public static float normInf(float[] x) {
        int n = x.length;

        float f = abs(x[0]);
        for (int i = 1; i < n; i++) {
            f = Math.max(f, abs(x[i]));
        }

        return f;
    }
@Test
    public void testNormInf_doubleArr() {
        System.out.println("normInf");
        double[] x = {-2.1968219, -0.9559913, -0.0431738, 1.0567679, 0.3853515};
        assertEquals(2.196822, MathEx.normInf(x), 1E-6);
    }