Gabriele Cosmo
145 lines
5.4 KiB
C++
145 lines
5.4 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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// G4TsitourasRK45
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//
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// Class description:
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//
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// Tsitouras - 5(4) RK stepper (non-FSAL version)
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// Implements RK tableau from 'Table 1' of:
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// C. Tsitouras, "Runge-Kutta pairs of order 5(4) satisfying only
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// the first column simplifying assumption"
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// Computers & Mathematics with Applications,
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// vol. 62, no. 2, pp. 770-775, 2011.
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// Author: Somnath Banerjee (CERN, Google Summer of Code 2015), 11.06.2015
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// Supervision: John Apostolakis (CERN)
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// --------------------------------------------------------------------
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#ifndef TSITOURAS_RK45_HH
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#define TSITOURAS_RK45_HH
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#include "G4MagIntegratorStepper.hh"
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/**
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* @brief G4TsitourasRK45 is an implementation of the 5(4) Runge-Kutta
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* stepper (non-FSAL version).
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*/
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class G4TsitourasRK45 : public G4MagIntegratorStepper
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{
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public:
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/**
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* Constructor for G4TsitourasRK45.
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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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G4TsitourasRK45(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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~G4TsitourasRK45() override;
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/**
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* Copy constructor and assignment operator not allowed.
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*/
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G4TsitourasRK45(const G4TsitourasRK45&) = delete;
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G4TsitourasRK45& operator=(const G4TsitourasRK45&) = 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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* Setup all coefficients for interpolation.
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*/
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void SetupInterpolation( /* const G4double yInput[],
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const G4double dydx[],
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const G4double Step */ );
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/**
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* Calculates the output at the tau fraction of step.
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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] Step The given step size.
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* @param[out] yOut Interpolation output.
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* @param[in] tau The tau fraction of the step.
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*/
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void Interpolate( const G4double yInput[],
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const G4double dydx[],
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const G4double Step,
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G4double yOut[],
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G4double tau );
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void interpolate( const G4double yInput[],
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const G4double dydx[],
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G4double yOut[],
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G4double Step,
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G4double tau);
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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, 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, "kTsitourasRK45".
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*/
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inline G4StepperType StepperType() const override { return kTsitourasRK45; }
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private :
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G4double *ak2, *ak3, *ak4, *ak5, *ak6, *ak7, *ak8, *yTemp, *yIn;
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G4double fLastStepLength = 0.0;
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G4double *fLastInitialVector, *fLastFinalVector,
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*fLastDyDx, *fMidVector, *fMidError;
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// For DistChord calculations
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G4TsitourasRK45* fAuxStepper = nullptr;
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};
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#endif
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