private void testAndCorrectNumerics(
CMAEvolutionaryAlgorithm algorithm, int N, List<Individual> individuals) {
/*
* Flat fitness, Test if funtion values are identical
*/
/*
* we should sort the individuals by fitness value
*/
Collections.sort(individuals, algorithm.getComparator());
if (algorithm.getGenerations() > 0) {
if (individuals.get(0).getFitness()
== individuals
.get((int) Math.min(algorithm.getLambda() - 1, algorithm.getLambda() / 2.0 + 1) - 1)
.getFitness()) {
if (debug) {
System.err.println(
"WARNING - Flat fitness landscape, consider reformulation of fitness,"
+ "step-size increased");
}
algorithm.setSigma(
algorithm.getSigma() * Math.exp((0.2 + algorithm.getCs() / algorithm.getDamps())));
}
}
/*
* Align (renormalize) scale C and (consequently sigma)
*/
/*
* e.g. for infinite stationary state simulations (noise handling needs to be introduces for
* that)
*/
/*
* handling needs to be introduced for that)
*/
double fac = 1;
if (StatUtils.max(algorithm.getDiag()) < 1.0e-6) {
fac = 1.0 / StatUtils.max(algorithm.getDiag());
} else if (StatUtils.min(algorithm.getDiag()) > 1.0e+4) {
fac = 1.0 / StatUtils.min(algorithm.getDiag());
}
if (fac != 1.0) {
algorithm.setSigma(algorithm.getSigma() / fac);
for (int i = 0; i < N; i++) {
algorithm.getPc()[i] *= fac;
algorithm.getDiag()[i] *= fac;
for (int j = 0; j <= i; j++) {
algorithm.getC()[i][j] *= fac * fac;
}
}
}
}
