Gabriele Cosmo
270 lines
10 KiB
C++
270 lines
10 KiB
C++
// ********************************************************************
|
|
// * License and Disclaimer *
|
|
// * *
|
|
// * The Geant4 software is copyright of the Copyright Holders of *
|
|
// * the Geant4 Collaboration. It is provided under the terms and *
|
|
// * conditions of the Geant4 Software License, included in the file *
|
|
// * LICENSE and available at http://cern.ch/geant4/license . These *
|
|
// * include a list of copyright holders. *
|
|
// * *
|
|
// * Neither the authors of this software system, nor their employing *
|
|
// * institutes,nor the agencies providing financial support for this *
|
|
// * work make any representation or warranty, express or implied, *
|
|
// * regarding this software system or assume any liability for its *
|
|
// * use. Please see the license in the file LICENSE and URL above *
|
|
// * for the full disclaimer and the limitation of liability. *
|
|
// * *
|
|
// * This code implementation is the result of the scientific and *
|
|
// * technical work of the GEANT4 collaboration. *
|
|
// * By using, copying, modifying or distributing the software (or *
|
|
// * any work based on the software) you agree to acknowledge its *
|
|
// * use in resulting scientific publications, and indicate your *
|
|
// * acceptance of all terms of the Geant4 Software license. *
|
|
// ********************************************************************
|
|
//
|
|
// G4BorisDriver
|
|
//
|
|
// Class description:
|
|
//
|
|
// G4BorisDriver is a driver class using the second order Boris
|
|
// method to integrate the equation of motion.
|
|
|
|
// Author: Divyansh Tiwari (CERN, Google Summer of Code 2022), 05.11.2022
|
|
// Supervision: John Apostolakis (CERN), Renee Fatemi, Soon Yung Jun (FNAL)
|
|
// --------------------------------------------------------------------
|
|
#ifndef G4BORIS_DRIVER_HH
|
|
#define G4BORIS_DRIVER_HH
|
|
|
|
#include "G4VIntegrationDriver.hh"
|
|
#include "G4BorisScheme.hh"
|
|
#include "G4ChordFinderDelegate.hh"
|
|
|
|
/**
|
|
* @brief G4BorisDriver is a driver class using the second order Boris
|
|
* method to integrate the equation of motion.
|
|
*/
|
|
|
|
class G4BorisDriver : public G4VIntegrationDriver,
|
|
public G4ChordFinderDelegate<G4BorisDriver>
|
|
{
|
|
public:
|
|
|
|
/**
|
|
* Constructor for G4BorisDriver.
|
|
* @param[in] hminimum The minumum allowed step.
|
|
* @param[in] Boris Pointer to the Boris motion algorithm.
|
|
* @param[in] numberOfComponents The number of integration variables.
|
|
* @param[in] verbosity Flag for verbosity.
|
|
*/
|
|
G4BorisDriver( G4double hminimum,
|
|
G4BorisScheme* Boris,
|
|
G4int numberOfComponents = 6,
|
|
G4bool verbosity = false);
|
|
|
|
/**
|
|
* Default Destructor.
|
|
*/
|
|
~G4BorisDriver() override = default;
|
|
|
|
/**
|
|
* Copy constructor and assignment operator not allowed.
|
|
*/
|
|
G4BorisDriver(const G4BorisDriver&) = delete;
|
|
G4BorisDriver& operator=(const G4BorisDriver&) = delete;
|
|
|
|
// 1. Core methods that advance the integration
|
|
|
|
/**
|
|
* Advances integration accurately by relative accuracy better than 'eps'.
|
|
* @param[in,out] track The current track in field.
|
|
* @param[in] stepLen Proposed step length.
|
|
* @param[in] epsilon Requested accuracy, y_err/hstep.
|
|
* @param[in] beginStep Initial minimum integration step.
|
|
* @returns true if integration succeeds.
