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CloudSim Plus: A modern, highly extensible and easier-to-use Java 8 Framework for Modeling and Simulation of Cloud Computing Infrastructures and Services

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package org.cloudbus.cloudsim.distributions;

import org.apache.commons.math3.distribution.NormalDistribution;
import org.apache.commons.math3.random.JDKRandomGenerator;
import org.apache.commons.math3.random.RandomGenerator;

/**
 * A Pseudo-Random Number Generator following the
 * Normal (Gaussian) distribution.
 *
 * @author Manoel Campos da Silva Filho
 */
public class NormalDistr extends NormalDistribution implements ContinuousDistribution{
    private long seed;

    /**
     * Creates a Normal (Gaussian) Pseudo-Random Number Generator (RNG) using the current time as seed.
     *
     * Internally, it relies on the {@link JDKRandomGenerator},
     * a wrapper for the {@link java.util.Random} class
     * that doesn't have high-quality randomness properties
     * but is very fast.
     *
     * @param mean the mean for the distribution.
     * @param standardDeviation the standard deviation for the distribution.
     *
     * @see #NormalDistr(double, double, long, RandomGenerator)
     */
    public NormalDistr(final double mean, final double standardDeviation) {
        this(mean, standardDeviation, ContinuousDistribution.defaultSeed());
    }

    /**
     * Creates a Normal (Gaussian) Pseudo-Random Number Generator (RNG).
     *
     * Internally, it relies on the {@link JDKRandomGenerator},
     * a wrapper for the {@link java.util.Random} class
     * that doesn't have high-quality randomness properties
     * but is very fast.
     *
	 * @param mean the mean for the distribution.
     * @param standardDeviation the standard deviation for the distribution.
     * @param seed the seed to be used.
     *
     * @see #NormalDistr(double, double, long, RandomGenerator)
     */
	public NormalDistr(final double mean, final double standardDeviation, final long seed) {
		this(mean, standardDeviation, seed, ContinuousDistribution.newDefaultGen(seed));
	}

    /**
     * Creates a Normal (Gaussian) Pseudo-Random Number Generator (RNG).
     * @param mean the mean for the distribution.
     * @param standardDeviation the standard deviation for the distribution.
     * @param seed the seed already used to initialize the Pseudo-Random Number Generator
     * @param rng the actual Pseudo-Random Number Generator that will be the base
*                 to generate random numbers following a continuous distribution.
     */
    public NormalDistr(final double mean, final double standardDeviation, final long seed, final RandomGenerator rng) {
        super(rng, mean, standardDeviation);
        if(seed < 0){
            throw new IllegalArgumentException("Seed cannot be negative");
        }
        this.seed = seed;
    }

    @Override
    public long getSeed() {
        return seed;
    }

    @Override
    public void reseedRandomGenerator(final long seed) {
        super.reseedRandomGenerator(seed);
        this.seed = seed;
    }
}