class SemiStandardDeviationCalculator extends Function1D<double[], Double> {

  @Override
  public Double evaluate(final double[] x) {
    Validate.notNull(x, "x");
    final double mean = MEAN.evaluate(x);
    final int n = x.length;
    return new PartialMomentCalculator(mean, _useDownSide).evaluate(x) * n / (n - 1);
  }

  public  SemiStandardDeviationCalculator();
  public  SemiStandardDeviationCalculator(final boolean useDownSide);

}