/*
* RapidMiner
*
* Copyright (C) 2001-2008 by Rapid-I and the contributors
*
* Complete list of developers available at our web site:
*
* http://rapid-i.com
*
* 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 com.rapidminer.operator.learner.functions.kernel.jmysvm.kernel;
/**
* Epanechnikov Kernel
*
* @author Ingo Mierswa
* @version $Id: KernelEpanechnikov.java,v 1.3 2008/05/09 19:23:21 ingomierswa Exp $
*/
public class KernelEpanechnikov extends Kernel {
private static final long serialVersionUID = -2375190740988942684L;
private double sigma = 1;
private double degree = 1;
/** Output as String */
public String toString() {
return ("epanechnikov(s=" + sigma + ",d=" + degree + ")");
};
/** Class constructor. */
public KernelEpanechnikov() {}
public void setParameters(double sigma, double degree) {
this.sigma = sigma;
this.degree = degree;
}
/** Calculates kernel value of vectors x and y. */
public double calculate_K(int[] x_index, double[] x_att, int[] y_index, double[] y_att) {
double expression = norm2(x_index, x_att, y_index, y_att) / sigma;
if (expression > 1)
return 0.0d;
else {
double minus = 1.0d - expression;
return Math.pow(minus, degree);
}
}
}