G4MagIntegratorDriver.hh

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//
// $Id: G4MagIntegratorDriver.hh 109569 2018-05-02 07:08:33Z gcosmo $
//
//
// class G4MagInt_Driver
//
// Class description:
//
// Provides a driver that talks to the Integrator Stepper, and insures that 
// the error is within acceptable bounds.

// History:
// - Created. J.Apostolakis.
// --------------------------------------------------------------------

#ifndef G4MagInt_Driver_Def
#define G4MagInt_Driver_Def

#include "G4VIntegrationDriver.hh"
#include "G4MagIntegratorStepper.hh"

class G4MagInt_Driver : public G4VIntegrationDriver
{
public:  // with description

    G4MagInt_Driver(G4double hminimum,
                    G4MagIntegratorStepper* pItsStepper,
                    G4int numberOfComponents = 6,
                    G4int statisticsVerbosity = 1);
    virtual ~G4MagInt_Driver() override;
    // Constructor, destructor.

    G4MagInt_Driver(const G4MagInt_Driver&) = delete;
    G4MagInt_Driver& operator=(const G4MagInt_Driver&) = delete;
    // deleted Private copy constructor and assignment operator.

    virtual G4bool AccurateAdvance(G4FieldTrack& y_current,
                                   G4double hstep,
                                   G4double eps,            // Requested y_err/hstep
                                   G4double hinitial = 0.0) override;  // Suggested 1st interval
    // Above drivers for integrator (Runge-Kutta) with stepsize control.
    // Integrates ODE starting values y_current
    // from current s (s=s0) to s=s0+h with accuracy eps.
    // On output ystart is replaced by value at end of interval.
    // The concept is similar to the odeint routine from NRC p.721-722.

    virtual G4bool QuickAdvance(G4FieldTrack& y_val,      // INOUT
                                const G4double dydx[],
                                G4double hstep,       // IN
                                G4double& dchord_step,
                                G4double& dyerr) override;
    // QuickAdvance just tries one Step - it does not ensure accuracy.

    G4bool QuickAdvance(G4FieldTrack& y_posvel,        // INOUT
                        const G4double dydx[],
                        G4double hstep,           // IN
                        G4double& dchord_step,
                        G4double& dyerr_pos_sq,
                        G4double& dyerr_mom_rel_sq ) ;
    // New QuickAdvance that also just tries one Step
    //    (so also does not ensure accuracy)
    //    but does return the errors in  position and
    //        momentum (normalised: Delta_Integration(p^2)/(p^2) )

    inline G4double GetHmin() const;
    inline G4double Hmin() const;     // Obsolete
    inline G4double GetSafety() const;
    inline G4double GetPshrnk() const;
    inline G4double GetPgrow() const;
    inline G4double GetErrcon() const;
    virtual void GetDerivatives(const G4FieldTrack &y_curr,     // const, INput
                                G4double dydx[]) const override;      //       OUTput
    // Accessors.

    virtual G4EquationOfMotion* GetEquationOfMotion() override;
    virtual void SetEquationOfMotion(G4EquationOfMotion* equation) override;
   
    virtual void RenewStepperAndAdjust(G4MagIntegratorStepper *pItsStepper) override;
    // Sets a new stepper pItsStepper for this driver. Then it calls
    // ReSetParameters to reset its parameters accordingly.

    inline void ReSetParameters(G4double new_safety= 0.9 );
    //  i) sets the exponents (pgrow & pshrnk),
    //     using the current Stepper's order,
    // ii) sets the safety
    // ii) calculates "errcon" according to the above values.

    inline void SetSafety(G4double valS);
    inline void SetPshrnk(G4double valPs);
    inline void SetPgrow (G4double valPg);
    inline void SetErrcon(G4double valEc);
    // When setting safety or pgrow, errcon will be set to a
    // compatible value.

    inline G4double ComputeAndSetErrcon();

    virtual const G4MagIntegratorStepper* GetStepper() const override;
    virtual       G4MagIntegratorStepper* GetStepper() override;

    void OneGoodStep(G4double  ystart[], // Like old RKF45step()
                     const G4double  dydx[],
                     G4double& x,
                     G4double htry,
                     G4double  eps,      //  memb variables ?
                     G4double& hdid,
                      G4double& hnext ) ;
    // This takes one Step that is as large as possible while
    // satisfying the accuracy criterion of:
    // yerr < eps * |y_end-y_start|

    virtual G4double ComputeNewStepSize(G4double errMaxNorm,    // normalised error
                                        G4double hstepCurrent) override; // current step size
    // Taking the last step's normalised error, calculate
    // a step size for the next step.
    // Do not limit the next step's size within a factor of the
    // current one.

