/*
* 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.generator;
/**
* The sinc function on R^n for n >= 1
*
* The Label is f(x) = sin(x) / ||x||, if ||x|| != 0, and 0 else.
*
* @author Piotr Kasprzak
* @version $Id: SincFunction.java,v 1.3 2008/05/09 19:22:50 ingomierswa Exp $
*/
public class SincFunction extends RegressionFunction {
/* L2 norm on R^n */
public double norm_l2(double[] vector) {
double result = 0;
for (int i = 0; i < vector.length; i++) {
result += vector[i] * vector[i];
}
return Math.sqrt(result);
}
public double calculate(double[] att) {
double norm = norm_l2(att);
double result;
if (norm <= Double.MIN_VALUE) {
// Treat as 0
result = 0;
} else {
result = Math.sin(norm) / norm;
}
return result;
}
}