/**
* 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.engine.random;
import jmt.common.exception.IncorrectDistributionParameterException;
/**
*
* This is the parameter that should be passed to the Pareto
* distribution.
*
* <br><br>Copyright (c) 2003
* <br>Politecnico di Milano - dipartimento di Elettronica e Informazione
* @author Fabrizio Frontera - ffrontera@yahoo.it
* @author Bertoli Marco 10-oct-2005
*
*/
public class ParetoPar extends AbstractParameter implements Parameter {
private double alpha;
private double k;
/**
* It creates a new pareto parameter according with the data provided by the user.
* The user provides the value of the parameter k and alpha of the new pareto
* distribution. These value are verified by the constructor.
*
* @param alpha double containing the alpha parameter of the distribution (must be greater than zero).
* @param k double containing the k parameter of the distribution (must be greater than zero).
*
* @throws IncorrectDistributionParameterException if k or alpha are not both greater than zero.
*
*/
public ParetoPar(double alpha, double k) throws IncorrectDistributionParameterException {
this.alpha = alpha;
this.k = k;
if (!check()) {
if (k <= 0) {
throw new IncorrectDistributionParameterException("k must be gtz");
}
if (alpha <= 0) {
throw new IncorrectDistributionParameterException("alpha must be gtz");
}
}
}
public ParetoPar(Double walpha, Double wk) throws IncorrectDistributionParameterException {
this(walpha.doubleValue(), wk.doubleValue());
}
/**
* It controls if the parameter is correct. For the pareto distribution, the
* parameter is right if both alpha and k are greater than zero.
*
* @return boolean, indicating wether the parameter is correct or not.
*
*/
@Override
public boolean check() {
if ((alpha <= 0) || (k <= 0)) {
return false;
} else {
return true;
}
}
/**
* It returns the value of the parameter alpha of the pareto distribution.
*
* @return double with the alpha parameter of the pareto distribution.
*
*/
public double getAlpha() {
return alpha;
}
/**
* It returns the value of the parameter k of the pareto distribution.
*
* @return double with the k parameter of the pareto distribution.
*
*/
public double getK() {
return k;
}
/**
* it change the alpha of the distribution.
* It allow the user to change the value of the parameter alpha of the pareto
* distribution. It verify that the provided value is correct (alpha must be
* greater than zero).
*
* @param alpha double indicating the new value of the parameter alpha
* @throws IncorrectDistributionParameterException if alpha is not greater than zero.
*
*/
public void setAlpha(double alpha) throws IncorrectDistributionParameterException {
if (alpha <= 0) {
throw new IncorrectDistributionParameterException("alpha must be gtz");
} else {
this.alpha = alpha;
}
}
/**
* it change the k of the distribution.
* It allow the user to change the value of the parameter k of the pareto
* distribution. It verify that the provided value is correct (k must be
* greater than zero).
*
* @param k double indicating the new value of the parameter k
* @throws IncorrectDistributionParameterException
*
*/
public void setK(double k) throws IncorrectDistributionParameterException {
if (k <= 0) {
throw new IncorrectDistributionParameterException("k must be gtz");
} else {
this.k = k;
}
}
/**
* Sets mean for a given distribution parameter. This method is required to adjust distributions
* mean values into Load Dependent Service Time Strategy
* @param meanValue new mean value for this distribution
* Author: Bertoli Marco
* @throws IncorrectDistributionParameterException if mean value is invalid for this distribution
*/
@Override
public void setMean(double meanValue) throws IncorrectDistributionParameterException {
if (meanValue <= 0 || Double.isInfinite(meanValue)) {
throw new IncorrectDistributionParameterException("Mean value must be finite and greater than zero");
}
k = meanValue * (alpha - 1) / alpha;
}
} // end ParetoPar