Gabriele Cosmo
144 lines
5.8 KiB
C++
144 lines
5.8 KiB
C++
//
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// ********************************************************************
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// * License and Disclaimer *
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// * *
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// * The Geant4 software is copyright of the Copyright Holders of *
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// * the Geant4 Collaboration. It is provided under the terms and *
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// * conditions of the Geant4 Software License, included in the file *
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// * LICENSE and available at http://cern.ch/geant4/license . These *
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// * include a list of copyright holders. *
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// * *
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// * Neither the authors of this software system, nor their employing *
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// * institutes,nor the agencies providing financial support for this *
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// * work make any representation or warranty, express or implied, *
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// * regarding this software system or assume any liability for its *
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// * use. Please see the license in the file LICENSE and URL above *
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// * for the full disclaimer and the limitation of liability. *
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// * *
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// * This code implementation is the result of the scientific and *
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// * technical work of the GEANT4 collaboration. *
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// * By using, copying, modifying or distributing the software (or *
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// * any work based on the software) you agree to acknowledge its *
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// * use in resulting scientific publications, and indicate your *
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// * acceptance of all terms of the Geant4 Software license. *
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// ********************************************************************
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//
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//
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// class G4VFSALIntegrationStepper
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//
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// Class description:
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// Class similar to G4VMagIntegratorStepper, for steppers which
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// estimate the value of the derivative at the projected endpoint
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// of integration - at each successful step.
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// This ability is known as 'First Same As Last' (FSAL). It
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// reduces the number of required calls to the equation's
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// RightHandSide method, and, as such the number of calls to the
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// (potentially expensive) field evaluation methods.
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//
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// Based on G4VMagIntegratorStepper
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//
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// Design/first implementation: Somnath Banerjee, May-Aug 2015,
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// Work supported by the Google Summer of Code 2015.
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// Supervision/improvement: John Apostolakis 2015-2016
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// --------------------------------------------------------------------
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#ifndef FSAL_MAGIntegrator_STEPPER
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#define FSAL_MAGIntegrator_STEPPER
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#include "G4Types.hh"
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#include "G4EquationOfMotion.hh"
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class G4VFSALIntegrationStepper
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{
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public: // with description
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G4VFSALIntegrationStepper (G4EquationOfMotion* Equation,
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G4int numIntegrationVariables,
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G4int numStateVariables=12);
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virtual ~G4VFSALIntegrationStepper() = default;
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// Constructor and destructor. No actions.
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virtual void Stepper( const G4double y[],
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const G4double dydx[],
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G4double h,
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G4double yout[],
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G4double yerr[],
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G4double lastDydx[]) = 0 ;
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// The stepper for the Runge Kutta integration.
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// The stepsize is fixed, with the Step size given by h.
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// Integrates ODE starting values y[0 to 6].
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// Outputs yout[] and its estimated error yerr[].
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virtual G4double DistChord() const = 0;
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// Estimate the maximum distance of a chord from the true path
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// over the segment last integrated.
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// virtual G4bool isFSAL() const = 0;
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// //Return true if the stepper uses FSAL (First Same As Last)
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// G4double *getLastDydx() {return 0;}
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inline void NormaliseTangentVector( G4double vec[6] );
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// Simple utility function to (re)normalise 'unit velocity' vector.
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inline void NormalisePolarizationVector( G4double vec[12] );
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// Simple utility function to (re)normalise 'unit spin' vector.
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void RightHandSide( const double y[], double dydx[] );
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// Utility method to supply the standard Evaluation of the
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// Right Hand side of the associated equation.
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inline G4int GetNumberOfVariables() const;
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// Get the number of variables that the stepper will integrate over.
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// void SetNumberOfVariables(G4int newNo); // Dangerous & obsolete ...
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inline G4int GetNumberOfStateVariables() const;
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// Get the number of variables of state variables (>= above, integration)
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virtual G4int IntegratorOrder() const = 0;
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// Returns the order of the integrator
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// i.e. its error behaviour is of the order O(h^order).
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inline G4EquationOfMotion *GetEquationOfMotion();
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// As some steppers (eg RKG3) require other methods of Eq_Rhs
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// this function allows for access to them.
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inline void SetEquationOfMotion(G4EquationOfMotion* newEquation);
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//--- --- For DEBUG --- ---
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inline G4int GetfNoRHSCalls(){
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return fNoRHSCalls;
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}
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void increasefNORHSCalls();
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inline void ResetfNORHSCalls(){
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fNoRHSCalls = 0;
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}
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//--- --- ///////// --- ---
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private:
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G4VFSALIntegrationStepper(const G4VFSALIntegrationStepper&);
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G4VFSALIntegrationStepper& operator=(const G4VFSALIntegrationStepper&);
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// Private copy constructor and assignment operator.
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private:
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G4EquationOfMotion *fEquation_Rhs;
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const G4int fNoIntegrationVariables; // Number of Variables in integration
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const G4int fNoStateVariables; // Number required for FieldTrack
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//--- --- For DEBUG --- ---
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G4int fNoRHSCalls;
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//--- --- ///////// --- ---
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// const G4int fNumberOfVariables;
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};
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#include "G4VFSALIntegrationStepper.icc"
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#endif /* G4VFSALIntegrationStepper */
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