include/Geant4/G4VIntegrationDriver.hh

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0025 //
0026 // G4VIntegrationDriver
0027 //
0028 // Class description:
0029 //
0030 // Abstract base class for 'driver' classes which are responsible for
0031 // undertaking integration of an state given an equation of motion and
0032 // within acceptable error bound(s).
0033 //
0034 // Different integration methods are meant to be provided via this
0035 // common interface, and can span the original type (explicit Runge Kutta
0036 // methods), enhanced RK methods and alternatives such as the
0037 // Bulirsch-Stoer and multi-step methods.
0038 //
0039 // The drivers' key mission is to insure that the error is below set values.
0040
0041 // Author: Dmitry Sorokin (CERN, Google Summer of Code 2017), 20.10.2017
0042 // Supervision: John Apostolakis (CERN)
0043 // --------------------------------------------------------------------
0044 #ifndef G4VINTEGRATION_DRIVER_HH
0045 #define G4VINTEGRATION_DRIVER_HH
0046
0047 #include "G4Types.hh"
0048 #include "G4FieldTrack.hh"
0049 #include "G4EquationOfMotion.hh"
0050
0051 class G4MagIntegratorStepper;
0052
0053 class G4VIntegrationDriver
0054 {
0055   public:
0056
0057     /**
0058      * Default Destructor.
0059      */
0060     virtual ~G4VIntegrationDriver() = default;
0061
0062     /**
0063      * Computes the step to take, based on chord limits.
0064      *  @param[in,out] track The current track in field.
0065      *  @param[in] hstep Proposed step length.
0066      *  @param[in] eps Requested accuracy, y_err/hstep.
0067      *  @param[in] chordDistance Maximum sagitta distance.
0068      *  @returns The length of step taken.
0069      */
0070     virtual G4double AdvanceChordLimited(G4FieldTrack& track,
0071                                          G4double hstep,
0072                                          G4double eps,
0073                                          G4double chordDistance) = 0;
0074
0075     /**
0076      * Advances integration accurately by relative accuracy better than 'eps'.
0077      * On output the track is replaced by the value at the end of interval.
0078      *  @param[in,out] track The current track in field.
0079      *  @param[in] hstep Proposed step length.
0080      *  @param[in] eps Requested accuracy, y_err/hstep.
0081      *  @param[in] hinitial Initial minimum integration step.
0082      *  @returns true if integration succeeds.
0083      */
0084     virtual G4bool AccurateAdvance(G4FieldTrack& track,
0085                                    G4double hstep,
0086                                    G4double eps, // Requested y_err/hstep
0087                                    G4double hinitial = 0 ) = 0;
0088
0089     /**
0090      * Setter and getter for the equation of motion.
0091      */
0092     virtual void SetEquationOfMotion(G4EquationOfMotion* equation) = 0;
0093     virtual G4EquationOfMotion* GetEquationOfMotion() = 0;
0094
0095     /**
0096      * Method for compatibility -- relevant only for G4MagIntegratorDriver.
0097      */
0098     virtual void RenewStepperAndAdjust(G4MagIntegratorStepper* pItsStepper);
0099
0100     /**
0101      * Setter and getter for verbosity.
0102      */
0103     virtual void SetVerboseLevel(G4int level) = 0;
0104     virtual G4int GetVerboseLevel() const = 0;
0105
0106     /**
0107      * Dispatch interface method for computing step.
0108      */
0109     virtual void OnComputeStep(const G4FieldTrack* /*track*/ = nullptr) = 0;
0110
0111     /**
0112      * Dispatch interface method for initialisation/reset of driver.
0113      */
0114     virtual void OnStartTracking() = 0;
0115
0116     /**
0117      * Whether the driver implements re-integration:
0118      * Does this driver *Recalculate* when AccurateAdvance() is called ?
0119      */
0120     virtual G4bool DoesReIntegrate() const = 0;
0121
0122     /**
0123      * Writes out to stream the parameters/state of the driver.
0124      */
0125     virtual void StreamInfo( std::ostream& os ) const = 0;
0126
0127     /**
0128      * Streaming operator.
0129      */
0130     friend std::ostream& operator<<( std::ostream& os, const G4VIntegrationDriver& id);
0131
0132     // ------------------------------------------------------------------------
0133
0134     //[[deprecated("will be removed")]]
0135     virtual G4bool QuickAdvance(G4FieldTrack& /*track*/,   // INOUT
0136                                 const G4double /*dydx*/[],
0137                                 G4double /*hstep*/,
0138                                 G4double& /*dchord_step*/,
0139                                 G4double& /*dyerr*/) { return false; }
0140
0141     //[[deprecated("will be removed")]]
0142     virtual void GetDerivatives(const G4FieldTrack& track,
0143                                 G4double dydx[]) const = 0;
0144
0145     //[[deprecated("will be removed")]]
0146     virtual void GetDerivatives(const G4FieldTrack& track,
0147                                 G4double dydx[],
0148                                 G4double field[]) const = 0;
0149
0150     //[[deprecated("use GetEquationOfMotion() instead of GetStepper()->GetEquationOfMotion()")]]
0151     virtual const G4MagIntegratorStepper* GetStepper() const = 0;
0152     virtual G4MagIntegratorStepper* GetStepper() = 0;
0153
0154     //[[deprecated("will be removed")]]
0155     virtual G4double ComputeNewStepSize(G4double errMaxNorm, // normalised error
0156                                         G4double hstepCurrent) = 0;
0157       // Taking the last step's normalised error, calculate
0158       // a step size for the next step.
0159       // - Can limit the next step's size within a factor of the current one.
0160
0161   protected:
0162
0163     static constexpr G4double max_stepping_increase = 5;
0164     static constexpr G4double max_stepping_decrease = 0.1;
0165 };
0166
0167 #endif