net.sourceforge.cilib.functions.continuous.moo.zdt.ZDT2 Maven / Gradle / Ivy

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 *    _____ _/ /_/ /_    Computational Intelligence Library (CIlib)
 *   / ___/ / / / __ \   (c) CIRG @ UP
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package net.sourceforge.cilib.functions.continuous.moo.zdt;

import net.sourceforge.cilib.functions.ContinuousFunction;
import net.sourceforge.cilib.problem.FunctionOptimisationProblem;
import net.sourceforge.cilib.problem.MOOptimisationProblem;
import net.sourceforge.cilib.type.types.container.Vector;

/**
 * Zitzler-Thiele-Deb Test Function 2
 *
 * Characteristics:
 * 
 * Nonconvex Pareto-optimal front.
 * 
 *
 * 
 * This function is representative of the nonconvex counterpart to T1.
 * The Pareto-optimal front is formed with g(x) = 1
 * 
 *
 * 
 * References:
 * 
 * 
 * 

 * 
 * E. Zitzler, K. Deb and L. Thiele, "Comparison of multiobjective
 * evolutionary algorithms: Empirical results", in Evolutionary Computation,
 * vol 8, no 2, pp. 173-195, 2000.
 * 
 * 
 * 
 *
 */
public final class ZDT2 extends MOOptimisationProblem {

    private static final long serialVersionUID = -2949170760033824427L;
    private static final String DOMAIN = "R(0:1)^30";

    private static class ZDT2_h extends ContinuousFunction {

        private static final long serialVersionUID = 6575398958907399233L;
        private final ZDT_f1 f1;
        private final ZDT_g g;

        public ZDT2_h() {
            this.f1 = new ZDT_f1();
            this.g = new ZDT_g();
        }

        @Override
        public Double f(Vector input) {
            return 1.0 - (this.f1.f(input) / this.g.f(input)) * (this.f1.f(input) / this.g.f(input));
        }
    }

    private static class ZDT2_f2 extends ContinuousFunction {

        private static final long serialVersionUID = 1983853514735870004L;
        private final ZDT_g g;
        private final ZDT2_h h;

        public ZDT2_f2() {
            this.g = new ZDT_g();
            this.h = new ZDT2_h();
        }

        @Override
        public Double f(Vector input) {
            return this.g.f(input) * this.h.f(input);
        }
    }

    public ZDT2() {
        FunctionOptimisationProblem zdt2_f1 = new FunctionOptimisationProblem();
        zdt2_f1.setFunction(new ZDT_f1());
        zdt2_f1.setDomain(DOMAIN);
        add(zdt2_f1);

        FunctionOptimisationProblem zdt2_f2 = new FunctionOptimisationProblem();
        zdt2_f2.setFunction(new ZDT2_f2());
        zdt2_f2.setDomain(DOMAIN);
        add(zdt2_f2);
    }

    public ZDT2(ZDT2 copy) {
        super(copy);
    }

    @Override
    public ZDT2 getClone() {
        return new ZDT2(this);
    }
}