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25 //
26 // G4ImportanceAlgorithm implementation
27 //
28 // Author: Michael Dressel (CERN), 2002
29 // ----------------------------------------------------------------------
30
31 #include "G4Types.hh"
32 #include "Randomize.hh"
33 #include "G4Threading.hh"
34 #include "G4AutoLock.hh"
35
36 #include "G4ImportanceAlgorithm.hh"
37
38 #include <sstream>
39
40 namespace
41 {
42 G4Mutex ImportanceMutex = G4MUTEX_INITIALIZER;
43 }
44
45 G4ImportanceAlgorithm::G4ImportanceAlgorithm() = default;
46
47 G4ImportanceAlgorithm::~G4ImportanceAlgorithm() = default;
48
49 G4Nsplit_Weight
50 G4ImportanceAlgorithm::Calculate(G4double ipre,
51 G4double ipost,
52 G4double init_w) const
53 {
54 G4AutoLock l(&ImportanceMutex);
55 G4Nsplit_Weight nw;
56 if (ipost>0.)
57 {
58 if (!(ipre>0.))
59 {
60 Error("Calculate() - ipre==0.");
61 }
62 G4double ipre_over_ipost = ipre/ipost;
63 if ((ipre_over_ipost<0.25 || ipre_over_ipost> 4) && !fWarned)
64 {
65 std::ostringstream os;
66 os << "Calculate() - ipre_over_ipost ! in [0.25, 4]." << G4endl
67 << "ipre_over_ipost = " << ipre_over_ipost << ".";
68 Warning(os.str());
69 fWarned = true;
70 if (ipre_over_ipost<=0)
71 {
72 Error("Calculate() - ipre_over_ipost<=0.");
73 }
74 }
75 if (init_w<=0.)
76 {
77 Error("Calculate() - iniitweight<= 0. found!");
78 }
79
80 // default geometrical splitting
81 // in integer mode
82 // for ipre_over_ipost <= 1
83 G4double inv = 1./ipre_over_ipost;
84 nw.fN = static_cast<G4int>(inv);
85 nw.fW = init_w * ipre_over_ipost;
86
87 // geometrical splitting for double mode
88 if (ipre_over_ipost<1)
89 {
90 if ( static_cast<G4double>(nw.fN) != inv)
91 {
92 // double mode
93 // probability p for splitting into n+1 tracks
94 G4double p = inv - nw.fN;
95 // get a random number out of [0,1)
96 G4double r = G4UniformRand();
97 if (r<p)
98 {
99 ++nw.fN;
100 }
101 }
102 }
103 else if (ipre_over_ipost>1) // russian roulette
104 {
105 // probabiity for killing track
106 G4double p = 1-inv;
107 // get a random number out of [0,1)
108 G4double r = G4UniformRand();
109 if (r<p)
110 {
111 // kill track
112 nw.fN = 0;
113 nw.fW = 0;
114 }
115 else
116 {
117 nw.fN = 1;
118 }
119 }
120 }
121 l.unlock();
122
123 return nw;
124 }
125
126 void G4ImportanceAlgorithm::Error(const G4String& msg) const
127 {
128 G4Exception("G4ImportanceAlgorithm::Error()",
129 "GeomBias0002", FatalException, msg);
130 }
131
132 void G4ImportanceAlgorithm::Warning(const G4String& msg) const
133 {
134 G4Exception("G4ImportanceAlgorithm::Warning()",
135 "GeomBias1001", JustWarning, msg);
136 }
137