/*
* RapidMiner
*
* Copyright (C) 2001-2008 by Rapid-I and the contributors
*
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*
* 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
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*
* 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.functions;
/**
* Returns the value of the Epanechnikov kernel of both examples.
*
* @author Ingo Mierswa
* @version $Id: EpanechnikovKernel.java,v 1.4 2008/09/12 10:29:40 tobiasmalbrecht Exp $
*/
public class EpanechnikovKernel extends Kernel {
private static final long serialVersionUID = -4683350345234451645L;
/** The parameter sigma of the Epanechnikov kernel. */
private double sigma = 1.0d;
/** The parameter degree of the Epanechnikov kernel. */
private double degree = 1;
public int getType() {
return KERNEL_EPANECHNIKOV;
}
public void setSigma(double sigma) {
this.sigma = sigma;
}
public double getSigma() {
return sigma;
}
public double getDegree() {
return degree;
}
public void setDegree(double degree) {
this.degree = degree;
}
/** Calculates kernel value of vectors x and y. */
public double calculateDistance(double[] x1, double[] x2) {
double expression = norm2(x1, x2) / sigma;
if (expression > 1)
return 0.0d;
else {
double minus = 1.0d - expression;
return Math.pow(minus, degree);
}
}
}