poisson.java

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/**    
  * Copyright (C) 2006, Laboratorio di Valutazione delle Prestazioni - Politecnico di Milano

  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation; either version 2 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 General Public License for more details.

  * You should have received a copy of the GNU General Public License
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  */
  
package jmt.gui.common.distributions;

import jmt.gui.common.resources.ImageLoader;

import javax.swing.*;

/**
 * <p>Title: Poisson Distribution</p>
 * <p>Description: Poisson distribution data structure</p>
 * 
 * @author Bertoli Marco
 *         Date: 11-lug-2005
 *         Time: 15.27.13
 */
public class Poisson  extends Distribution{
    /**
     * Construct a new Poisson Distribution
     */
    public Poisson() {
        super("Poisson",
                "jmt.engine.random.Poisson",
                "jmt.engine.random.PoissonPar",
                "Poisson distribution");
        hasMean = true;
    }

    /**
     * Used to set parameters of this distribution.
     * @return distribution parameters
     */
    protected Parameter[] setParameters() {
        // Creates parameter array
        Parameter[] parameters = new Parameter[1];
        // Sets parameter lambda
        parameters[0] = new Parameter("mean",
                "\u03BB",
                Double.class,
                new Double(0.5));
        // Checks value of lambda must be greater than 0
        parameters[0].setValueChecker(new ValueChecker() {
            public boolean checkValue(Object value) {
                Double d = (Double) value;
                if (d.doubleValue() > 0)
                    return true;
                else
                    return false;
            }
        });

        return parameters;
    }

    /**
     * Sets explicative image of this distribution used, together with description, to help the
     * user to understand meaning of parameters.
     * @return explicative image
     */
    protected ImageIcon setImage() {
        return ImageLoader.loadImage("Poisson");
    }

    /**
     * Returns this distribution's short description
     * @return distribution's short description
     */
    public String toString() {
        return "poisson(" +
                FormatNumber(((Double)parameters[0].getValue()).doubleValue()) +
                ")";
    }

    /**
     * Sets the mean for this distribution
     * @param value mean value
     */
    public void setMean(double value) {
        // mean = lambda
        if (getParameter(0).setValue(new Double(value)))
            mean = value;
    }

    /**
     * This method is called whenever a parameter changes and <code>hasC</code> or
     * <code>hasMean</code> are true
     */
    public void updateCM() {
        mean = ((Double)getParameter(0).getValue()).doubleValue();
    }
}