@Override
public List<Individual> operate(EvolutionaryAlgorithm algorithm, List<Individual> individuals)
throws OperatorException {
List<Individual> new_population = new ArrayList<Individual>(individuals.size());
CMAEvolutionaryAlgorithm alg = (CMAEvolutionaryAlgorithm) algorithm;
debug = algorithm.isDebug();
double[] chromosome;
int N = individuals.get(0).getDimension();
countCUpdatesSinceEigenupdate = alg.getCountCupdatesSinceEigenupdate();
// latest possibility to generate B and diagD:
eidgendecomposition(alg, N, 0);
// ensure minimal and maximal standard deviation:
double minsqrtdiagC = Math.sqrt(StatUtils.min(alg.diag(alg.getC())));
double maxsqrtdiagC = Math.sqrt(StatUtils.max(alg.diag(alg.getC())));
/*
* TODO: test if it is necessary *
*/
for (int i = 0; i < individuals.size(); i++) {
new_population.add((Individual) individuals.get(i).clone());
}
if (lowerStandardDeviation != null && lowerStandardDeviation.length > 0) {
for (int i = 0; i < N; i++) {
double d = lowerStandardDeviation[Math.min(i, lowerStandardDeviation.length - 1)];
if (d > alg.getSigma() * minsqrtdiagC) {
alg.setSigma(d / minsqrtdiagC);
}
}
}
if (upperStandardDeviation != null && upperStandardDeviation.length > 0) {
for (int i = 0; i < N; i++) {
double d = upperStandardDeviation[Math.min(i, upperStandardDeviation.length - 1)];
if (d < alg.getSigma() * maxsqrtdiagC) {
alg.setSigma(d / maxsqrtdiagC);
}
}
}
testAndCorrectNumerics(alg, N, new_population);
double[] artmp = new double[N];
/*
* Sample the distribution
*/
for (int iNk = 0; iNk < alg.getLambda(); iNk++) {
chromosome = new_population.get(iNk).getChromosomeAt(0);
if (alg.getFlgDiag()) {
for (int i = 0; i < N; i++) {
chromosome[i] =
this.checkBounds(
alg,
alg.getxMean()[i] + alg.getSigma() * alg.getDiag()[i] * EAFRandom.nextGaussian());
}
} else {
for (int i = 0; i < N; i++) {
artmp[i] = alg.getDiag()[i] * EAFRandom.nextGaussian();
}
/*
* add mutation (sigma * B * (D*z))
*/
for (int i = 0; i < N; i++) {
double sum = 0.0;
for (int j = 0; j < N; j++) {
sum += alg.getB()[i][j] * artmp[j];
}
chromosome[i] = this.checkBounds(alg, alg.getxMean()[i] + alg.getSigma() * sum);
}
}
new_population.get(iNk).setChromosomeAt(0, chromosome);
}
return new_population;
}
