/* * Ackley.java * * Created on January 11, 2003, 2:09 PM * *  * Copyright (C) 2003 - Edwin S. Peer  * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 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 General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA  *    */package net.sourceforge.cilib.Functions;import net.sourceforge.cilib.Problem.*;import java.lang.*;/** * * @author  espeer */public class Ackley extends Function {        public static final int DEFAULT_DIMENSION = 30;    public static final Domain DEFAULT_DOMAIN = new Domain(-30, 30);        public Ackley() {        super(DEFAULT_DIMENSION, DEFAULT_DOMAIN, 0);    }        public double evaluate(double[] x) {        double sumsq = 0.0;        double sumcos = 0.0;        for (int i = 0; i < dimension; ++i) {            sumsq += x[i] * x[i];            sumcos += Math.cos(2 * Math.PI * x[i]);        }        return - 20.0 * Math.exp(-0.2 * Math.sqrt(sumsq / dimension))                - Math.exp(sumcos / dimension) + 20 + Math.E;    }}