Gabriele Cosmo
125 lines
4.8 KiB
C++
125 lines
4.8 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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// G4DormandPrinceRK78
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//
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// Class description:
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//
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// Dormand-Prince 8(7)13M non-FSAL RK method, a 13 stage embedded
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// explicit Runge-Kutta method, using a pair of 7th and 8th order formulae.
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//
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// Paper proposing this RK scheme:
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// P.J. Prince, J.R. Dormand, "High order embedded Runge-Kutta formulae",
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// Journal of Computational and Applied Mathematics, Volume 7, Issue 1, 1981,
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// Pages 67-75, ISSN 0377-0427, DOI: 10.1016/0771-050X(81)90010-3
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// Author: Somnath Banerjee (CERN, Google Summer of Code 2015), 28.06.2015
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// Supervision: John Apostolakis (CERN)
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// --------------------------------------------------------------------
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#ifndef G4DORMAND_PRINCE_RK78_HH
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#define G4DORMAND_PRINCE_RK78_HH
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#include "G4MagIntegratorStepper.hh"
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/**
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* @brief G4DormandPrinceRK78 implements the Dormand-Prince 8(7)13M non-FSAL
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* Runge-Kutta method, a 13 stage embedded explicit Runge-Kutta method, using
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* a pair of 7th and 8th order formulae.
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*/
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class G4DormandPrinceRK78 : public G4MagIntegratorStepper
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{
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public:
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/**
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* Constructor for G4DormandPrince745.
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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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* @param[in] primary Flag for initialisation of the auxiliary stepper.
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*/
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G4DormandPrinceRK78(G4EquationOfMotion* EqRhs,
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G4int numberOfVariables = 6,
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G4bool primary = true);
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/**
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* Destructor.
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*/
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~G4DormandPrinceRK78() override;
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/**
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* Copy constructor and assignment operator not allowed.
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*/
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G4DormandPrinceRK78(const G4DormandPrinceRK78&) = delete;
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G4DormandPrinceRK78& operator=(const G4DormandPrinceRK78&) = 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 '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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* @param[in] y 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 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[]) 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 order, 7, of integration.
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*/
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inline G4int IntegratorOrder() const override { return 7; }
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/**
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* Returns the stepper type-ID, "kDormandPrinceRK78".
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*/
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inline G4StepperType StepperType() const override { return kDormandPrinceRK78; }
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private :
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G4double *ak2, *ak3, *ak4, *ak5, *ak6, *ak7, *ak8,
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*ak9, *ak10, *ak11, *ak12, *ak13,
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*yTemp, *yIn;
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G4double fLastStepLength = -1.0;
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/** For DistChord() calculations. */
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G4double *fLastInitialVector, *fLastFinalVector,
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*fLastDyDx, *fMidVector, *fMidError;
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G4DormandPrinceRK78* fAuxStepper = nullptr;
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};
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#endif
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