jasima.core.random.continuous.DblNormal.java Source code

Introduction

Here is the source code for jasima.core.random.continuous.DblNormal.java

Source

/*******************************************************************************
 * This file is part of jasima, v1.3, the Java simulator for manufacturing and 
 * logistics.
 *  
 * Copyright (c) 2015       jasima solutions UG
 * Copyright (c) 2010-2015 Torsten Hildebrandt and jasima contributors
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *******************************************************************************/
package jasima.core.random.continuous;

import jasima.core.util.Pair;
import jasima.core.util.Util;

import org.apache.commons.math3.exception.NotPositiveException;
import org.apache.commons.math3.exception.NotStrictlyPositiveException;

/**
 * Creates a number stream with values following a <a
 * href="http://en.wikipedia.org/wiki/Normal_distribution">Normal
 * distribution</a>.
 * 
 * @author Torsten Hildebrandt
 * @version 
 *          "$Id$"
 * 
 * @see <a href="http://en.wikipedia.org/wiki/Normal_distribution">Normal
 *      distribution (Wikipedia)</a>
 * @see <a href="http://mathworld.wolfram.com/NormalDistribution.html">Normal
 *      distribution (MathWorld)</a>
 */
public class DblNormal extends DblStream {

    private static final long serialVersionUID = 8266321644360710699L;

    private double mean = 0.0;
    private double stdev = 1.0;

    public DblNormal() {
        super();
    }

    @Override
    public double nextDbl() {
        return getMean() + rndGen.nextGaussian() * getStdev();
    }

    @Override
    public double getNumericalMean() {
        return mean;
    }

    @Override
    public Pair<Double, Double> getValueRange() {
        return new Pair<>(Double.NEGATIVE_INFINITY, Double.POSITIVE_INFINITY);
    }

    @Override
    public String toString() {
        return String.format(Util.DEF_LOCALE, "DblNormal(mean=%f;stdev=%f)", getMean(), getStdev());
    }

    public double getMean() {
        return mean;
    }

    /**
     * Sets the mean value of this normally distributed number stream. Default
     * value is {@code 0.0}.
     * 
     * @param mean
     *            The mean value.
     */
    public void setMean(double mean) {
        this.mean = mean;
    }

    public double getStdev() {
        return stdev;
    }

    /**
     * Sets the standard deviation of this normally distributed number stream.
     * This defaults to {@code 1.0}.
     * 
     * @param stdev
     *            The standard deviation.
     * @throws NotPositiveException
     *             Raised if stdev was negative.
     */
    public void setStdev(double stdev) throws NotPositiveException {
        if (stdev >= 0.0) {
            this.stdev = stdev;
        } else {
            throw new NotStrictlyPositiveException(stdev);
        }
    }

}