/*
* 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.rvm.kernel;
/**
* Laplace kernel:
* K(x, y) = (lengthScale^{-2} * (x * y) + bias)^order
*
* @author Piotr Kasprzak
* @version $Id: KernelPoly.java,v 1.3 2008/05/09 19:23:26 ingomierswa Exp $
*/
public class KernelPoly extends KernelRadial {
private static final long serialVersionUID = -118526840262643388L;
/** Polynomial order */
protected double degree = 2;
/** Bias */
protected double bias = 0;
/** Constructor(s) */
public KernelPoly() {}
public KernelPoly(double lengthScale, double bias, double degree) {
super(lengthScale);
this.bias = bias;
this.degree = degree;
}
/** evaluate kernel */
public double eval(double[] x, double[] y) {
double result = 0;
for (int i = 0; i < x.length; i++) {
result += x[i] * y[i];
}
result = Math.pow(Math.pow(lengthScale, -2) * result + bias, degree);
return result;
}
public String toString() {
return "poly kernel [lengthScale = " + lengthScale + ", bias = " + bias + ", order = " + degree + "]";
}
}