void GaussianMutation(IEvolutionState state, IMersenneTwister random, FloatVectorSpecies species, int index)
{
double val;
double min = species.GetMinGene(index);
double max = species.GetMaxGene(index);
double stdev = species.GetGaussMutationStdev(index);
int outOfBoundsLeftOverTries = species.OutOfBoundsRetries;
bool givingUpAllowed = species.OutOfBoundsRetries != 0;
do
{
val = random.NextGaussian() * stdev + genome[index];
outOfBoundsLeftOverTries--;
if (species.GetMutationIsBounded(index) && (val > max || val < min))
{
if (givingUpAllowed && (outOfBoundsLeftOverTries == 0))
{
val = min + random.NextFloat() * (max - min);
species.OutOfRangeRetryLimitReached(state);// it better get inlined
break;
}
}
else
{
break;
}
}while (true);
genome[index] = val;
}
void IntegerRandomWalkMutation(IMersenneTwister random, FloatVectorSpecies species, int index)
{
double min = species.GetMinGene(index);
double max = species.GetMaxGene(index);
if (!species.GetMutationIsBounded(index))
{
// okay, technically these are still bounds, but we can't go beyond this without weird things happening
max = MAXIMUM_INTEGER_IN_DOUBLE;
min = -(max);
}
do
{
int n = (int)(random.NextBoolean() ? 1 : -1);
double g = Math.Floor(genome[index]);
if ((n == 1 && g < max) ||
(n == -1 && g > min))
{
genome[index] = g + n;
}
else if ((n == -1 && g < max) ||
(n == 1 && g > min))
{
genome[index] = g - n;
}
}while (random.NextBoolean(species.GetRandomWalkProbability(index)));
}
void PolynomialMutation(IEvolutionState state, IMersenneTwister random, FloatVectorSpecies species, int index)
{
double eta_m = species.GetMutationDistributionIndex(index);
bool alternativePolynomialVersion = species.GetPolynomialIsAlternative(index);
double rnd, delta1, delta2, mut_pow, deltaq;
double y, yl, yu, val, xy;
double y1;
y1 = y = genome[index]; // ind[index];
yl = species.GetMinGene(index); // min_realvar[index];
yu = species.GetMaxGene(index); // max_realvar[index];
delta1 = (y - yl) / (yu - yl);
delta2 = (yu - y) / (yu - yl);
int totalTries = species.OutOfBoundsRetries;
int tries = 0;
for (tries = 0; tries < totalTries || totalTries == 0; tries++) // keep trying until totalTries is reached if it's not zero. If it's zero, go on forever.
{
rnd = random.NextDouble();
mut_pow = 1.0 / (eta_m + 1.0);
if (rnd <= 0.5)
{
xy = 1.0 - delta1;
val = 2.0 * rnd + (alternativePolynomialVersion ? (1.0 - 2.0 * rnd) * (Math.Pow(xy, (eta_m + 1.0))) : 0.0);
deltaq = Math.Pow(val, mut_pow) - 1.0;
}
else
{
xy = 1.0 - delta2;
val = 2.0 * (1.0 - rnd) + (alternativePolynomialVersion ? 2.0 * (rnd - 0.5) * (Math.Pow(xy, (eta_m + 1.0))) : 0.0);
deltaq = 1.0 - (Math.Pow(val, mut_pow));
}
y1 = y + deltaq * (yu - yl);
if (!species.GetMutationIsBounded(index) || (y1 >= yl && y1 <= yu))
{
break; // yay, found one
}
}
// at this point, if tries is totalTries, we failed
if (totalTries != 0 && tries == totalTries)
{
// just randomize
y1 = (double)(species.GetMinGene(index) + random.NextDouble(true, true) * (species.GetMaxGene(index) - species.GetMinGene(index))); //(double)(min_realvar[index] + random.NextDouble() * (max_realvar[index] - min_realvar[index]));
species.OutOfRangeRetryLimitReached(state); // it better get inlined
}
genome[index] = y1; // ind[index] = y1;
}