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src/ell/MinimumSelector.cc

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#include "ell/MinimumSelector.hh"

namespace ell
{
    
    MinimumSelector::~MinimumSelector()
    {
    }

} // namespace ell

#include "biu/RandomNumberFactory.hh"

namespace ell
{
    MS_Uniform::
	MS_Uniform()
    {
    }
    
    
    MS_Uniform::
	~MS_Uniform()
    {
    }

    size_t
    MS_Uniform::
	select(    const LandscapeTopology* const lt
            , const bool minimaChanged )
    {
        size_t selected = LandscapeTopology::INVALID_INDEX;
        
          // select uniformly a minimum 
        if (lt->getMinCount() > 0) {
            selected = (size_t)biu::RNF::getRN((unsigned int)lt->getMinCount());
        }   
        
        return selected;
    }
    
} // namespace ell

#include <cmath>
#include <algorithm>

namespace ell
{
    MS_Boltzmann::
	MS_Boltzmann( const double shiftFactor_ )
      : shiftFactor( shiftFactor_ )
        , boltzWeightSum()
    {
    }
    
    
    MS_Boltzmann::
	~MS_Boltzmann()
    {
    }

    size_t
    MS_Boltzmann::
	select(    const LandscapeTopology* const lt
            , const bool minimaChanged )
    {
        size_t selected = LandscapeTopology::INVALID_INDEX;
        
          // select uniformly a minimum 
        if (lt->getMinCount() > 0) {
              // check if boltzWeightSum has to be updated
            if (minimaChanged || boltzWeightSum.size()!=(lt->getMinCount()+1)) {
                  // resize the weight sum container
                boltzWeightSum.resize(lt->getMinCount()+1,0.0);
                  // sum successively over the Boltzmann weights
                boltzWeightSum[0] = 0.0;
                for (size_t i=1; i<boltzWeightSum.size(); i++) {
                    boltzWeightSum[i] = exp( -lt->getMin(i-1)->getEnergy()
                                            / LandscapeTopology::BOLTZMANN_KT )
                                        + boltzWeightSum[i-1];
                }
            }
              // calculate a random number in interval [0,fullBoltzWeightSum]
            double selectedProp = (((double) biu::RNF::getRN()) 
                                        / ((double) biu::RNF::getMaxRN())) 
                                    * (*(boltzWeightSum.rbegin()));
              // get index of the corresponding interval to find the minimum
            std::vector<double>::const_iterator pos
                = std::lower_bound( boltzWeightSum.begin()
                                    , boltzWeightSum.end()
                                    , selectedProp );
              // recalculate position from iterators
            selected = (size_t)(pos - boltzWeightSum.begin());
        }
        
        return selected;
    }
    
} // namespace ell