| Geant4 Cross Reference |
1 // 1
2 // *******************************************
3 // * License and Disclaimer
4 // *
5 // * The Geant4 software is copyright of th
6 // * the Geant4 Collaboration. It is provided
7 // * conditions of the Geant4 Software License
8 // * LICENSE and available at http://cern.ch/
9 // * include a list of copyright holders.
10 // *
11 // * Neither the authors of this software syst
12 // * institutes,nor the agencies providing fin
13 // * work make any representation or warran
14 // * regarding this software system or assum
15 // * use. Please see the license in the file
16 // * for the full disclaimer and the limitatio
17 // *
18 // * This code implementation is the result
19 // * technical work of the GEANT4 collaboratio
20 // * By using, copying, modifying or distri
21 // * any work based on the software) you ag
22 // * use in resulting scientific publicati
23 // * acceptance of all terms of the Geant4 Sof
24 // *******************************************
25 //
26 // G4BFieldIntegrationDriver implementation
27 //
28 // Specialized integration driver for pure mag
29 //
30 // Author: D.Sorokin
31 // -------------------------------------------
32
33 #include "G4BFieldIntegrationDriver.hh"
34
35 #include "G4FieldTrack.hh"
36 #include "G4FieldUtils.hh"
37 #include "G4Exception.hh"
38 #include "G4PhysicalConstants.hh"
39 #include "G4SystemOfUnits.hh"
40 #include "templates.hh"
41
42
43 namespace {
44
45 G4Mag_EqRhs* toMagneticEquation(G4EquationOfMo
46 {
47 auto e = dynamic_cast<G4Mag_EqRhs*>(equati
48
49 if (e == nullptr)
50 {
51 G4Exception("G4BFieldIntegrationDriver
52 "GeomField0003", FatalErro
53 "Works only with G4Mag_EqR
54 }
55
56 return e;
57 }
58
59 } // namespace
60
61
62 G4BFieldIntegrationDriver::G4BFieldIntegration
63 std::unique_ptr<G4VIntegrationDriver> smal
64 std::unique_ptr<G4VIntegrationDriver> larg
65 : fSmallStepDriver(std::move(smallStepDriv
66 fLargeStepDriver(std::move(largeStepDriv
67 fCurrDriver(fSmallStepDriver.get()),
68 fEquation(toMagneticEquation(fCurrDriver
69 {
70 if (fSmallStepDriver->GetEquationOfMotion(
71 != fLargeStepDriver->GetEquationOfMotion(
72 {
73 G4Exception("G4BFieldIntegrationDriver
74 "GeomField1001", FatalExce
75 }
76 }
77
78 G4double G4BFieldIntegrationDriver::AdvanceCho
79
80
81
82 {
83 const G4double radius = CurvatureRadius(yC
84
85 G4VIntegrationDriver* driver = nullptr;
86 if (chordDistance < 2 * radius)
87 {
88 stepMax = std::min(stepMax, twopi * ra
89 driver = fSmallStepDriver.get();
90 ++fSmallDriverSteps;
91 } else
92 {
93 driver = fLargeStepDriver.get();
94 ++fLargeDriverSteps;
95 }
96
97 if (driver != fCurrDriver)
98 {
99 driver->OnComputeStep();
100 }
101
102 fCurrDriver = driver;
103
104 return fCurrDriver->AdvanceChordLimited(yC
105 ep
106 }
107
108 void
109 G4BFieldIntegrationDriver::SetEquationOfMotion
110 {
111 fEquation = toMagneticEquation(equation);
112 fSmallStepDriver->SetEquationOfMotion(equa
113 fLargeStepDriver->SetEquationOfMotion(equa
114 }
115
116 G4double
117 G4BFieldIntegrationDriver::CurvatureRadius(con
118 {
119 G4double field[G4Field::MAX_NUMBER_OF_COMP
120
121 GetFieldValue(track, field);
122
123 const G4double Bmag2 = field[0] * field[
124 + field[1] * field[
125 + field[2] * field[
126 if (Bmag2 == 0.0 )
127 {
128 return DBL_MAX;
129 }
130
131 const G4double momentum2 = track.GetMoment
132 const G4double fCof_inv = eplus / std::abs
133
134 return std::sqrt(momentum2 / Bmag2) * fCof
135 }
136
137 void
138 G4BFieldIntegrationDriver::GetFieldValue(const
139 G4dou
140 {
141 G4ThreeVector pos= track.GetPosition();
142 G4double positionTime[4]= { pos.x(), pos.y
143 track.GetLabTi
144
145 fEquation->GetFieldValue(positionTime, Fie
146 }
147
148 void G4BFieldIntegrationDriver::PrintStatistic
149 {
150 const auto totSteps = fSmallDriverSteps +
151 const auto toFraction = [&](double value)
152
153 G4cout << "============= G4BFieldIntegrati
154 << "total steps " << totSteps << "
155 << "smallDriverSteps " << toFractio
156 << "largeDriverSteps " << toFractio
157 << "===============================
158 }
159