|
|
*/
|
|
G4bool AccurateAdvance(G4FieldTrack& track,
|
|
G4double stepLen,
|
|
G4double eps,
|
|
G4double beginStep = 0) override;
|
|
|
|
/**
|
|
* Attempts one integration step, and returns estimated error 'dyerr'.
|
|
* It does not ensure accuracy.
|
|
* @param[in,out] y_val The current track in field.
|
|
* @param[in] dydx dydx array.
|
|
* @param[in] hstep Proposed step length.
|
|
* @param[out] missDist Estimated sagitta distance.
|
|
* @param[out] dyerr Estimated error.
|
|
* @returns true if integration succeeds.
|
|
*/
|
|
G4bool QuickAdvance(G4FieldTrack& y_val, // In/Out
|
|
const G4double dydx[],
|
|
G4double hstep,
|
|
G4double& missDist, // Out: estimated sagitta
|
|
G4double& dyerr) override;
|
|
/**
|
|
* Takes one Step that is as large as possible while satisfying the
|
|
* accuracy criterion.
|
|
* @param[in,out] yCurrentState The current track state, y.
|
|
* @param[in,out] curveLength Step start, x.
|
|
* @param[in] htry Step to attempt.
|
|
* @param[in] epsilon_rel The relative accuracy.
|
|
* @param[in] restMass Mass value for computing velocity.
|
|
* @param[in] charge Charge value for computing momentum.
|
|
* @param[out] hdid Step achieved.
|
|
* @param[out] hnext Proposed next step.
|
|
* @returns true if integration succeeds.
|
|
*/
|
|
void OneGoodStep(G4double yCurrentState[], // In/Out: state ('y')
|
|
G4double& curveLength, // In/Out: 'x'
|
|
G4double htry, // step to attempt
|
|
G4double epsilon_rel, // relative accuracy
|
|
G4double restMass,
|
|
G4double charge,
|
|
G4double& hdid, // Out: step achieved
|
|
G4double& hnext); // Out: proposed next step
|
|
|
|
// 2. Methods needed to co-work with G4ChordFinder
|
|
|
|
/**
|
|
* Computes the step to take, based on chord limits.
|
|
* @param[in,out] track The current track in field.
|
|
* @param[in] hstep Proposed step length.
|
|
* @param[in] eps Requested accuracy, y_err/hstep.
|
|
* @param[in] chordDistance Maximum sagitta distance.
|
|
* @returns The length of step taken.
|
|
*/
|
|
inline G4double AdvanceChordLimited(G4FieldTrack& track,
|
|
G4double hstep,
|
|
G4double eps,
|
|
G4double chordDistance) override;
|
|
/**
|
|
* Dispatch interface method for initialisation/reset of driver.
|
|
*/
|
|
inline void OnStartTracking() override;
|
|
|
|
/**
|
|
* Dispatch interface method for computing step. Does nothing here.
|
|
*/
|
|
inline void OnComputeStep(const G4FieldTrack*) override;
|
|
|
|
// 3. Does the method redo integrations when called to obtain values for
|
|
// internal, smaller intervals? (when needed to identify an intersection)
|
|
|
|
/**
|
|
* The driver implements re-integration. Returns true.
|
|
* It would be false if it just used interpolation to provide a result.
|
|
*/
|
|
inline G4bool DoesReIntegrate() const override;
|
|
|
|
// 4. Relevant for calculating a new step size to achieve required accuracy
|
|
|
|
/**
|
|
* Computes a step size for the next step, taking the last step's
|
|
* normalised error 'errMaxNorm'.
|
|
* @param[in] errMaxNorm The normalised error on last step.
|
|
* @param[in] hstepCurrent The current proposed step.
|
|
* @returns The step size for the next step.
|
|
*/
|
|
inline G4double ComputeNewStepSize(G4double errMaxNorm,
|
|
G4double hstepCurrent) override;
|
|
|
|
/**
|
|
* Methods to calculate the next step size given the square of the
|
|
* relative error.
|
|
*/
|
|
G4double ShrinkStepSize2(G4double h, G4double error2) const;
|
|
G4double GrowStepSize2(G4double h, G4double error2) const;
|
|
|
|
// 5. Auxiliary Methods ...
