Gabriele Cosmo
141 lines
5.1 KiB
C++
141 lines
5.1 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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// G4RKG3_Stepper
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//
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// Class description:
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//
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// Runga-Kutta integrator stepper from Geant-3.
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// Authors: John Apostolakis & Vladimir Grichine (CERN), 30.01.1997
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// -------------------------------------------------------------------
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#ifndef G4RKG3_STEPPER_HH
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#define G4RKG3_STEPPER_HH
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#include "G4Types.hh"
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#include "G4MagIntegratorStepper.hh"
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#include "G4ThreeVector.hh"
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class G4Mag_EqRhs;
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/**
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* @brief G4RKG3_Stepper implements a Runga-Kutta integrator stepper
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* used in Geant-3.
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*/
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class G4RKG3_Stepper : public G4MagIntegratorStepper
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{
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public:
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/**
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* Constructor for G4RKG3_Stepper.
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* @param[in] EqRhs Pointer to the provided equation of motion.
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*/
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G4RKG3_Stepper(G4Mag_EqRhs* EqRhs);
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/**
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* Default Destructor.
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*/
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~G4RKG3_Stepper() override = default;
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/**
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* Copy constructor and assignment operator not allowed.
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*/
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G4RKG3_Stepper(const G4RKG3_Stepper&) = delete;
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G4RKG3_Stepper& operator= (const G4RKG3_Stepper&) = delete;
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/**
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* The stepper for the Runge Kutta integration.
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* Method provided, even if less efficient.
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* The stepsize is fixed, with the step size given by 'h'.
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* Integrates ODE starting values yInput[0 to 6].
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* Outputs yOut[] and its estimated error yErr[].
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* @param[in] yIn Starting values array of integration variables.
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* @param[in] dydx Derivatives array.
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* @param[in] h The given step size.
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* @param[out] yOut Integration output.
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* @param[out] yErr The estimated error.
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*/
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void Stepper( const G4double yIn[],
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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[] ) 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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* Integrator of Runge-Kutta Stepper from Geant-3 with only two field
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* evaluation per Step. It is used in propagating the initial Step
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* by small substeps after solution error and delta geometry
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* considerations. B[3] is magnetic field which is passed from substep
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* to substep.
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*/
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void StepNoErr( const G4double tIn[8],
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const G4double dydx[6],
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G4double Step,
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G4double tOut[8],
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G4double B[3] );
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/**
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* Integrator for Runge-Kutta from Geant-3 with evaluation of error in
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* solution and delta geometry based on naive similarity with the case
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* of uniform magnetic field.
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* B1[3] is in input and is the first magnetic field values
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* B2[3] is the output and is the final magnetic field values.
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*/
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void StepWithEst( const G4double tIn[8],
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const G4double dydx[6],
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G4double Step,
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G4double tOut[8],
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G4double& alpha2,
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G4double& beta2,
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const G4double B1[3],
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G4double B2[3] );
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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 { return 4; }
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/**
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* Returns the stepper type-ID, "kRKG3Stepper".
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*/
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inline G4StepperType StepperType() const override { return kRKG3Stepper; }
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private:
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G4ThreeVector fyInitial,
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fyMidPoint,
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fyFinal;
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G4ThreeVector fpInitial;
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G4ThreeVector BfldIn;
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G4double hStep = 0.0;
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};
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#endif
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