Kursawe.java

//  Kursawe.java
//
//  Author:
//       Antonio J. Nebro <antonio@lcc.uma.es>
//       Juan J. Durillo <durillo@lcc.uma.es>
//
//  Copyright (c) 2011 Antonio J. Nebro, Juan J. Durillo
//
//  This program is free software: you can redistribute it and/or modify
//  it under the terms of the GNU Lesser 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 Lesser General Public License for more details.
// 
//  You should have received a copy of the GNU Lesser General Public License
//  along with this program.  If not, see <http://www.gnu.org/licenses/>.

package org.uma.jmetal.problem.multiobjective;

import org.uma.jmetal.problem.impl.AbstractDoubleProblem;
import org.uma.jmetal.solution.DoubleSolution;

import java.util.ArrayList;
import java.util.List;

/**
 * Class representing problem Kursawe
 */
@SuppressWarnings("serial")
public class Kursawe extends AbstractDoubleProblem {

  /**
   * Constructor.
   * Creates a default instance of the Kursawe problem.
   */
  public Kursawe() {
    // 3 variables by default
    this(3);
  }

  /**
   * Constructor.
   * Creates a new instance of the Kursawe problem.
   *
   * @param numberOfVariables Number of variables of the problem
   */
  public Kursawe(Integer numberOfVariables) {
    setNumberOfVariables(numberOfVariables);
    setNumberOfObjectives(2);
    setName("Kursawe");

    List<Double> lowerLimit = new ArrayList<>(getNumberOfVariables()) ;
    List<Double> upperLimit = new ArrayList<>(getNumberOfVariables()) ;

    for (int i = 0; i < getNumberOfVariables(); i++) {
      lowerLimit.add(-5.0);
      upperLimit.add(5.0);
    }

    setLowerLimit(lowerLimit);
    setUpperLimit(upperLimit);
  }

  /** Evaluate() method */
  public void evaluate(DoubleSolution solution){
    double aux, xi, xj;
    double[] fx = new double[getNumberOfObjectives()];
    double[] x = new double[getNumberOfVariables()];
    for (int i = 0; i < solution.getNumberOfVariables(); i++) {
      x[i] = solution.getVariableValue(i) ;
    }

    fx[0] = 0.0;
    for (int var = 0; var < solution.getNumberOfVariables() - 1; var++) {
      xi = x[var] * x[var];
      xj = x[var + 1] * x[var + 1];
      aux = (-0.2) * Math.sqrt(xi + xj);
      fx[0] += (-10.0) * Math.exp(aux);
    }

    fx[1] = 0.0;

    for (int var = 0; var < solution.getNumberOfVariables(); var++) {
      fx[1] += Math.pow(Math.abs(x[var]), 0.8) +
        5.0 * Math.sin(Math.pow(x[var], 3.0));
    }

    solution.setObjective(0, fx[0]);
    solution.setObjective(1, fx[1]);
  }
}