public static int max(int a, int b, int c) {
        return Math.max(Math.max(a, b), c);
    }
@Test
    public void testMax_doubleArr() {
        System.out.println("max");
        double[] x = {-2.1968219, -0.9559913, -0.0431738, 1.0567679, 0.3853515};
        assertEquals(1.0567679, MathEx.max(x), 1E-7);
    }