org.um.feri.ears.problems.unconstrained.ProblemEasom.java Source code

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Here is the source code for org.um.feri.ears.problems.unconstrained.ProblemEasom.java

Source

package org.um.feri.ears.problems.unconstrained;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;

import org.apache.commons.lang3.ArrayUtils;
import org.um.feri.ears.problems.Problem;

/**
* Problem function!
* <p>
* 
* @author Matej Crepinsek
* @version 1
* 
*          <h3>License</h3>
* 
*          Copyright (c) 2011 by Matej Crepinsek. <br>
*          All rights reserved. <br>
* 
*          <p>
*          Redistribution and use in source and binary forms, with or without
*          modification, are permitted provided that the following conditions
*          are met:
*          <ul>
*          <li>Redistributions of source code must retain the above copyright
*          notice, this list of conditions and the following disclaimer.
*          <li>Redistributions in binary form must reproduce the above
*          copyright notice, this list of conditions and the following
*          disclaimer in the documentation and/or other materials provided with
*          the distribution.
*          <li>Neither the name of the copyright owners, their employers, nor
*          the names of its contributors may be used to endorse or promote
*          products derived from this software without specific prior written
*          permission.
*          </ul>
*          <p>
*          THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
*          "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
*          LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
*          FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
*          COPYRIGHT OWNERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
*          INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
*          BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
*          LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
*          CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
*          LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
*          ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
*          POSSIBILITY OF SUCH DAMAGE.
* 
*/
public class ProblemEasom extends Problem {

    public ProblemEasom() {
        super(2, 0);

        lowerLimit = new ArrayList<Double>(Collections.nCopies(numberOfDimensions, -100.0));
        upperLimit = new ArrayList<Double>(Collections.nCopies(numberOfDimensions, 100.0));

        name = "Easom";
    }

    //fEaso(x1,x2)=-cos(x1)cos(x2)exp(-((x1-pi)^2+(x2-pi)^2))
    public double eval(double x[]) {
        double v = -Math.cos(x[0]) * Math.cos(x[1])
                * Math.exp(-Math.pow((x[0] - Math.PI), 2) - Math.pow(x[1] - Math.PI, 2));
        return v;
    }

    @Override
    public double eval(Double[] ds) {
        return eval(ArrayUtils.toPrimitive(ds));
    }

    public double[][] getOptimalVector() {
        double[][] v = new double[1][numberOfDimensions];
        Arrays.fill(v[0], Math.PI);
        return v;
    }

    public double getOptimumEval() {
        return -1.;
    }

    @Override
    public boolean isFirstBetter(Double[] x, double eval_x, Double[] y, double eval_y) {
        return eval_x < eval_y;
    }
}