de.termininistic.serein.examples.benchmarks.functions.multimodal.LevyFunction.java Source code

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Here is the source code for de.termininistic.serein.examples.benchmarks.functions.multimodal.LevyFunction.java

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/**
 * Copyright (C) 2015 Tobias Uhlig (tobias.uhlig@unibw.de)
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *         http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package de.termininistic.serein.examples.benchmarks.functions.multimodal;

import org.apache.commons.math3.linear.ArrayRealVector;
import org.apache.commons.math3.linear.RealVector;

import de.termininistic.serein.examples.benchmarks.functions.BenchmarkFunction;
import de.termininistic.serein.examples.benchmarks.functions.Domain;

public class LevyFunction implements BenchmarkFunction {

    public final static Domain DEFAULT_DOMAIN = new Domain(-10.0, 10.0);

    private final Domain domain;

    public LevyFunction() {
        this(DEFAULT_DOMAIN);
    }

    public LevyFunction(Domain domain) {
        this.domain = domain;
    }

    @Override
    public double map(RealVector v) {
        double[] x = v.toArray();
        double sum = Math.pow(Math.sin(Math.PI * w(x[0])), 2);
        for (int i = 0; i < x.length - 1; i++) {
            sum += Math.pow((w(x[i]) - 1), 2) * (1 + 10 * Math.pow(Math.sin(2 * Math.PI * w(x[0]) + 1), 2)
                    + Math.pow(w(x[x.length - 1]) - 1, 2)
                            * (1 + Math.pow(Math.sin(2 * Math.PI * w(x[x.length - 1]) + 1), 2)));
        }
        return sum;
    }

    private double w(double x) {
        return 1 + (x - 1) / 4;
    }

    @Override
    public Domain getDomain() {
        return domain;
    }

    @Override
    public RealVector getOptimum(int dimension) {
        return new ArrayRealVector(dimension, 1.0);
    }

    public static void main(String[] args) {
        LevyFunction levy = new LevyFunction();
        System.out.println(levy.map(levy.getOptimum(5)));
    }

}