StatisticsUtilities { public static double sampleVariance(double[] xs) { return sumOfSquares(xs) / (xs.length - 1.0); }  static double percentile(final double[] values, final double p); static double median(double[] xs); static int argmax(double[] xs); static int argmax(int[] xs); @SuppressWarnings("unchecked") static int argmax(int[] xs, int rank); static int argmin(double[] xs); static int argmin(int[] xs); static int softmax(double[] ps, double temperature); static int probabilistic(double[] ps); static double[] distribution(double[] raw); static double[] distribution(int[] raw); static double mode(double[] xs); static double mode(double[] xs, double epsilon); static double maximum(double[] xs); static int maximum(Collection<Integer> xs); static long maximum(long[] xs); static double minimum(double[] xs); static double average(double[] xs); static int sum(int[] vals); static double sum(double[] vals); static int sum(Collection<Integer> xs); static double sumDouble(Collection<Double> xs); static double populationStandardDeviation(double[] xs); static double sampleStandardDeviation(double[] xs); static double populationVariance(double[] xs); static double sampleVariance(double[] xs); static double sumOfSquares(double[] xs); static double instantaneousErrorEnergy(double desired, double output); static double instantaneousTotalErrorEnergy(ArrayList<Pair<Double, Double>> pairs); static double averageSquaredErrorEnergy(ArrayList<ArrayList<Pair<Double, Double>>> samples); static double tValue(int runs);  }
@Test public void testSampleVariance() { double[] test1 = {1, 2, 3}; double[] test2 = {0, 10, 50}; double[] test3 = {2, 4, 6, 8}; assertEquals(StatisticsUtilities.sampleVariance(test1), 1, ERROR); assertEquals(StatisticsUtilities.sampleVariance(test2), 700, ERROR); assertEquals(StatisticsUtilities.sampleVariance(test3), 20.0 / 3.0, ERROR); }