Gabriele Cosmo
167 lines
6.2 KiB
C++
167 lines
6.2 KiB
C++
//
|
|
// ********************************************************************
|
|
// * License and Disclaimer *
|
|
// * *
|
|
// * The Geant4 software is copyright of the Copyright Holders of *
|
|
// * the Geant4 Collaboration. It is provided under the terms and *
|
|
// * conditions of the Geant4 Software License, included in the file *
|
|
// * LICENSE and available at http://cern.ch/geant4/license . These *
|
|
// * include a list of copyright holders. *
|
|
// * *
|
|
// * Neither the authors of this software system, nor their employing *
|
|
// * institutes,nor the agencies providing financial support for this *
|
|
// * work make any representation or warranty, express or implied, *
|
|
// * regarding this software system or assume any liability for its *
|
|
// * use. Please see the license in the file LICENSE and URL above *
|
|
// * for the full disclaimer and the limitation of liability. *
|
|
// * *
|
|
// * This code implementation is the result of the scientific and *
|
|
// * technical work of the GEANT4 collaboration. *
|
|
// * By using, copying, modifying or distributing the software (or *
|
|
// * any work based on the software) you agree to acknowledge its *
|
|
// * use in resulting scientific publications, and indicate your *
|
|
// * acceptance of all terms of the Geant4 Software license. *
|
|
// ********************************************************************
|
|
//
|
|
// G4BogackiShampine45
|
|
//
|
|
// Class description:
|
|
//
|
|
// An implementation of the embedded RK method from the following paper
|
|
// by P. Bogacki and L. F. Shampine:
|
|
// "An efficient Runge-Kutta (4,5) pair"
|
|
// Comput. Math. with Appl., vol. 32, no. 6, pp. 15-28, Sep. 1996.
|
|
//
|
|
// An interpolation method provides the value of an intermediate
|
|
// point in a step -- if a step was sucessful.
|
|
//
|
|
// This version can provide the FSAL property of the method,
|
|
// which allows the reuse of the last derivative in the next step,
|
|
// but only by using the additional method GetLastDyDx() (an alternative
|
|
// interface for simpler use of FSAL is under development).
|
|
|
|
// Author: Somnath Banerjee (CERN, Google Summer of Code 2015), 25.05.2015
|
|
// Supervision: John Apostolakis (CERN)
|
|
// --------------------------------------------------------------------
|
|
#ifndef BOGACKI_SHAMPINE_45_HH
|
|
#define BOGACKI_SHAMPINE_45_HH
|
|
|
|
#include "G4MagIntegratorStepper.hh"
|
|
|
|
/**
|
|
* @brief G4BogackiShampine45 is an integrator of particle's equation of
|
|
* motion based on the Bogacki-Shampine method with FSAL property, allowing
|
|
* the reuse of the last derivative in the next step.
|
|
* This Stepper provides 'dense output'. After a successful step, it is
|
|
* possible to obtain an estimate of the value of the function at an
|
|
* intermediate point of the interval. This requires only two additional
|
|
* evaluations of the derivative (and thus the field).
|
|
*/
|
|
|
|
class G4BogackiShampine45 : public G4MagIntegratorStepper
|
|
{
|
|
public:
|
|
|
|
/**
|
|
* Constructor for G4BogackiShampine45.
|
|
* @param[in] EqRhs Pointer to the provided equation of motion.
|
|
* @param[in] numberOfVariables The number of integration variables.
|
|
* @param[in] primary Flag for initialisation of the auxiliary stepper.
|
|
*/
|
|
G4BogackiShampine45(G4EquationOfMotion* EqRhs,
|
|
G4int numberOfVariables = 6,
|
|
G4bool primary = true);
|
|
|
|
/**
|
|
* Destructor.
|
|
*/
|
|
~G4BogackiShampine45() override;
|
|
|
|
/**
|
|
* Copy constructor and assignment operator not allowed.
|
|
*/
|
|
G4BogackiShampine45(const G4BogackiShampine45&) = delete;
|
|
G4BogackiShampine45& operator=(const G4BogackiShampine45&) = delete;
|
|
|
|
/**
|
|
* The stepper for the Runge Kutta integration.
|
|
* The stepsize is fixed, with the step size given by 'h'.
|
|
* Integrates ODE starting values y[0 to 6].
|
|
* Outputs yout[] and its estimated error yerr[].
|
|
* @param[in] y Starting values array of integration variables.
|
|
* @param[in] dydx Derivatives array.
|
|
* @param[in] h The given step size.
|
|
* @param[out] yout Integration output.
|
|
* @param[out] yerr The estimated error.
|
|
*/
|
|
void Stepper( const G4double y[],
|
|
const G4double dydx[],
|
|
G4double h,
|
|
G4double yout[],
|
|
G4double yerr[] ) override;
|
|
|
|
/**
|
|
* Setup all coefficients for interpolation.
|
|
*/
|
|
void SetupInterpolationHigh(); // ( yInput, dydx, Step);
|
|
inline void SetupInterpolation() { SetupInterpolationHigh(); }
|
|
|
|
/**
|
|
* Calculates the output at the tau fraction of step.
|
|
* @param[in] tau The tau fraction of the step.
|
|
* @param[out] yOut Interpolation output.
|
|
*/
|
|
void InterpolateHigh( G4double tau, G4double yOut[] ) const;
|
|
inline void Interpolate( G4double tau,
|
|
G4double yOut[] ) { InterpolateHigh( tau, yOut); }
|
|
|
|
/**
|
|
* Returns the distance from chord line.
|
|
*/
|
|
G4double DistChord() const override;
|
|
|
|
/**
|
|
* Returns the order, 4, of integration.
|
|
*/
|
|
inline G4int IntegratorOrder() const override { return 4; }
|
|
|
|
/**
|
|
* Returns the stepper type-ID, "kBogackiShampine45".
|
|
*/
|
|
inline G4StepperType StepperType() const override { return kBogackiShampine45; }
|
|
|
|
/**
|
|
* Acccessor for dydx array.
|
|
*/
|
|
void GetLastDydx( G4double dyDxLast[] );
|
|
|
|
/**
|
|
* Initialises the values of the bi[][] array.
|
|
*/
|
|
void PrepareConstants();
|
|
|
|
private:
|
|
|
|
G4double *ak2, *ak3, *ak4, *ak5, *ak6, *ak7, *ak8,
|
|
*ak9, *ak10, *ak11, *yTemp, *yIn;
|
|
|
|
G4double *p[6];
|
|
|
|
G4double fLastStepLength = -1.0;
|
|
|
|
/** For DistChord() calculations. */
|
|
G4double *fLastInitialVector, *fLastFinalVector, *fLastDyDx,
|
|
*fMidVector, *fMidError;
|
|
|
|
G4BogackiShampine45* fAuxStepper = nullptr;
|
|
|
|
/** For chord - until interpolation is proven. */
|
|
G4bool fPreparedInterpolation = false;
|
|
|
|
/** Class constants. */
|
|
static G4bool fPreparedConstants;
|
|
static G4double bi[12][7];
|
|
};
|
|
|
|
#endif
|