| Geant4 Cross Reference |
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25 //
26 // G4IntegrationDriver
27 //
28 // Class description:
29 //
30 // Templated driver class which controls the integration error of a
31 // Runge-Kutta stepper.
32 // It's purpose is to provide a replacement of G4MagIntegratorDriver
33 // and work for all types of steppers.
34 // It will serve as the driver of choice for steppers which do not
35 // have extra capabilities, in particular First Same As Last (FSAL)
36 // and/or interpolation.
37
38 // Author: Dmitry Sorokin, Google Summer of Code 2017
39 // Supervision: John Apostolakis, CERN
40 // --------------------------------------------------------------------
41 #ifndef G4INTEGRATIONDRIVER_HH
42 #define G4INTEGRATIONDRIVER_HH
43
44 #include "G4RKIntegrationDriver.hh"
45 #include "G4ChordFinderDelegate.hh"
46
47 template <class T>
48 class G4IntegrationDriver : public G4RKIntegrationDriver<T>,
49 public G4ChordFinderDelegate<G4IntegrationDriver<T>>
50 {
51 public:
52
53 G4IntegrationDriver( G4double hminimum,
54 T* stepper,
55 G4int numberOfComponents = 6,
56 G4int statisticsVerbosity = 0 );
57 ~G4IntegrationDriver() override;
58
59 G4IntegrationDriver(const G4IntegrationDriver &) = delete;
60 const G4IntegrationDriver& operator =(const G4IntegrationDriver &) = delete;
61
62 G4double AdvanceChordLimited(G4FieldTrack& track,
63 G4double stepMax,
64 G4double epsStep,
65 G4double chordDistance) override;
66
67 void OnStartTracking() override;
68 void OnComputeStep(const G4FieldTrack* /*track*/ = nullptr) override {}
69 G4bool DoesReIntegrate() const override { return true; }
70
71 G4bool AccurateAdvance(G4FieldTrack& track,
72 G4double hstep,
73 G4double eps, // Requested y_err/hstep
74 G4double hinitial = 0 ) override;
75 // Integrates ODE from current s (s=s0) to s=s0+h with accuracy eps.
76 // On output track is replaced by value at end of interval.
77 // The concept is similar to the odeint routine from NRC p.721-722.
78
79 G4bool QuickAdvance( G4FieldTrack& fieldTrack,
80 const G4double dydx[],
81 G4double hstep,
82 G4double& dchord_step,
83 G4double& dyerr) override;
84 // QuickAdvance just tries one Step - it does not ensure accuracy.
85
86 void SetVerboseLevel(G4int newLevel) override;
87 G4int GetVerboseLevel() const override;
88
89 void StreamInfo( std::ostream& os ) const override;
90 // Write out the parameters / state of the driver
91
92 // Accessors
93 //
94 G4double GetMinimumStep() const;
95 void SetMinimumStep(G4double newval);
96
97 void OneGoodStep( G4double yVar[], // InOut
98 const G4double dydx[],
99 G4double& curveLength,
100 G4double htry,
101 G4double eps,
102 G4double& hdid,
103 G4double& hnext);
104 // This takes one Step that is of size htry, or as large
105 // as possible while satisfying the accuracy criterion of:
106 // yerr < eps * |y_end-y_start|
107
108 G4double GetSmallestFraction() const;
109 void SetSmallestFraction(G4double val);
110
111 protected:
112
113 void IncrementQuickAdvanceCalls();
114
115 private:
116
117 void CheckStep(const G4ThreeVector& posIn,
118 const G4ThreeVector& posOut,
119 G4double hdid);
120
121 G4double fMinimumStep;
122 // Minimum Step allowed in a Step (in absolute units)
123
124 G4double fSmallestFraction{1e-12};
125 // Smallest fraction of (existing) curve length - in relative units
126 // below this fraction the current step will be the last
127 // Expected range: smaller than 0.1 * epsilon and bigger than 5e-13
128 // Note: this range is not enforced.
129
130 G4int fVerboseLevel;
131 // Verbosity level for printing (debug, ..)
132 // Could be varied during tracking - to help identify issues
133
134 G4int fNoQuickAvanceCalls{0};
135 G4int fNoAccurateAdvanceCalls{0};
136 G4int fNoAccurateAdvanceBadSteps{0};
137 G4int fNoAccurateAdvanceGoodSteps{0};
138
139 using Base = G4RKIntegrationDriver<T>;
140 using ChordFinderDelegate = G4ChordFinderDelegate<G4IntegrationDriver<T>>;
141 };
142
143 #include "G4IntegrationDriver.icc"
144
145 #endif
146