/*
* 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;
/**
* Neural Kernel
*
* @author Stefan Rueping, Ingo Mierswa
* @version $Id: KernelNeural.java,v 1.3 2008/05/09 19:23:21 ingomierswa Exp $
*/
public class KernelNeural extends Kernel {
private static final long serialVersionUID = 3862702323530107467L;
double a = 1.0;
double b = 0.0;
/**
* Class constructor
*/
public KernelNeural() {};
/**
* Output as String
*/
public String toString() {
return ("neural(" + a + "," + b + ")");
};
public void setParameters(double a, double b) {
this.a = a;
this.b = b;
}
/**
* Calculates kernel value of vectors x and y
*/
public double calculate_K(int[] x_index, double[] x_att, int[] y_index, double[] y_att) {
// K = tanh(a(x*y)+b)
double prod = a * innerproduct(x_index, x_att, y_index, y_att) + b;
double e1 = Math.exp(prod);
double e2 = Math.exp(-prod);
return ((e1 - e2) / (e1 + e2));
};
};