Fonseca.java

//  Fonseca.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;

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

/** 
 * Class representing problem Fonseca
 */
public class Fonseca extends Problem {

	/** 
	 * Constructor
	 * Creates a default instance of the Fonseca problem
	 * @param solutionType The solution type must "Real", "BinaryReal, 
	 * ArrayReal, or ArrayRealC".
	 */
	public Fonseca(String solutionType) {
		numberOfVariables_   = 3;
		numberOfObjectives_  = 2;
		numberOfConstraints_ = 0;
		problemName_         = "Fonseca";

		upperLimit_ = new double[numberOfVariables_];
		lowerLimit_ = new double[numberOfVariables_];
		for (int var = 0; var < numberOfVariables_; var++){
			lowerLimit_[var] = -4.0;
			upperLimit_[var] = 4.0;
		} // for
    
    if (solutionType.compareTo("BinaryReal") == 0)
    	solutionType_ = new BinaryRealSolutionType(this) ;
    else if (solutionType.compareTo("Real") == 0)
    	solutionType_ = new RealSolutionType(this) ;
    else if (solutionType.compareTo("ArrayReal") == 0)
    	solutionType_ = new ArrayRealSolutionType(this) ;
    else {
    	System.out.println("Error: solution type " + solutionType + " invalid") ;
    	System.exit(-1) ;
    }
	} //Fonseca

	/** 
	 * Evaluates a solution 
	 * @param solution The solution to evaluate
	 * @throws JMException 
	 */        
	public void evaluate(Solution solution) throws JMException {
		XReal x = new XReal(solution) ;

		double [] f = new double[numberOfObjectives_];
		double sum1 = 0.0;
		for (int var = 0; var < numberOfVariables_; var++){
			sum1 += StrictMath.pow(x.getValue(var) 
					- (1.0/StrictMath.sqrt((double)numberOfVariables_)),2.0);            
		}
		double exp1 = StrictMath.exp((-1.0)*sum1);
		f[0] = 1 - exp1;

		double sum2 = 0.0;        
		for (int var = 0; var < numberOfVariables_; var++){
			sum2 += StrictMath.pow(x.getValue(var) 
					+ (1.0/StrictMath.sqrt((double)numberOfVariables_)),2.0);
		}    
		double exp2 = StrictMath.exp((-1.0)*sum2);
		f[1] = 1 - exp2;

		solution.setObjective(0,f[0]);
		solution.setObjective(1,f[1]);
	} // evaluate
} // Fonseca