Gabriele Cosmo
110 lines
3.4 KiB
C++
110 lines
3.4 KiB
C++
//
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// ********************************************************************
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// * DISCLAIMER *
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// * *
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// * The following disclaimer summarizes all the specific disclaimers *
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// * of contributors to this software. The specific disclaimers,which *
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// * govern, are listed with their locations in: *
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// * http://cern.ch/geant4/license *
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// * *
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// * Neither the authors of this software system, nor their employing *
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// * institutes,nor the agencies providing financial support for this *
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// * work make any representation or warranty, express or implied, *
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// * regarding this software system or assume any liability for its *
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// * use. *
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// * *
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// * This code implementation is the intellectual property of the *
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// * GEANT4 collaboration. *
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// * By copying, distributing or modifying the Program (or any work *
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// * based on the Program) you indicate your acceptance of this *
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// * statement, and all its terms. *
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// ********************************************************************
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//
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//
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// $Id: G4WeightWindowAlgorithm.cc,v 1.7 2003/08/19 15:16:56 dressel Exp $
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// GEANT4 tag $Name: geant4-08-00 $
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//
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// ----------------------------------------------------------------------
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// GEANT 4 class source file
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//
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// G4WeightWindowAlgorithm.cc
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//
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// ----------------------------------------------------------------------
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#include "G4WeightWindowAlgorithm.hh"
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#include "Randomize.hh"
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G4WeightWindowAlgorithm::
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G4WeightWindowAlgorithm(G4double upperLimitFaktor,
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G4double survivalFaktor,
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G4int maxNumberOfSplits) :
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fUpperLimitFaktor(upperLimitFaktor),
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fSurvivalFaktor(survivalFaktor),
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fMaxNumberOfSplits(maxNumberOfSplits)
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{}
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G4WeightWindowAlgorithm::~G4WeightWindowAlgorithm()
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{}
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G4Nsplit_Weight
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G4WeightWindowAlgorithm::Calculate(G4double init_w,
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G4double lowerWeightBound) const {
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G4double survivalWeight = lowerWeightBound * fSurvivalFaktor;
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G4double upperWeight = lowerWeightBound * fUpperLimitFaktor;
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// initialize return value for case weight in window
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G4Nsplit_Weight nw;
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nw.fN = 1;
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nw.fW = init_w;
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if (init_w > upperWeight) {
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// splitting
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G4double wi_ws = init_w/survivalWeight;
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G4int int_wi_ws = static_cast<int>(wi_ws);
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// values in case integer mode or in csae of double
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// mode and the lower number of splits will be diced
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nw.fN = int_wi_ws;
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nw.fW = survivalWeight;
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if (wi_ws <= fMaxNumberOfSplits) {
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if (wi_ws > int_wi_ws) {
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// double mode
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G4double p2 = wi_ws - int_wi_ws;
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G4double r = G4UniformRand();
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if (r<p2) {
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nw.fN = int_wi_ws + 1;
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}
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}
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}
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else {
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// fMaxNumberOfSplits < wi_ws
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nw.fN = fMaxNumberOfSplits;
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nw.fW = init_w/fMaxNumberOfSplits;
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}
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} else if (init_w < lowerWeightBound) {
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// Russian roulette
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G4double wi_ws = init_w/survivalWeight;
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G4double p = std::max(wi_ws,1./fMaxNumberOfSplits);
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G4double r = G4UniformRand();
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if (r<p){
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nw.fW = init_w/p;
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nw.fN = 1;
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} else {
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nw.fW = 0;
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nw.fN = 0;
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}
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}
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// else do nothing
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return nw;
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}
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