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geant4/source/geometry/biasing/include/G4WeightWindowAlgorithm.hh
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//
// G4WeightWindowAlgorithm
//
// Class description:
//
// Implementation of a weight window algorithm.
// The arguments in the constructor configure the algorithm:
// - upperLimitFactor: the factor defining the upper weight limit
// W_u = upperLimitFactor * W_l (W_l lower weight bound)
// - survivalFactor: used in calculating the survival weight
// W_s = survivalFactor * W_l
// - maxNumberOfSplits: the maximal number of splits allowed
// to be created in one go, and the reciprocal of the minimal
// survival probability in case of Russian roulette
//
// In case of upperLimitFactor=survivalFactor=1 the algorithm becomes
// the expected weight algorithm of the importance sampling technique.
//
// See also G4VWeightWindowAlgorithm.
// Author: Michael Dressel (CERN), 2003
// ----------------------------------------------------------------------
#ifndef G4WEIGHTWINDOWALGORITHM_HH
#define G4WEIGHTWINDOWALGORITHM_HH
#include "G4Nsplit_Weight.hh"
#include "G4VWeightWindowAlgorithm.hh"
/**
* @brief G4WeightWindowAlgorithm is a concrete implementation of a weight
* window algorithm.
*/
class G4WeightWindowAlgorithm : public G4VWeightWindowAlgorithm
{
public:
/**
* Constructor. The arguments configure the algorithm.
* In case of upperLimitFactor=survivalFactor=1 the algorithm becomes
* the expected weight algorithm of the importance sampling technique.
* @param[in] upperLimitFactor The factor defining the upper weight limit
* W_u = upperLimitFactor * W_l (W_l lower weight bound).
* @param[in] survivalFactor uUsed in calculating the survival weight
* W_s = survivalFactor * W_l.
* @param[in] maxNumberOfSplits The maximal number of splits allowed
* to be created in one go, and the reciprocal of the minimal
* survival probability in case of Russian roulette.
*/
G4WeightWindowAlgorithm(G4double upperLimitFactor = 5,
G4double survivalFactor = 3,
G4int maxNumberOfSplits = 5);
/**
* Default Destructor.
*/
~G4WeightWindowAlgorithm() override = default;
/**
* Calculates the number of tracks and their weight according
* to the initial track weight and the lower energy bound.
*/
G4Nsplit_Weight Calculate(G4double init_w,
G4double lowerWeightBound) const override;
private:
G4double fUpperLimitFactor = 0.0;
G4double fSurvivalFactor = 0.0;
G4int fMaxNumberOfSplits = 0;
};
#endif