//  DTLZ6.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 jmetal.problems.DTLZ;

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

/**
 * Class representing problem DTLZ6
 */
 public class DTLZ6 extends Problem{
  
 /**
  * Creates a default DTLZ6 problem instance (12 variables and 3 objectives)
  * @param solutionType The solution type must "Real" or "BinaryReal". 
  */
  public DTLZ6(String solutionType) throws ClassNotFoundException {
    this(solutionType, 12, 3);
  } // DTLZ6

 /**
  * Creates a new DTLZ6 problem instance
  * @param numberOfVariables Number of variables
  * @param numberOfObjectives Number of objective functions
  * @param solutionType The solution type must "Real" or "BinaryReal". 
  */
  public DTLZ6(String  solutionType,
               Integer numberOfVariables,
               Integer numberOfObjectives) {
    numberOfVariables_  = numberOfVariables;
    numberOfObjectives_ = numberOfObjectives;
    numberOfConstraints_= 0;
    problemName_        = "DTLZ6";
        
    lowerLimit_ = new double[numberOfVariables_];
    upperLimit_ = new double[numberOfVariables_];
    for (int var = 0; var < numberOfVariables_; var++){
      lowerLimit_[var] = 0.0;
      upperLimit_[var] = 1.0;
    } //for
        
    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) ;
    }            
  } // DTLZ6
    
  /** 
  * Evaluates a solution 
  * @param solution The solution to evaluate
   * @throws jmetal.util.JMException
  */      
  public void evaluate(Solution solution) throws JMException {
    Variable[] gen  = solution.getDecisionVariables();

    double [] x = new double[numberOfVariables_];
    double [] f = new double[numberOfObjectives_];
    double [] theta = new double[numberOfObjectives_-1];
    int k = numberOfVariables_ - numberOfObjectives_ + 1;
        
    for (int i = 0; i < numberOfVariables_; i++)
      x[i] = gen[i].getValue();
        
    double g = 0.0;
    for (int i = numberOfVariables_ - k; i < numberOfVariables_; i++)
      g += Math.pow(x[i],0.1);
        
    double t = Math.PI  / (4.0 * (1.0 + g));
    theta[0] = x[0] * Math.PI / 2;
    for (int i = 1; i < (numberOfObjectives_-1); i++) 
      theta[i] = t * (1.0 + 2.0 * g * x[i]);			
        
    for (int i = 0; i < numberOfObjectives_; i++)
      f[i] = 1.0 + g;
        
    for (int i = 0; i < numberOfObjectives_; i++){
      for (int j = 0; j < numberOfObjectives_ - (i + 1); j++)            
        f[i] *= Math.cos(theta[j]);
        if (i != 0){
          int aux = numberOfObjectives_ - (i + 1);
          f[i] *= Math.sin(theta[aux]);
        } //if
    } // for

    for (int i = 0; i < numberOfObjectives_; i++)
      solution.setObjective(i,f[i]);        
  } // evaluate
}

