Example usage for org.apache.commons.math3.distribution GammaDistribution GammaDistribution

Introduction

In this page you can find the example usage for org.apache.commons.math3.distribution GammaDistribution GammaDistribution.

Prototype

public GammaDistribution(double shape, double scale, double inverseCumAccuracy)
        throws NotStrictlyPositiveException 

Source Link

Document

Creates a new gamma distribution with specified values of the shape and scale parameters.

Usage

From source file:math.test.TestDimpleRandom.java

/**
 * Measures speed of Apache vs Colt generators
 *///from w w  w.j a  va 2 s. c om
public static void main(String[] args) {
    RandomGenerator apacheGenerator = new MersenneTwister(42);
    cern.jet.random.engine.RandomEngine cernGenerator = new cern.jet.random.engine.MersenneTwister();

    final int N = 100000;
    long start, end;

    start = System.nanoTime();
    for (int i = N; --i >= 0;) {
        apacheGenerator.nextDouble();
    }
    end = System.nanoTime();
    long apacheTime = end - start;

    start = System.nanoTime();
    for (int i = N; --i >= 0;) {
        cernGenerator.nextDouble();
    }
    end = System.nanoTime();

    long cernTime = end - start;

    System.out.format("MersenneTwister.nextDouble() x %d apache/cern %f\n", N, (double) apacheTime / cernTime);

    start = System.nanoTime();
    for (int i = N; --i >= 0;) {
        BetaDistribution apacheBeta = new BetaDistribution(apacheGenerator, 1.0, 1.0);
        apacheBeta.sample();
    }
    end = System.nanoTime();
    apacheTime = end - start;

    cern.jet.random.Beta cernBeta = new cern.jet.random.Beta(1, 1, cernGenerator);

    start = System.nanoTime();
    for (int i = N; --i >= 0;) {
        cernBeta.nextDouble();
    }
    end = System.nanoTime();
    apacheTime = end - start;

    System.out.format("Beta x %d apache/cern %f\n", N, (double) apacheTime / cernTime);

    start = System.nanoTime();
    for (int i = N; --i >= 0;) {
        GammaDistribution apacheGamma = new GammaDistribution(apacheGenerator, 1.0, 1.0);
        apacheGamma.sample();
    }
    end = System.nanoTime();
    apacheTime = end - start;

    cern.jet.random.Gamma cernGamma = new cern.jet.random.Gamma(1, 1, cernGenerator);

    start = System.nanoTime();
    for (int i = N; --i >= 0;) {
        cernGamma.nextDouble();
    }
    end = System.nanoTime();
    apacheTime = end - start;

    System.out.format("Gamma x %d apache/cern %f\n", N, (double) apacheTime / cernTime);

    start = System.nanoTime();
    for (int i = N; --i >= 0;) {
        BinomialDistribution apacheBinomial = new BinomialDistribution(apacheGenerator, 1, .5);
        apacheBinomial.sample();
    }
    end = System.nanoTime();
    apacheTime = end - start;

    cern.jet.random.Binomial cernBinomial = new cern.jet.random.Binomial(1, .5, cernGenerator);

    start = System.nanoTime();
    for (int i = N; --i >= 0;) {
        cernBinomial.nextInt();
    }
    end = System.nanoTime();
    apacheTime = end - start;

    System.out.format("Binomial x %d apache/cern %f\n", N, (double) apacheTime / cernTime);
}

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From source file:adams.data.distribution.Gamma.java

/**
 * Returns the configured distribution.//ww  w .j a  va  2  s  . com
 *
 * @return      the distribution
 */
@Override
public RealDistribution getRealDistribution() {
    return new GammaDistribution(m_Shape, m_Scale, m_InverseCumAccuracy);
}

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From source file:edu.cmu.tetrad.util.RandomUtil.java

/**
 * Returns the next random number drawn from the Gamma distribution with the given alpha and lambda.
 *
 * @param shape The shape parameter./*  w  ww.j  a  va  2s. c o m*/
 * @param scale The scale parameter.
 * @return Ibid.
 */
public double nextGamma(double shape, double scale) {
    return new GammaDistribution(randomGenerator, shape, scale).sample();
}

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From source file:io.coala.random.impl.RandomDistributionFactoryImpl.java

@Override
public RandomNumberDistribution<Double> getGamma(final RandomNumberStream rng, final Number shape,
        final Number scale) {
    final RealDistribution dist = new GammaDistribution(RandomNumberStream.Util.asCommonsRandomGenerator(rng),
            shape.doubleValue(), scale.doubleValue());
    return new RandomNumberDistribution<Double>() {
        @Override//  w  w  w .  j a va 2  s.  com
        public Double draw() {
            return dist.sample();
        }
    };
}

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