Gabriele Cosmo
148 lines
5.6 KiB
C++
148 lines
5.6 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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// G4BogackiShampine23
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//
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// Class description:
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//
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// Bogacki-Shampine - 4 - 3(2) non-FSAL implementation
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//
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// An implementation of the embedded RK method from the paper
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// [1] P. Bogacki and L. F. Shampine,
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// "A 3(2) pair of Runge - Kutta formulas"
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// Appl. Math. Lett., vol. 2, no. 4, pp. 321-325, Jan. 1989.
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//
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// This version does not utilise the FSAL property of the method,
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// which would allow the reuse of the last derivative in the next step.
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// (Alternative FSAL implementation created with revised interface)
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// Author: Somnath Banerjee (CERN, Google Summer of Code 2015), 20.05.2015
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// Supervision: John Apostolakis (CERN)
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// --------------------------------------------------------------------
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#ifndef G4BOGACKI_SHAMPINE23_HH
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#define G4BOGACKI_SHAMPINE23_HH
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#include "G4MagIntegratorStepper.hh"
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#include "G4FieldTrack.hh"
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/**
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* @brief G4BogackiShampine23 is an integrator of particle's equation of
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* motion based on the Bogacki-Shampine non-FSAL implementation.
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*/
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class G4BogackiShampine23 : public G4MagIntegratorStepper
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{
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public:
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/**
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* Constructor for G4BogackiShampine23.
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* @param[in] EqRhs Pointer to the provided equation of motion.
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* @param[in] numberOfVariables The number of integration variables.
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*/
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G4BogackiShampine23(G4EquationOfMotion* EqRhs,
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G4int numberOfVariables = 6);
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/**
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* Default Destructor.
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*/
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~G4BogackiShampine23() 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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G4BogackiShampine23(const G4BogackiShampine23&) = delete;
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G4BogackiShampine23& operator = (const G4BogackiShampine23&) = delete;
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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 yInput[0 to 6].
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* Outputs yOutput[] and its estimated error yError[].
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* @param[in] yInput 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] yOutput Integration output.
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* @param[out] yError The estimated error.
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*/
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void Stepper(const G4double yInput[],
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const G4double dydx[],
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G4double hstep,
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G4double yOutput[],
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G4double yError[]) override;
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/**
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* Same as the Stepper() function above, with dydx also in ouput.
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* @param[in] yInput 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] yOutput Integration output.
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* @param[out] yError The estimated error.
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* @param[out] dydxOutput dydx in output.
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*/
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void Stepper(const G4double yInput[],
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const G4double dydx[],
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G4double hstep,
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G4double yOutput[],
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G4double yError[],
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G4double dydxOutput[]);
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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 order, 3, of integration.
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*/
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inline G4int IntegratorOrder() const override { return 3; }
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/**
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* Returns the stepper type-ID, "kBogackiShampine23".
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*/
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inline G4StepperType StepperType() const override { return kBogackiShampine23; }
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private:
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/**
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* Utility method used in Stepper() for computing the actual step.
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*/
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void makeStep(const G4double yInput[],
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const G4double dydx[],
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const G4double hstep,
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G4double yOutput[],
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G4double* dydxOutput = nullptr,
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G4double* yError = nullptr) const;
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private:
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G4double fyIn[G4FieldTrack::ncompSVEC],
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fdydx[G4FieldTrack::ncompSVEC],
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fyOut[G4FieldTrack::ncompSVEC],
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fdydxOut[G4FieldTrack::ncompSVEC];
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G4double fhstep = -1.0;
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};
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#endif
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