Java tutorial
/** * Copyright (C) 2009 - present by OpenGamma Inc. and the OpenGamma group of companies * * Please see distribution for license. */ package com.opengamma.analytics.math.statistics.descriptive; import org.apache.commons.lang.Validate; import com.opengamma.analytics.math.function.Function1D; /** * Calculates the sample standard deviation of a series of data. The sample standard deviation of a series of data is defined as the square root of * the sample variance (see {@link SampleVarianceCalculator}). */ public class SampleStandardDeviationCalculator extends Function1D<double[], Double> { private static final Function1D<double[], Double> VARIANCE = new SampleVarianceCalculator(); /** * @param x The array of data, not null, must contain at least two data points * @return The sample standard deviation */ @Override public Double evaluate(final double[] x) { Validate.notNull(x, "x"); Validate.isTrue(x.length >= 2, "Need at least two points to calculate standard deviation"); return Math.sqrt(VARIANCE.evaluate(x)); } }