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25 //
26 // G4HelixMixedStepper
27 //
28 // Class description:
29 //
30 // G4HelixMixedStepper split the Method used for Integration in two:
31 //
32 // If Stepping Angle ( h / R_curve) < pi/3 : use Stepper for small step
33 //
34 // Else use HelixExplicitEuler Stepper
35 //
36 // Stepper for the small step is G4ClassicalRK4 by default, but
37 // it possible to choose other stepper,like G4CashKarpRK45 or G4RKG3_Stepper,
38 // by setting StepperNumber : new HelixMixedStepper(EqRhs,N)
39 //
40 // N=2 G4SimpleRunge; N=3 G4SimpleHeum;
41 // N=4 G4ClassicalRK4;
42 // N=6 G4HelixImplicitEuler; N=7 G4HelixSimpleRunge;
43 // N=8 G4CashKarpRK45; N=9 G4ExactHelixStepper;
44 // N=10 G4RKG3_Stepper; N=13 G4NystromRK4
45 // N=23 BogackiShampine23 N=145 TsitourasRK45
46 // N=45 BogackiShampine45 N=745 DormandPrince745 (ie DoPri5)
47 //
48 // For completeness also available are:
49 // N=11 G4ExplicitEuler N=12 G4ImplicitEuler; -- Likely poor
50 // N=5 G4HelixExplicitEuler (testing only)
51 // For recommendations see comments in 'SetupStepper' method.
52 //
53 // Note: Like other helix steppers, only applicable in pure magnetic field
54
55 // Created: T.Nikitina, CERN - 18.05.2007, derived from G4ExactHelicalStepper
56 // -------------------------------------------------------------------
57 #ifndef G4HELIXMIXEDSTEPPER_HH
58 #define G4HELIXMIXEDSTEPPER_HH
59
60 #include "G4MagHelicalStepper.hh"
61
62 class G4HelixMixedStepper : public G4MagHelicalStepper
63 {
64 public:
65
66 G4HelixMixedStepper(G4Mag_EqRhs* EqRhs,
67 G4int StepperNumber = -1,
68 G4double Angle_threshold = -1.0);
69 ~G4HelixMixedStepper() override;
70
71 void Stepper( const G4double y[],
72 const G4double dydx[],
73 G4double h,
74 G4double yout[],
75 G4double yerr[] ) override;
76 // Step 'integration' for step size 'h'
77 // If SteppingAngle= h/R_curve < pi/3 uses default RK stepper
78 // else use Helix Fast Method
79
80 void DumbStepper( const G4double y[],
81 G4ThreeVector Bfld,
82 G4double h,
83 G4double yout[]) override;
84
85 G4double DistChord() const override;
86 // Estimate maximum distance of curved solution and chord ...
87
88 inline void SetVerbose (G4int newvalue) { fVerbose = newvalue; }
89
90 void PrintCalls();
91 G4MagIntegratorStepper* SetupStepper(G4Mag_EqRhs* EqRhs, G4int StepperName);
92
93 inline void SetAngleThreshold( G4double val ) { fAngle_threshold = val; }
94 inline G4double GetAngleThreshold() { return fAngle_threshold; }
95 inline G4int IntegratorOrder() const override { return 4; }
96
97 private:
98
99 G4MagIntegratorStepper* fRK4Stepper = nullptr;
100 // Mixed Integration RK4 for 'small' steps
101 G4int fStepperNumber = -1;
102 // Int ID of RK stepper
103 G4double fAngle_threshold = -1.0;
104 // Threshold angle (in radians ) - above it Helical stepper is used
105
106 private:
107
108 G4int fVerbose = 0;
109
110 G4int fNumCallsRK4 = 0;
111 G4int fNumCallsHelix = 0;
112 // Used for statistic = how many calls to different steppers
113 };
114
115 #endif
116