Binh2.java

//  Binh2.java
//
//  Author:
//       Antonio J. Nebro <antonio@lcc.uma.es>
//
//  Copyright (c) 2012 Antonio J. Nebro
//
//  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 jmetal.problems;

import jmetal.core.Problem;
import jmetal.core.Solution;
import jmetal.encodings.solutionType.BinaryRealSolutionType;
import jmetal.encodings.solutionType.RealSolutionType;
import jmetal.util.JMException;
import jmetal.util.wrapper.XReal;

/**
 * Class representing problem Binh2
 */
public class Binh2 extends Problem{
  /**
   * Constructor
   * Creates a default instance of the Binh2 problem
   * @param solutionType The solution type must "Real" or "BinaryReal".
   */
  public Binh2(String solutionType) {
    numberOfVariables_  = 2;
    numberOfObjectives_ = 2;
    numberOfConstraints_= 2;
    problemName_        = "Binh2";
        
    lowerLimit_ = new double[numberOfVariables_];
    upperLimit_ = new double[numberOfVariables_];        
    lowerLimit_[0] = 0.0;
    lowerLimit_[1] = 0.0;        
    upperLimit_[0] = 5.0;
    upperLimit_[1] = 3.0;
        
    if (solutionType.compareTo("BinaryReal") == 0)
      solutionType_ = new BinaryRealSolutionType(this) ;
    else if (solutionType.compareTo("Real") == 0)
    	solutionType_ = new RealSolutionType(this) ;
    else {
    	System.out.println("Error: solution type " + solutionType + " invalid") ;
    	System.exit(-1) ;
    }  
  } // ConstrEx
     
  /** 
  * Evaluates a solution 
  * @param solution The solution to evaluate
   * @throws JMException 
  */
  public void evaluate(Solution solution) throws JMException {
		XReal vars = new XReal(solution) ;
		
    double [] fx = new double[2] ; // function values     
    double [] x = new double[numberOfVariables_] ;
    for (int i = 0 ; i < numberOfVariables_; i++)
    	x[i] = vars.getValue(i) ;
    
    fx[0] = 4.0*x[0]*x[0] + 4*x[1]*x[1] ;        
    fx[1] = (x[0]-5.0)*(x[0]-5.0) + (x[1]-5.0)*(x[1]-5.0) ;        
    
    solution.setObjective(0,fx[0]);
    solution.setObjective(1,fx[1]);
  } // evaluate

 /** 
  * Evaluates the constraint overhead of a solution 
  * @param solution The solution
 * @throws JMException 
  */  
  public void evaluateConstraints(Solution solution) throws JMException {
    double [] constraint = new double[this.getNumberOfConstraints()];

    double x0 = solution.getDecisionVariables()[0].getValue();
    double x1 = solution.getDecisionVariables()[1].getValue();
        
    constraint[0] =  -1.0*(x0-5)*(x0-5) - x1*x1 + 25.0 ;
    constraint[1] =  (x0-8)*(x0-8) + (x1+3)*(x1+3) - 7.7 ;
        
    double total = 0.0;
    int number = 0;
    for (int i = 0; i < this.getNumberOfConstraints(); i++)
      if (constraint[i]<0.0){
        total+=constraint[i];
        number++;
      }
        
    solution.setOverallConstraintViolation(total);    
    solution.setNumberOfViolatedConstraint(number);         
  } // evaluateConstraints  
} // Binh2