Gabriele Cosmo
139 lines
4.9 KiB
C++
139 lines
4.9 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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// G4NystromRK4
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//
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// Class description:
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//
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// Integrates the equations of the motion of a particle in a magnetic field
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// using 4th Runge-Kutta-Nystrom method with errors estimation
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// (ATL-SOFT-PUB-2009-01)
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// Current form can be used only for 'pure' magnetic field.
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// Notes: 1) field must be time-independent.
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// 2) time is not integrated
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// Author: Igor Gavrilenko (CERN), 15.05.2009 (as G4AtlasRK4)
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// Adaptations: John Apostolakis (CERN), 05.11.2009
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// -------------------------------------------------------------------
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#ifndef G4NYSTROMRK4_HH
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#define G4NYSTROMRK4_HH
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#include "G4MagIntegratorStepper.hh"
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#include "G4Mag_EqRhs.hh"
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#include "G4CachedMagneticField.hh"
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#include "G4ThreeVector.hh"
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#include <memory>
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/**
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* @brief G4NystromRK4 integrates the equations of the motion of a particle
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* in a magnetic field using 4th Runge-Kutta-Nystrom method with errors
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* estimation. The current form can be used only for 'pure' magnetic field.
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*/
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class G4NystromRK4 : public G4MagIntegratorStepper
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{
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public:
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/**
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* Constructor for G4NystromRK4. Can be used only for Magnetic Fields
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* and for 6 variables (x,p).
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* @param[in] EquationMotion Pointer to the provided equation of motion.
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* @param[in] distanceConstField Distance value for constant field.
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*/
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G4NystromRK4(G4Mag_EqRhs* EquationMotion,
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G4double distanceConstField = 0.0);
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/**
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* Default Destructor.
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*/
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~G4NystromRK4() override = default;
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/**
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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 'hstep'.
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* Integrates ODE starting values y[0 to 6].
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* Outputs yOut[] and its estimated error yError[].
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* Provides error via analytical method.
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* @param[in] y Starting values array of integration variables.
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* @param[in] dydx Derivatives array.
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* @param[in] hstep The given step size.
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* @param[out] yOut Integration output.
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* @param[out] yError The estimated error.
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*/
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void Stepper(const G4double y[],
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const G4double dydx[],
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G4double hstep,
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G4double yOut[],
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G4double yError[]) override;
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/**
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* Setter and getter for the distance value for constant field.
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*/
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void SetDistanceForConstantField(G4double length);
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G4double GetDistanceForConstantField() const;
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/**
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* Returns the order, 4, of integration.
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*/
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inline G4int IntegratorOrder() const override;
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/**
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* Returns the distance from chord line.
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*/
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G4double DistChord() const override;
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/**
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* Returns the stepper type-ID, "kNystromRK4".
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*/
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inline G4StepperType StepperType() const override;
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private:
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/**
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* Private accessors for field data.
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*/
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inline void GetFieldValue(const G4double point[4], G4double field[3]);
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inline G4double GetFCof();
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G4CachedMagneticField* GetField();
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const G4CachedMagneticField* GetField() const;
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private:
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G4double fMomentum = 0.0;
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G4double fMomentum2 = 0.0;
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G4double fInverseMomentum = 0.0;
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G4double fCoefficient = 0.0;
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G4ThreeVector fInitialPoint;
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G4ThreeVector fMidPoint;
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G4ThreeVector fEndPoint;
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std::unique_ptr<G4CachedMagneticField> fCachedField;
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};
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#include "G4NystromRK4.icc"
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#endif
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