@Test
  public void testSD_double_Array() {
    logger.info("\ntesting sd(double[] input)");
    double[] input = null;
    assertEquals(Double.NaN, MathUtil.sd(input), 0.0);
    assertEquals(Double.NaN, MathUtil.sd(new double[] {}), 0.0);
    assertEquals(Double.NaN, MathUtil.sd(new double[] {1.0}), 0.0);

    assertEquals(1.581139, MathUtil.sd(new double[] {1.0, 2.0, 3.0, 4.0, 5.0}), 0.0001);
  }
  @Test
  public void testSD_int_array() {
    logger.info("\ntesting sd(int[] input)");
    int[] input = null;
    assertEquals(Double.NaN, MathUtil.sd(input), 0.0);
    assertEquals(Double.NaN, MathUtil.sd(new int[] {}), 0.0);
    assertEquals(Double.NaN, MathUtil.sd(new int[] {1}), 0.0);

    assertEquals(1.581139, MathUtil.sd(new int[] {1, 2, 3, 4, 5}), 0.0001);
  }
  @Test
  public void testSD_List_Double() {
    logger.info("\ntesting sd(List<Double> input)");
    List<Double> input = null;
    assertEquals(Double.NaN, MathUtil.sd(input), 0.0);

    input = new ArrayList<Double>();
    assertEquals(Double.NaN, MathUtil.sd(input), 0.0);
    input.add(1.0);
    assertEquals(Double.NaN, MathUtil.sd(input), 0.0);
    input.add(2.0);
    input.add(3.0);
    input.add(4.0);
    input.add(5.0);
    assertEquals(1.581139, MathUtil.sd(input), 0.0001);
  }