Gabriele Cosmo
134 lines
4.9 KiB
C++
134 lines
4.9 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. *
|
|
// ********************************************************************
|
|
//
|
|
// $Id: G4NystromRK4.hh 66356 2012-12-18 09:02:32Z gcosmo $
|
|
//
|
|
// class G4NystromRK4
|
|
//
|
|
// Class description:
|
|
//
|
|
// Integrate the equations of the motion of a particle in a magnetic field
|
|
// using 4th Runge-Kutta-Nystrom method with errors estimation
|
|
// (ATL-SOFT-PUB-2009-01)
|
|
// Current form can be used only for 'pure' magnetic field.
|
|
// Notes: 1) field must be time-independent.
|
|
// 2) time is not integrated
|
|
//
|
|
// History:
|
|
// - Created: I.Gavrilenko 15.05.2009 (as G4AtlasRK4)
|
|
// - Adaptations: J. Apostolakis May-Nov 2009
|
|
// -------------------------------------------------------------------
|
|
|
|
#ifndef G4NYSTROMRK4_HH
|
|
#define G4NYSTROMRK4_HH
|
|
|
|
#include "globals.hh"
|
|
#include "G4MagIntegratorStepper.hh"
|
|
#include "G4Mag_EqRhs.hh"
|
|
|
|
class G4NystromRK4 : public G4MagIntegratorStepper
|
|
{
|
|
public:
|
|
G4NystromRK4(G4Mag_EqRhs *EquationMotion, G4double distanceConstField=0.0);
|
|
// Can be used only for Magnetic Fields - and for 6 variables (x,p)
|
|
|
|
~G4NystromRK4() ;
|
|
|
|
void Stepper(const G4double P [],
|
|
const G4double dPdS[],
|
|
G4double step ,
|
|
G4double Po [],
|
|
G4double Err []);
|
|
// Single call for integration result and error
|
|
// - Provides Error via analytical method
|
|
|
|
virtual void ComputeRightHandSide(const double P[],double dPdS[]);
|
|
// Must compute RHS - and does caches result
|
|
|
|
void SetDistanceForConstantField( G4double length );
|
|
G4double GetDistanceForConstantField() const;
|
|
|
|
G4int IntegratorOrder() const {return 4;}
|
|
G4double DistChord() const;
|
|
|
|
private:
|
|
|
|
inline void getField (const G4double P[4]);
|
|
|
|
////////////////////////////////////////////////////////////////
|
|
// Private data
|
|
////////////////////////////////////////////////////////////////
|
|
|
|
G4Mag_EqRhs* m_fEq;
|
|
G4double m_lastField[3];
|
|
G4double m_fldPosition[4];
|
|
G4double m_magdistance ;
|
|
G4double m_magdistance2;
|
|
G4double m_cof ;
|
|
G4double m_mom ;
|
|
G4double m_imom ;
|
|
G4bool m_cachedMom ;
|
|
G4double m_iPoint [3];
|
|
G4double m_mPoint [3];
|
|
G4double m_fPoint [3];
|
|
|
|
};
|
|
|
|
/////////////////////////////////////////////////////////////////////////////////
|
|
// Inline methods
|
|
/////////////////////////////////////////////////////////////////////////////////
|
|
inline void G4NystromRK4::SetDistanceForConstantField( G4double length )
|
|
{
|
|
m_magdistance= length;
|
|
m_magdistance2 = length*length;
|
|
}
|
|
|
|
inline G4double G4NystromRK4::GetDistanceForConstantField() const
|
|
{
|
|
return m_magdistance;
|
|
}
|
|
|
|
/////////////////////////////////////////////////////////////////////////////////
|
|
// Get value of magnetic field while checking distance from last stored call
|
|
/////////////////////////////////////////////////////////////////////////////////
|
|
|
|
inline void G4NystromRK4::getField (const G4double P[4])
|
|
{
|
|
|
|
G4double dx = P[0]-m_fldPosition[0];
|
|
G4double dy = P[1]-m_fldPosition[1];
|
|
G4double dz = P[2]-m_fldPosition[2];
|
|
|
|
if((dx*dx+dy*dy+dz*dz) > m_magdistance2)
|
|
{
|
|
m_fldPosition[0] = P[0];
|
|
m_fldPosition[1] = P[1];
|
|
m_fldPosition[2] = P[2];
|
|
m_fldPosition[3] = P[3]; // Generally it is P[7] - changed convention !!
|
|
m_fEq->GetFieldValue(m_fldPosition, m_lastField);
|
|
}
|
|
}
|
|
#endif // G4NYSTROMRK4
|