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// $Id: G4WeightWindowAlgorithm.hh,v 1.7 2006/06/29 18:16:59 gunter Exp $
// GEANT4 tag $Name: geant4-09-02-ref-02 $
//
// ----------------------------------------------------------------------
// Class G4WeightWindowAlgorithm
// 
// Class description:
// Implementation of a weight window algorithm. 
// The arguments in the constructor configure the algorithm:
//   - upperLimitFaktor: the factor defining the upper weight limit 
//      W_u = upperLimitFaktor * W_l (W_l lower weight bound)
//   - survivalFaktor: used in calculating  the survival weight
//      W_s = survivalFaktor * 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 upperLimitFaktor=survivalFaktor=1 the algorithm
// becomes the expected weight algorithm of the importance sampling 
// technique.
//
// see also G4VWeightWindowAlgorithm.
//

// Author: Michael Dressel (Michael.Dressel@cern.ch)
// ----------------------------------------------------------------------
#ifndef G4WeightWindowAlgorithm_hh
#define G4WeightWindowAlgorithm_hh G4WeightWindowAlgorithm_hh 

#include "G4Nsplit_Weight.hh"
#include "G4VWeightWindowAlgorithm.hh"

class G4WeightWindowAlgorithm : public G4VWeightWindowAlgorithm
{

public:  // with description
  
  G4WeightWindowAlgorithm(G4double upperLimitFaktor = 5,
			  G4double survivalFaktor = 3,
			  G4int maxNumberOfSplits = 5);
  
  virtual ~G4WeightWindowAlgorithm();

  virtual G4Nsplit_Weight Calculate(G4double init_w,
				    G4double lowerWeightBound) const;
    // calculate number of tracks and their weight according
    // to the initial track weight and the lower energy bound

private:
  G4double fUpperLimitFaktor;
  G4double fSurvivalFaktor;
  G4int fMaxNumberOfSplits;
};

#endif