/**
* Evaluates a solution.
*
* @param solution The solution to evaluate.
* @throws JMException
*/
public void evaluate(Solution solution) throws JMException {
Variable[] decisionVariables = solution.getDecisionVariables();
double[] x = new double[numberOfVariables_];
for (int i = 0; i < numberOfVariables_; i++) x[i] = decisionVariables[i].getValue();
int count1, count2;
double prod1, prod2;
double sum1, sum2, yj, hj, pj;
sum1 = sum2 = 0.0;
count1 = count2 = 0;
prod1 = prod2 = 1.0;
for (int j = 2; j <= numberOfVariables_; j++) {
yj = x[j - 1] - Math.sin(6.0 * Math.PI * x[0] + j * Math.PI / numberOfVariables_);
pj = Math.cos(20.0 * yj * Math.PI / Math.sqrt(j));
if (j % 2 == 0) {
sum2 += yj * yj;
prod2 *= pj;
count2++;
} else {
sum1 += yj * yj;
prod1 *= pj;
count1++;
}
}
hj = 2.0 * (0.5 / N_ + epsilon_) * Math.sin(2.0 * N_ * Math.PI * x[0]);
if (hj < 0.0) hj = 0.0;
solution.setObjective(0, x[0] + hj + 2.0 * (4.0 * sum1 - 2.0 * prod1 + 2.0) / (double) count1);
solution.setObjective(
1, 1.0 - x[0] + hj + 2.0 * (4.0 * sum2 - 2.0 * prod2 + 2.0) / (double) count2);
} // evaluate
// constriction coefficient (M. Clerc)
private double constrictionCoefficient(double c1, double c2) {
double rho = c1 + c2;
// rho = 1.0 ;
if (rho <= 4) {
return 1.0;
} else {
return 2 / (2 - rho - Math.sqrt(Math.pow(rho, 2.0) - 4.0 * rho));
}
} // constrictionCoefficient
/**
* Returns the distance between two solutions in objective space.
*
* @param solutionI The first <code>Solution</code>.
* @param solutionJ The second <code>Solution</code>.
* @return the distance between solutions in objective space.
*/
public double distanceBetweenObjectives(Solution solutionI, Solution solutionJ) {
double diff; // Auxiliar var
double distance = 0.0;
// -> Calculate the euclidean distance
for (int nObj = 0; nObj < solutionI.numberOfObjectives(); nObj++) {
diff = solutionI.getObjective(nObj) - solutionJ.getObjective(nObj);
distance += Math.pow(diff, 2.0);
} // for
// Return the euclidean distance
return Math.sqrt(distance);
} // distanceBetweenObjectives.
/**
* Returns the distance between two solutions in the search space.
*
* @param solutionI The first <code>Solution</code>.
* @param solutionJ The second <code>Solution</code>.
* @return the distance between solutions.
* @throws JMException
*/
public double distanceBetweenSolutions(Solution solutionI, Solution solutionJ)
throws JMException {
// ->Obtain his decision variables
Variable[] decisionVariableI = solutionI.getDecisionVariables();
Variable[] decisionVariableJ = solutionJ.getDecisionVariables();
double diff; // Auxiliar var
double distance = 0.0;
// -> Calculate the Euclidean distance
for (int i = 0; i < decisionVariableI.length; i++) {
diff = decisionVariableI[i].getValue() - decisionVariableJ[i].getValue();
distance += Math.pow(diff, 2.0);
} // for
// -> Return the euclidean distance
return Math.sqrt(distance);
} // distanceBetweenSolutions