|
|
|
|
/**
|
|
* Getters for derivatives.
|
|
*/
|
|
void GetDerivatives( const G4FieldTrack& track,
|
|
G4double dydx[] ) const override;
|
|
void GetDerivatives( const G4FieldTrack& track,
|
|
G4double dydx[],
|
|
G4double field[] ) const override;
|
|
|
|
/**
|
|
* Setter and getter for verbosity.
|
|
*/
|
|
inline void SetVerboseLevel(G4int level) override;
|
|
inline G4int GetVerboseLevel() const override;
|
|
|
|
/**
|
|
* Getters for the equation of motion.
|
|
*/
|
|
inline G4EquationOfMotion* GetEquationOfMotion() override;
|
|
inline const G4EquationOfMotion* GetEquationOfMotion() const;
|
|
|
|
/**
|
|
* Setter for the equation of motion. Issues an exception, as not
|
|
* foreseen to change equation of motion for the Boris stepper.
|
|
*/
|
|
void SetEquationOfMotion(G4EquationOfMotion* equation) override;
|
|
|
|
/**
|
|
* Writes out to stream the parameters/state of the driver.
|
|
*/
|
|
void StreamInfo( std::ostream& os ) const override;
|
|
|
|
/**
|
|
* Accessors for stepper. Not relevant for Boris and other non-RK methods.
|
|
*/
|
|
inline const G4MagIntegratorStepper* GetStepper() const override;
|
|
inline G4MagIntegratorStepper* GetStepper() override;
|
|
|
|
private:
|
|
|
|
inline G4int GetNumberOfVariables() const;
|
|
|
|
inline void CheckStep(const G4ThreeVector& posIn,
|
|
const G4ThreeVector& posOut,
|
|
G4double hdid) const;
|
|
|
|
private:
|
|
|
|
// INVARIANTS -- remain unchanged during tracking / integration
|
|
// Parameters
|
|
G4double fMinimumStep;
|
|
G4bool fVerbosity;
|
|
|
|
// State -- The core stepping algorithm
|
|
G4BorisScheme* boris;
|
|
|
|
// STATE -- intermediate state (to avoid creation / churn )
|
|
G4double yIn[G4FieldTrack::ncompSVEC],
|
|
yMid[G4FieldTrack::ncompSVEC],
|
|
yOut[G4FieldTrack::ncompSVEC],
|
|
yError[G4FieldTrack::ncompSVEC];
|
|
|
|
G4double yCurrent[G4FieldTrack::ncompSVEC];
|
|
|
|
// - Unused 2022.11.03:
|
|
// G4double derivs[2][6][G4FieldTrack::ncompSVEC];
|
|
// const G4int interval_sequence[2];
|
|
|
|
// INVARIANTS -- Parameters for ensuring that one call has finite number of integration steps
|
|
static constexpr G4int fMaxNoSteps = 300;
|
|
static constexpr G4double fSmallestFraction= 1e-12; // To avoid FP underflow ! ( 1.e-6 for single prec)
|
|
|
|
static constexpr G4int fIntegratorOrder= 2; // 2nd order method -- needed for error control
|
|
static constexpr G4double fSafetyFactor = 0.9; //
|
|
|
|
static constexpr G4double fMaxSteppingIncrease= 10.0; // Increase no more than 10x
|
|
static constexpr G4double fMaxSteppingDecrease= 0.1; // Reduce no more than 10x
|
|
static constexpr G4double fPowerShrink = -1.0 / fIntegratorOrder;
|
|
static constexpr G4double fPowerGrow = -1.0 / (1.0 + fIntegratorOrder);
|
|
|
|
static const G4double fErrorConstraintShrink;
|
|
static const G4double fErrorConstraintGrow;
|
|
|
|
using ChordFinderDelegate = G4ChordFinderDelegate<G4BorisDriver>;
|
|
};
|
|
|
|
#include "G4BorisDriver.icc"
|
|
|
|
#endif
|