| Geant4 Cross Reference |
1 //
2 // ********************************************************************
3 // * License and Disclaimer *
4 // * *
5 // * The Geant4 software is copyright of the Copyright Holders of *
6 // * the Geant4 Collaboration. It is provided under the terms and *
7 // * conditions of the Geant4 Software License, included in the file *
8 // * LICENSE and available at http://cern.ch/geant4/license . These *
9 // * include a list of copyright holders. *
10 // * *
11 // * Neither the authors of this software system, nor their employing *
12 // * institutes,nor the agencies providing financial support for this *
13 // * work make any representation or warranty, express or implied, *
14 // * regarding this software system or assume any liability for its *
15 // * use. Please see the license in the file LICENSE and URL above *
16 // * for the full disclaimer and the limitation of liability. *
17 // * *
18 // * This code implementation is the result of the scientific and *
19 // * technical work of the GEANT4 collaboration. *
20 // * By using, copying, modifying or distributing the software (or *
21 // * any work based on the software) you agree to acknowledge its *
22 // * use in resulting scientific publications, and indicate your *
23 // * acceptance of all terms of the Geant4 Software license. *
24 // ********************************************************************
25 //
26 // G4NystromRK4
27 //
28 // Class description:
29 //
30 // Integrates the equations of the motion of a particle in a magnetic field
31 // using 4th Runge-Kutta-Nystrom method with errors estimation
32 // (ATL-SOFT-PUB-2009-01)
33 // Current form can be used only for 'pure' magnetic field.
34 // Notes: 1) field must be time-independent.
35 // 2) time is not integrated
36
37 // Created: I.Gavrilenko, 15.05.2009 (as G4AtlasRK4)
38 // Adaptations: J.Apostolakis, November 2009
39 // -------------------------------------------------------------------
40
41 #ifndef G4NYSTROMRK4_HH
42 #define G4NYSTROMRK4_HH
43
44 #include "G4MagIntegratorStepper.hh"
45 #include "G4Mag_EqRhs.hh"
46 #include "G4CachedMagneticField.hh"
47 #include "G4ThreeVector.hh"
48
49 #include <memory>
50
51 class G4NystromRK4 : public G4MagIntegratorStepper
52 {
53 public:
54
55 G4NystromRK4(G4Mag_EqRhs* EquationMotion,
56 G4double distanceConstField = 0.0);
57 // Can be used only for Magnetic Fields - and for 6 variables (x,p)
58 ~G4NystromRK4() override = default;
59
60 void Stepper(const G4double y[],
61 const G4double dydx[],
62 G4double hstep,
63 G4double yOut[],
64 G4double yError[]) override;
65 // Single call for integration result and error
66 // Provides error via analytical method
67
68 void SetDistanceForConstantField(G4double length);
69 G4double GetDistanceForConstantField() const;
70
71 G4int IntegratorOrder() const override { return 4; }
72 G4double DistChord() const override;
73
74 private:
75
76 inline void GetFieldValue(const G4double point[4], G4double field[3]);
77 inline G4double GetFCof();
78
79 G4CachedMagneticField* GetField();
80 const G4CachedMagneticField* GetField() const;
81
82 G4double fMomentum = 0.0;
83 G4double fMomentum2 = 0.0;
84 G4double fInverseMomentum = 0.0;
85 G4double fCoefficient = 0.0;
86 G4ThreeVector fInitialPoint;
87 G4ThreeVector fMidPoint;
88 G4ThreeVector fEndPoint;
89
90 std::unique_ptr<G4CachedMagneticField> fCachedField;
91 };
92
93 #include "G4NystromRK4.icc"
94
95 #endif
96