include/Geant4/G4HelixMixedStepper.hh

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0025 //
0026 // G4HelixMixedStepper
0027 //
0028 // Class description:
0029 //
0030 // G4HelixMixedStepper split the Method used for Integration in two:
0031 //
0032 // If Stepping Angle ( h / R_curve) < pi/3 : use Stepper for small step
0033 //
0034 // Else use  HelixExplicitEuler Stepper
0035 //
0036 // Stepper for the small step is G4ClassicalRK4 by default, but
0037 //  it possible to choose other stepper,like G4CashKarpRK45 or G4RKG3_Stepper,
0038 //  by setting StepperNumber : new HelixMixedStepper(EqRhs,N)
0039 //
0040 //  N=2  G4SimpleRunge;            N=3  G4SimpleHeum;
0041 //  N=4  G4ClassicalRK4;
0042 //  N=6  G4HelixImplicitEuler;     N=7  G4HelixSimpleRunge;
0043 //  N=8  G4CashKarpRK45;           N=9  G4ExactHelixStepper;
0044 //  N=10 G4RKG3_Stepper;           N=13 G4NystromRK4
0045 //  N=23 BogackiShampine23         N=145 TsitourasRK45
0046 //  N=45 BogackiShampine45         N=745 DormandPrince745 (ie DoPri5)
0047 //
0048 //  For completeness also available are:
0049 //  N=11 G4ExplicitEuler           N=12 G4ImplicitEuler;   -- Likely poor
0050 //  N=5  G4HelixExplicitEuler (testing only)
0051 //  For recommendations see comments in 'SetupStepper' method.
0052 //
0053 //  Note: Like other helix steppers, only applicable in pure magnetic field
0054
0055 // Created: T.Nikitina, CERN - 18.05.2007, derived from G4ExactHelicalStepper
0056 // -------------------------------------------------------------------
0057 #ifndef G4HELIXMIXEDSTEPPER_HH
0058 #define G4HELIXMIXEDSTEPPER_HH
0059
0060 #include "G4MagHelicalStepper.hh"
0061
0062 class G4HelixMixedStepper : public G4MagHelicalStepper
0063 {
0064   public:
0065
0066     G4HelixMixedStepper(G4Mag_EqRhs* EqRhs,
0067                         G4int StepperNumber = -1,
0068                         G4double Angle_threshold = -1.0);
0069    ~G4HelixMixedStepper() override;
0070
0071     void Stepper( const G4double y[],
0072                   const G4double dydx[],
0073                         G4double h,
0074                         G4double yout[],
0075                         G4double yerr[] ) override;
0076       // Step 'integration' for step size 'h'
0077       // If SteppingAngle= h/R_curve < pi/3 uses default RK stepper
0078       // else use Helix Fast Method
0079
0080     void DumbStepper( const G4double y[],
0081                             G4ThreeVector  Bfld,
0082                             G4double       h,
0083                             G4double       yout[]) override;
0084
0085     G4double DistChord() const override;
0086       // Estimate maximum distance of curved solution and chord ...
0087
0088     inline void SetVerbose (G4int newvalue) { fVerbose = newvalue; }
0089
0090     void PrintCalls();
0091     G4MagIntegratorStepper* SetupStepper(G4Mag_EqRhs* EqRhs, G4int StepperName);
0092
0093     inline void SetAngleThreshold( G4double val ) { fAngle_threshold = val; }
0094     inline G4double GetAngleThreshold() { return fAngle_threshold; }
0095     inline G4int IntegratorOrder() const override { return 4; }
0096
0097   private:
0098
0099     G4MagIntegratorStepper* fRK4Stepper = nullptr;
0100       // Mixed Integration RK4 for 'small' steps
0101     G4int fStepperNumber = -1;
0102       // Int ID of RK stepper
0103     G4double fAngle_threshold = -1.0;
0104       // Threshold angle (in radians ) - above it Helical stepper is used
0105
0106   private:
0107
0108     G4int fVerbose = 0;
0109
0110     G4int fNumCallsRK4 = 0;
0111     G4int fNumCallsHelix = 0;
0112       // Used for statistic = how many calls to different steppers
0113 };
0114
0115 #endif