public Improvement findIncrementalImprovement(Optimizee optimizee, double jumpSize,
Improvement lastImprovement, Set<ParameterArray> cache) {
NumericParameterArray currentParams = this;
double oldFitness = currentParams.getFitness();
Vector oldGradient = null;
if (lastImprovement != null) {
oldFitness = lastImprovement.getParams().getFitness();
oldGradient = lastImprovement.getGradient();
}