Example usage for org.apache.commons.math.stat.descriptive.moment StandardDeviation setBiasCorrected

Introduction

In this page you can find the example usage for org.apache.commons.math.stat.descriptive.moment StandardDeviation setBiasCorrected.

Prototype

public void setBiasCorrected(boolean isBiasCorrected) 

Source Link

Usage

From source file:com.test.zmisc.App.java

public static void main(String[] args) {
    double[] a = new double[32768];
    double[] b = new double[32768];

    ThreadLocalRandom rand = ThreadLocalRandom.current();

    for (int i = 0; i < a.length; i++) {
        a[i] = rand.nextDouble();//ww  w . j a  v a  2 s  .  c  om
        b[i] = a[i];
    }

    long ts = System.currentTimeMillis();
    PearsonsCorrelation corr = new PearsonsCorrelation();
    corr.correlation(a, b);
    ts = System.currentTimeMillis() - ts;
    System.out.println("Time elapsed:" + ts + "ms");

    // standard deviation is the sqrt(mean((X-avg)^2))

    ts = System.currentTimeMillis();
    double amean = average(a);
    double aStdDev = standardDeviation(a, amean);

    StandardDeviation sd = new StandardDeviation();
    sd.setBiasCorrected(false);

    double bmean = average(b);
    double bStdDev = standardDeviation(b, bmean);

    double cor = (covariance(a, aStdDev, b, bmean)) / (aStdDev * bStdDev);
    ts = System.currentTimeMillis() - ts;
    System.out.println("Time elapsed:" + ts + "ms");
}

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