Fitness class (TFitness) is owned by classes from generic GA layers . This class contains methods for evaluation of gene quality. Fitness is calculated according to the expression specified in parameter file (see User's Guide ). This expression first undergoes certain steps guaranteeing maximum efficiency of fitness calculation as it is called very frequently. The calculation itself is evoked by a call to method TFitness::Compute(). Note that neural nets can also be used as a functor in the above expression. The result of one gene fitness evaluation is stored inside the gene (class TGen) in fitness attribute of type TFit. Important related topics are :