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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// G4BogackiShampine45
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//
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// Class description:
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//
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// An implementation of the embedded RK method from the following paper
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// by P. Bogacki and L. F. Shampine:
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// "An efficient Runge-Kutta (4,5) pair"
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// Comput. Math. with Appl., vol. 32, no. 6, pp. 15-28, Sep. 1996.
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//
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// An interpolation method provides the value of an intermediate
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// point in a step -- if a step was sucessful.
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//
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// This version can provide the FSAL property of the method,
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// which allows the reuse of the last derivative in the next step,
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// but only by using the additional method GetLastDyDx() (an alternative
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// interface for simpler use of FSAL is under development).
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// Created: Somnath Banerjee, Google Summer of Code 2015, 25 May 2015
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// Supervision: John Apostolakis, CERN
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// --------------------------------------------------------------------
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#ifndef BOGACKI_SHAMPINE_45_HH
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#define BOGACKI_SHAMPINE_45_HH
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#include "G4MagIntegratorStepper.hh"
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class G4BogackiShampine45 : public G4MagIntegratorStepper
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{
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public:
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G4BogackiShampine45(G4EquationOfMotion* EqRhs,
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G4int numberOfVariables = 6,
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G4bool primary = true);
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~G4BogackiShampine45();
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G4BogackiShampine45(const G4BogackiShampine45&) = delete;
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G4BogackiShampine45& operator=(const G4BogackiShampine45&) = delete;
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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[] ) ;
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// This Stepper provides 'dense output'. After a successful
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// step, it is possible to obtain an estimate of the value
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// of the function at an intermediate point of the interval.
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// This requires only two additional evaluations of the
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// derivative (and thus the field).
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inline void SetupInterpolation()
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{
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SetupInterpolationHigh(); // ( yInput, dydx, Step);
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}
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// For calculating the output at the tau fraction of Step
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//
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inline void Interpolate( G4double tau,
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G4double yOut[] ) // Output value
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{
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InterpolateHigh( tau, yOut);
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// InterpolateHigh( yInput, dydx, Step, yOut, tau);
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}
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void SetupInterpolationHigh();
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// For calculating the output at the tau fraction of Step
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//
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void InterpolateHigh( G4double tau,
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G4double yOut[] ) const;
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G4double DistChord() const;
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G4int IntegratorOrder() const { return 4; }
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void GetLastDydx( G4double dyDxLast[] );
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void PrepareConstants(); // Initialise the values of the bi[][] array
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private:
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G4double *ak2, *ak3, *ak4, *ak5, *ak6, *ak7, *ak8,
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*ak9, *ak10, *ak11, *yTemp, *yIn;
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G4double *p[6];
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G4double fLastStepLength = -1.0;
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G4double *fLastInitialVector, *fLastFinalVector, *fLastDyDx,
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*fMidVector, *fMidError;
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// For DistChord calculations
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G4BogackiShampine45* fAuxStepper = nullptr;
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// For chord - until interpolation is proven
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G4bool fPreparedInterpolation = false;
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// Class constants
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static G4bool fPreparedConstants;
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static G4double bi[12][7];
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};
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#endif
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