/** * Griewank.java * * @author Antonio J. Nebro * @version 1.0 */package jmetal.problems.singleObjective;import jmetal.base.DecisionVariables;import jmetal.base.Problem;import jmetal.base.Solution;import jmetal.base.Configuration.SolutionType_;import jmetal.base.Configuration.VariableType_;import jmetal.util.JMException;public class Griewank extends Problem {  /**    * Constructor   * Creates a default instance of the Griewank problem   * @param numberOfVariables Number of variables of the problem    * @param solutionType The solution type must "Real" or "BinaryReal".    */  public Griewank(Integer numberOfVariables, String solutionType) {    numberOfVariables_   = numberOfVariables;    numberOfObjectives_  = 1;    numberOfConstraints_ = 0;    problemName_         = "Sphere";            upperLimit_ = new double[numberOfVariables_];    lowerLimit_ = new double[numberOfVariables_];    for (int var = 0; var < numberOfVariables_; var++){      lowerLimit_[var] = -600.0;      upperLimit_[var] = 600.0;    } // for            solutionType_ = Enum.valueOf(SolutionType_.class, solutionType) ;         // All the variables are of the same type, so the solutionType name is the    // same than the variableType name    variableType_ = new VariableType_[numberOfVariables_];    for (int var = 0; var < numberOfVariables_; var++){      variableType_[var] = Enum.valueOf(VariableType_.class, solutionType) ;        } // for  } // Griewank      /**   * Evaluates a solution   * @param solution The solution to evaluate   * @throws JMException   */          public void evaluate(Solution solution) throws JMException {    DecisionVariables decisionVariables  = solution.getDecisionVariables();    double sum  = 0.0    ;    double mult = 0.0    ;    double d    = 4000.0 ;    for (int var = 0; var < numberOfVariables_; var++) {      sum += decisionVariables.variables_[var].getValue() *              decisionVariables.variables_[var].getValue() / d ;          mult *= Math.cos(decisionVariables.variables_[var].getValue()/Math.sqrt(var)) ;        }            solution.setObjective(0, 1.0 + sum - mult) ;  } // evaluate} // Griewank