normal.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: Normal Distribution</p>
 * <p>Description: Normal distribution data structure</p>
 * 
 * @author Bertoli Marco
 *         Date: 7-lug-2005
 *         Time: 17.46.19
 */
public class Normal extends Distribution {
    /**
     * Construct a new Normal Distribution
     */
    public Normal() {
        super("Normal",
                "jmt.engine.random.Normal",
                "jmt.engine.random.NormalPar",
                "Normal distribution");
        hasMean = true;
        hasC = true;
    }

    /**
     * Used to set parameters of this distribution.
     * @return distribution parameters
     */
    protected Distribution.Parameter[] setParameters() {
        // Creates parameter array
        Distribution.Parameter[] parameters = new Distribution.Parameter[2];
        // Sets parameter mean
        parameters[0] = new Distribution.Parameter("mean",
                "\u03BC",
                Double.class,
                new Double(2));
        // Checks value of mean must be equal greater then 0
        parameters[0].setValueChecker(new Distribution.ValueChecker() {
            public boolean checkValue(Object value) {
                Double d = (Double) value;
                if (d.doubleValue() >= 0)
                    return true;
                else
                    return false;
            }
        });

        // Sets parameter standardDeviation
        parameters[1] = new Distribution.Parameter("standardDeviation",
                "\u03C3",
                Double.class,
                new Double(1));
        // Checks value of standardDeviation must be greater then 0
        parameters[1].setValueChecker(new Distribution.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("Normal");
    }

    /**
     * Returns this distribution's short description
     * @return distribution's short description
     */
    public String toString() {
        return "norm(" +
                FormatNumber(((Double)parameters[0].getValue()).doubleValue()) +
                "; "+
                FormatNumber(((Double)parameters[1].getValue()).doubleValue()) +
                ")";
    }

    /**
     * Sets the mean for this distribution
     * @param value mean value
     */
    public void setMean(double value) {
        setCM(value, c);
    }

    /**
     * Sets the variation coefficient C for this distribution
     * @param value variation coefficient C value
     */
    public void setC (double value) {
        setCM(mean, value);
    }

    /**
     * Sets Mean and C values
     * @param mean mean value
     * @param c c value
     */
    protected void setCM(double mean, double c) {
        // sigma = c^2*mean^2
        // Backups old parameters to restore them upon a false result
        Object oldm = getParameter("mean").getValue();
        Object olds = getParameter("standardDeviation").getValue();
        if (getParameter("mean").setValue(new Double(mean)) &&
                getParameter("standardDeviation").setValue(new Double(c*c*mean*mean))) {
            this.mean = mean;
            this.c = c;
        }
        else {
            getParameter("mean").setValue(oldm);
            getParameter("standardDeviation").setValue(olds);
        }
    }

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