001    /*

002     * JNI_SVM-light - A Java Native Interface for SVM-light

003     * 

004     * Copyright (C) 2005 

005     * Tom Crecelius & Martin Theobald 

006     * Max-Planck Institute for Computer Science

007     * 

008     * This program is free software; you can redistribute it and/or modify it under

009     * the terms of the GNU General Public License as published by the Free Software

010     * Foundation.

011     * 

012     * This program is distributed in the hope that it will be useful, but WITHOUT

013     * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS

014     * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more

015     * details.

016     * 

017     * You should have received a copy of the GNU General Public License along with

018     * this program; if not, write to the Free Software Foundation, Inc., 51

019     * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA

020     */

021    

022    package jnisvmlight;

023    

024    /**

025     * A polynomial kernel.

026     * 

027     * @author Tom Crecelius & Martin Theobald

028     */

029    public class PolynomialKernel extends ExtendedKernel {

030    

031      private double m_order;

032    

033      protected PolynomialKernel() {

034        this(new LinearKernel(), 3.0, 1.0, 1.0);

035      }

036    

037      public PolynomialKernel(Kernel nestedKernel, double order, double a, double c) {

038        super(nestedKernel, a, c);

039        this.m_order = order;

040      }

041    

042      public double evaluate(FeatureVector v1, FeatureVector v2) {

043        return Math.pow(m_a * m_kernel.evaluate(v1, v2) + m_c, m_order);

044      }

045    

046      public double getOrder() {

047        return m_order;

048      }

049    

050      public void setOrder(double order) {

051        this.m_order = order;

052      }

053    

054      public String toString() {

055        return "Polynomial kernel K(x, y | k) = (" + m_a + " * k(x, y) + " + m_c

056            + ")^" + m_order + ". k = " + m_kernel.toString();

057      }

058    }