## Solved over the rationals.
expected = [2/73; 11/73; 26/73];
-actual = conjugate_gradient_method(A, b, x0, 1e-6);
+actual = conjugate_gradient_method(A, b, x0, 1e-6, 1000);
diff = norm(actual - expected);
unit_test_equals("CGM works on an example", ...