    G4double ComputeNewStepSize_WithinLimits(G4double  errMaxNorm,    // normalised error
                                             G4double  hstepCurrent); // current step size
    // Taking the last step's normalised error, calculate
    // a step size for the next step.
    // Limit the next step's size within a range around the current one.

    inline G4int GetMaxNoSteps() const;
    inline void SetMaxNoSteps( G4int val);
    //  Modify and Get the Maximum number of Steps that can be
    //   taken for the integration of a single segment -
    //   (ie a single call to AccurateAdvance).

public:  // without description

    inline void SetHmin(G4double newval);
    virtual void SetVerboseLevel(G4int newLevel) override;
    virtual G4int GetVerboseLevel() const override;

    inline G4double GetSmallestFraction() const;
    void SetSmallestFraction( G4double val );

protected:  // without description
    void WarnSmallStepSize(G4double hnext, G4double hstep,
                           G4double h, G4double xDone,
                           G4int noSteps);

    void WarnTooManyStep(G4double x1start, G4double x2end, G4double xCurrent);
    void WarnEndPointTooFar(G4double endPointDist,
                            G4double hStepSize ,
                            G4double epsilonRelative,
                            G4int debugFlag);
    //  Issue warnings for undesirable situations

    void PrintStatus(const G4double* StartArr,
                     G4double xstart,
                     const G4double* CurrentArr,
                     G4double xcurrent,
                     G4double requestStep,
                     G4int subStepNo);
    void PrintStatus(const G4FieldTrack& StartFT,
                     const G4FieldTrack& CurrentFT,
                     G4double requestStep,
                     G4int subStepNo);
     void PrintStat_Aux(const G4FieldTrack& aFieldTrack,
                        G4double requestStep,
                        G4double actualStep,
                        G4int subStepNo,
                        G4double subStepSize,
                        G4double dotVelocities);
    //  Verbose output for debugging

    void PrintStatisticsReport();
    //  Report on the number of steps, maximum errors etc.

#ifdef QUICK_ADV_TWO
     G4bool QuickAdvance(       G4double     yarrin[],     // In
                         const G4double     dydx[],  
                               G4double     hstep,        
                               G4double     yarrout[],    // Out
                               G4double&    dchord_step,  // Out
                               G4double&    dyerr );      // in length
#endif

private:
     // ---------------------------------------------------------------
     //  INVARIANTS 

    G4double  fMinimumStep;
    // Minimum Step allowed in a Step (in absolute units)
    G4double  fSmallestFraction;      //   Expected range 1e-12 to 5e-15;
    // Smallest fraction of (existing) curve length - in relative units
    //  below this fraction the current step will be the last

    const G4int  fNoIntegrationVariables;  // Number of Variables in integration
    const G4int  fMinNoVars;               // Minimum number for FieldTrack
    const G4int  fNoVars;                  // Full number of variable

    G4int   fMaxNoSteps;
    G4int   fMaxStepBase;

    G4double safety;
    G4double pshrnk;   //  exponent for shrinking
    G4double pgrow;    //  exponent for growth
    G4double errcon;
    // Parameters used to grow and shrink trial stepsize.

    G4int    fStatisticsVerboseLevel;

    // ---------------------------------------------------------------
    // DEPENDENT Objects
    G4MagIntegratorStepper *pIntStepper;

    // ---------------------------------------------------------------
    //  STATE

    unsigned long fNoTotalSteps, fNoBadSteps, fNoSmallSteps, fNoInitialSmallSteps;
    unsigned long fNoCalls;
    G4double fDyerr_max, fDyerr_mx2;
    G4double fDyerrPos_smTot, fDyerrPos_lgTot, fDyerrVel_lgTot;
    G4double fSumH_sm, fSumH_lg;
    // Step Statistics

    G4int  fVerboseLevel;   // Verbosity level for printing (debug, ..)
    // Could be varied during tracking - to help identify issues

};

#include "G4MagIntegratorDriver.icc"

#endif /* G4MagInt_Driver_Def */