 2]; actual_K = diffusion_matrix_sparse(5); unit_test_equals("diffusion_matrix_sparse(5) looks right", ... true, ... isequal(actual_K, expected_K));