FloatingPointCrsSbx.cpp

#include "../ECF_base.h"
#include "FloatingPoint.h"
#include <math.h>
 
 
namespace FloatingPoint
{
 
void FloatingPointCrsSbx::registerParameters(StateP state)
{
    myGenotype_->registerParameter(state, "crx.sbx", (voidP) new double(0), ECF::DOUBLE);
    state->getRegistry()->registerEntry("crx.sbx.ni", (voidP) new uint(1), ECF::UINT);
}
 
 
bool FloatingPointCrsSbx::initialize(StateP state)
{
    voidP sptr = myGenotype_->getParameterValue(state, "crx.sbx");
    probability_ = *((double*)sptr.get());
 
    voidP par = state->getRegistry()->getEntry("crx.sbx.ni");
    ni = *((uint*) par.get());
 
    return true;
}
 
 
bool FloatingPointCrsSbx::mate(GenotypeP gen1, GenotypeP gen2, GenotypeP child)
{
    FloatingPoint* p1 = (FloatingPoint*) (gen1.get());
    FloatingPoint* p2 = (FloatingPoint*) (gen2.get());
    FloatingPoint* ch = (FloatingPoint*) (child.get());
 
    // repeat for each variable
    for(uint i = 0; i < p1->realValue.size(); i++) {
        double p1x = p1->realValue[i];
        double p2x = p2->realValue[i];
        
        // determine smaller and greater parent values
        double low = p1x, high = p2x;
        if(p2x < p1x) {
            low  = p2x;
            high = p1x;
        }
 
        // check for close or same parents
        if(fabs(high - low) < 1.e-12) {
            ch->realValue[i] = (high + low) / 2;
            continue;
        }
 
        // determine min[(low - LBound), (UBound - high)]
        double min = low - p1->getLBound();
        if((p1->getUBound() - high) < min)
            min = p1->getUBound() - high;
 
        // determine beta and alpha
        double beta = 1 + 2 * min / (high - low);
        double alpha = 2 - 1 / pow(beta, 1. + ni);
 
        double u = state_->getRandomizer()->getRandomDouble();
        // scale down to avoid u == 1
        u *= 0.999;
 
        double beta_dash;
        // if u is smaller than 1/alpha perform a contracting crossover
        if (u <= (1. / alpha)) {
            beta_dash = pow(alpha * u, 1.0 / (ni + 1.0));
        }
        // otherwise perform an expanding crossover
        else {
            beta_dash = pow(1. / (2. - alpha * u), 1.0 / (ni + 1.0));
        }
 
        // apply beta_dash
        switch (state_->getRandomizer()->getRandomInteger(0, 1)) {
            case 0: ch->realValue[i] = ((p1->realValue[i] + p2->realValue[i])/2.0) - beta_dash * 0.5 * fabs(p1->realValue[i] - p2->realValue[i]);
                    break;
            case 1: ch->realValue[i] = ((p1->realValue[i] + p2->realValue[i])/2.0) + beta_dash * 0.5 * fabs(p1->realValue[i] - p2->realValue[i]);
        }
    }
 
    return true;
}
 
}