#include <G4ImportanceAlgorithm.hh>

Inheritance diagram for G4ImportanceAlgorithm:

Public Member Functions
	G4ImportanceAlgorithm ()

	~G4ImportanceAlgorithm () override

G4Nsplit_Weight	Calculate (G4double ipre, G4double ipost, G4double init_w) const override

Public Member Functions inherited from G4VImportanceAlgorithm
	G4VImportanceAlgorithm ()

virtual	~G4VImportanceAlgorithm ()

Detailed Description

Definition at line 41 of file G4ImportanceAlgorithm.hh.

Constructor & Destructor Documentation

◆ G4ImportanceAlgorithm()

G4ImportanceAlgorithm::G4ImportanceAlgorithm ( )

default

◆ ~G4ImportanceAlgorithm()

G4ImportanceAlgorithm::~G4ImportanceAlgorithm ( )

overridedefault

Member Function Documentation

◆ Calculate()

G4Nsplit_Weight G4ImportanceAlgorithm::Calculate	(	G4double	ipre,
		G4double	ipost,
		G4double	init_w ) const

overridevirtual

Implements G4VImportanceAlgorithm.

Definition at line 50 of file G4ImportanceAlgorithm.cc.

{
  G4AutoLock l(&ImportanceMutex);
  G4Nsplit_Weight nw;
  if (ipost>0.)
  {
    if (!(ipre>0.))
    {
      Error("Calculate() - ipre==0.");
    }
    G4double ipre_over_ipost = ipre/ipost;
    if ((ipre_over_ipost<0.25 || ipre_over_ipost> 4) && !fWarned)
    {
      std::ostringstream os;
      os << "Calculate() - ipre_over_ipost ! in [0.25, 4]." << G4endl
         << "ipre_over_ipost = " << ipre_over_ipost << ".";
      Warning(os.str());
      fWarned = true;
      if (ipre_over_ipost<=0)
      {
        Error("Calculate() - ipre_over_ipost<=0.");
      }
    }
    if (init_w<=0.)
    {
      Error("Calculate() - iniitweight<= 0. found!");
    }
 
    // default geometrical splitting 
    // in integer mode 
    // for ipre_over_ipost <= 1
    G4double inv = 1./ipre_over_ipost;
    nw.fN = static_cast<G4int>(inv);
    nw.fW = init_w * ipre_over_ipost;
    
    // geometrical splitting for double mode
    if (ipre_over_ipost<1)
    {
      if ( static_cast<G4double>(nw.fN) != inv)
      {
        // double mode
        // probability p for splitting into n+1 tracks
        G4double p = inv - nw.fN;
        // get a random number out of [0,1)
        G4double r = G4UniformRand();
        if (r<p)
        {
          ++nw.fN;
        } 
      }  
    }
    else if (ipre_over_ipost>1)   // russian roulette
    {
      // probabiity for killing track
      G4double p = 1-inv;
      // get a random number out of [0,1)
      G4double r = G4UniformRand();
      if (r<p)
      {
        // kill track
        nw.fN = 0;
        nw.fW = 0;
      }
      else
      {
        nw.fN = 1;     
      }
    }
  }
  l.unlock();
 
  return nw;
}