Tanaka.java

//  Tanaka.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.ConstrainedProblem;
import org.uma.jmetal.problem.impl.AbstractDoubleProblem;
import org.uma.jmetal.solution.DoubleSolution;
import org.uma.jmetal.util.solutionattribute.impl.NumberOfViolatedConstraints;
import org.uma.jmetal.util.solutionattribute.impl.OverallConstraintViolation;

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

/**
 * Class representing problem Tanaka
 */
@SuppressWarnings("serial")
public class Tanaka extends AbstractDoubleProblem implements ConstrainedProblem<DoubleSolution> {
  public OverallConstraintViolation<DoubleSolution> overallConstraintViolationDegree ;
  public NumberOfViolatedConstraints<DoubleSolution> numberOfViolatedConstraints ;

  /**
   * Constructor.
   * Creates a default instance of the problem Tanaka
   */
  public Tanaka() {
    setNumberOfVariables(2);
    setNumberOfObjectives(2);
    setNumberOfConstraints(2);
    setName("Tanaka") ;

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

    for (int i = 0; i < getNumberOfVariables(); i++) {
      lowerLimit.add(10e-5);
      upperLimit.add(Math.PI);
    }

    setLowerLimit(lowerLimit);
    setUpperLimit(upperLimit);

    overallConstraintViolationDegree = new OverallConstraintViolation<DoubleSolution>() ;
    numberOfViolatedConstraints = new NumberOfViolatedConstraints<DoubleSolution>() ;
  }

  @Override
  public void evaluate(DoubleSolution solution)  {
    solution.setObjective(0, solution.getVariableValue(0));
    solution.setObjective(1, solution.getVariableValue(1));
  }

  /** EvaluateConstraints() method */
  @Override
  public void evaluateConstraints(DoubleSolution solution)  {
    double[] constraint = new double[this.getNumberOfConstraints()];

    double x1 = solution.getVariableValue(0) ;
    double x2 = solution.getVariableValue(1) ;

    constraint[0] = (x1 * x1 + x2 * x2 - 1.0 - 0.1 * Math.cos(16.0 * Math.atan(x1 / x2)));
    constraint[1] = -2.0 * ((x1 - 0.5) * (x1 - 0.5) + (x2 - 0.5) * (x2 - 0.5) - 0.5);

    double overallConstraintViolation = 0.0;
    int violatedConstraints = 0;
    for (int i = 0; i < getNumberOfConstraints(); i++) {
      if (constraint[i]<0.0){
        overallConstraintViolation+=constraint[i];
        violatedConstraints++;
      }
    }

    overallConstraintViolationDegree.setAttribute(solution, overallConstraintViolation);
    numberOfViolatedConstraints.setAttribute(solution, violatedConstraints);
  }
}