include/Geant4/G4IntegrationDriver.hh

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0024 // ********************************************************************
0025 //
0026 // G4IntegrationDriver
0027 //
0028 // Class description:
0029 //
0030 // Templated driver class which controls the integration error of a
0031 // Runge-Kutta stepper.
0032 // It's purpose is to provide a replacement of G4MagIntegratorDriver
0033 // and work for all types of steppers.
0034 // It will serve as the driver of choice for steppers which do not
0035 // have extra capabilities, in particular First Same As Last (FSAL)
0036 // and/or interpolation.
0037
0038 // Author: Dmitry Sorokin, Google Summer of Code 2017
0039 // Supervision: John Apostolakis, CERN
0040 // --------------------------------------------------------------------
0041 #ifndef G4INTEGRATIONDRIVER_HH
0042 #define G4INTEGRATIONDRIVER_HH
0043
0044 #include "G4RKIntegrationDriver.hh"
0045 #include "G4ChordFinderDelegate.hh"
0046
0047 template <class T>
0048 class G4IntegrationDriver : public G4RKIntegrationDriver<T>,
0049                             public G4ChordFinderDelegate<G4IntegrationDriver<T>>
0050 {
0051   public:
0052
0053     G4IntegrationDriver( G4double hminimum,
0054                          T*       stepper,
0055                          G4int    numberOfComponents = 6,
0056                          G4int    statisticsVerbosity = 0 );
0057    ~G4IntegrationDriver() override;
0058
0059     G4IntegrationDriver(const G4IntegrationDriver &) = delete;
0060     const G4IntegrationDriver& operator =(const G4IntegrationDriver &) = delete;
0061
0062     G4double AdvanceChordLimited(G4FieldTrack& track,
0063                                          G4double stepMax,
0064                                          G4double epsStep,
0065                                          G4double chordDistance) override;
0066
0067     void OnStartTracking() override;
0068     void OnComputeStep(const G4FieldTrack* /*track*/ = nullptr) override {}
0069     G4bool DoesReIntegrate() const override { return true; }
0070
0071     G4bool AccurateAdvance(G4FieldTrack& track,
0072                            G4double hstep,
0073                            G4double eps, // Requested y_err/hstep
0074                            G4double hinitial = 0 ) override;
0075       // Integrates ODE from current s (s=s0) to s=s0+h with accuracy eps.
0076       // On output track is replaced by value at end of interval.
0077       // The concept is similar to the odeint routine from NRC p.721-722.
0078
0079     G4bool QuickAdvance(      G4FieldTrack& fieldTrack,
0080                         const G4double dydx[],
0081                               G4double hstep,
0082                               G4double& dchord_step,
0083                               G4double& dyerr) override;
0084       // QuickAdvance just tries one Step - it does not ensure accuracy.
0085
0086     void SetVerboseLevel(G4int newLevel) override;
0087     G4int GetVerboseLevel() const override;
0088
0089     void  StreamInfo( std::ostream& os ) const override;
0090      // Write out the parameters / state of the driver
0091
0092     // Accessors
0093     //
0094     G4double GetMinimumStep() const;
0095     void SetMinimumStep(G4double newval);
0096
0097     void OneGoodStep(      G4double  yVar[],  // InOut
0098                      const G4double  dydx[],
0099                            G4double& curveLength,
0100                            G4double  htry,
0101                            G4double  eps,
0102                            G4double& hdid,
0103                            G4double& hnext);
0104       // This takes one Step that is of size htry, or as large
0105       // as possible while satisfying the accuracy criterion of:
0106       //     yerr < eps * |y_end-y_start|
0107
0108     G4double GetSmallestFraction() const;
0109     void SetSmallestFraction(G4double val);
0110
0111   protected:
0112
0113     void IncrementQuickAdvanceCalls();
0114
0115   private:
0116
0117     void CheckStep(const G4ThreeVector& posIn,
0118                    const G4ThreeVector& posOut,
0119                          G4double hdid);
0120
0121     G4double fMinimumStep;
0122       // Minimum Step allowed in a Step (in absolute units)
0123
0124     G4double fSmallestFraction{1e-12};
0125       // Smallest fraction of (existing) curve length - in relative units
0126       // below this fraction the current step will be the last
0127       // Expected range: smaller than 0.1 * epsilon and bigger than 5e-13
0128       // Note: this range is not enforced.
0129
0130     G4int fVerboseLevel;
0131       // Verbosity level for printing (debug, ..)
0132       // Could be varied during tracking - to help identify issues
0133
0134     G4int fNoQuickAvanceCalls{0};
0135     G4int fNoAccurateAdvanceCalls{0};
0136     G4int fNoAccurateAdvanceBadSteps{0};
0137     G4int fNoAccurateAdvanceGoodSteps{0};
0138
0139     using Base = G4RKIntegrationDriver<T>;
0140     using ChordFinderDelegate = G4ChordFinderDelegate<G4IntegrationDriver<T>>;
0141 };
0142
0143 #include "G4IntegrationDriver.icc"
0144
0145 #endif