Gabriele Cosmo
129 lines
4.9 KiB
C++
129 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. *
|
|
// ********************************************************************
|
|
//
|
|
// G4ExactHelixStepper
|
|
//
|
|
// Class description:
|
|
//
|
|
// Concrete class for particle motion in constant magnetic field.
|
|
// Helix a-la-Explicity Euler: x_1 = x_0 + helix(h)
|
|
// with helix(h) being a helix piece of length h.
|
|
// simplest approach for solving linear differential equations.
|
|
// Take the current derivative and add it to the current position.
|
|
//
|
|
// As the field is assumed constant, an error is not calculated.
|
|
|
|
// Author: John Apostolakis (CERN), 28.01.2005.
|
|
// Implementation adapted from ExplicitEuler by W.Wander
|
|
// --------------------------------------------------------------------
|
|
#ifndef G4EXACTHELIXSTEPPER_HH
|
|
#define G4EXACTHELIXSTEPPER_HH
|
|
|
|
#include "G4Types.hh"
|
|
#include "G4ThreeVector.hh"
|
|
|
|
#include "G4MagIntegratorStepper.hh"
|
|
#include "G4MagHelicalStepper.hh"
|
|
#include "G4Mag_EqRhs.hh"
|
|
|
|
/**
|
|
* @brief G4ExactHelixStepper is a concrete class for particle motion in
|
|
* constant magnetic field. Helix a-la-Explicity Euler: x_1 = x_0 + helix(h)
|
|
* with helix(h) being a helix piece of length h.
|
|
* As the field is assumed constant, an error is not calculated.
|
|
*/
|
|
|
|
class G4ExactHelixStepper : public G4MagHelicalStepper
|
|
{
|
|
public:
|
|
|
|
/**
|
|
* Constructor for G4ExactHelixStepper.
|
|
* @param[in] EqRhs Pointer to the standard equation of motion.
|
|
*/
|
|
G4ExactHelixStepper(G4Mag_EqRhs* EqRhs);
|
|
|
|
/**
|
|
* Default Destructor.
|
|
*/
|
|
~G4ExactHelixStepper() override = default;
|
|
|
|
/**
|
|
* Copy constructor and assignment operator not allowed.
|
|
*/
|
|
G4ExactHelixStepper(const G4ExactHelixStepper&) = delete;
|
|
G4ExactHelixStepper& operator=(const G4ExactHelixStepper&) = delete;
|
|
|
|
/**
|
|
* The stepper for the Runge Kutta integration.
|
|
* The stepsize is fixed, with the step size given by 'h'.
|
|
* Provides helix starting values y[0 to 6].
|
|
* Outputs yout[] and ZERO estimated error yerr[]=0.
|
|
* @param[in] yInput 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;
|
|
|
|
/**
|
|
* Same as Stepper() function above, but should perform a 'dump' step
|
|
* without error calculation. Assuming a constant field, the solution is
|
|
* a helix. Should NOT be called; issues a fatal exception as the Stepper
|
|
* must do all the work.
|
|
*/
|
|
void DumbStepper( const G4double y[],
|
|
G4ThreeVector Bfld,
|
|
G4double h,
|
|
G4double yout[] ) override;
|
|
|
|
/**
|
|
* Estimates the maximum distance of curved solution and chord.
|
|
*/
|
|
G4double DistChord() const override;
|
|
|
|
/**
|
|
* Returns the order, 1, of integration.
|
|
*/
|
|
inline G4int IntegratorOrder() const override { return 1; }
|
|
|
|
/**
|
|
* Returns the stepper type-ID, "kExactHelixStepper".
|
|
*/
|
|
inline G4StepperType StepperType() const override { return kExactHelixStepper; }
|
|
|
|
private:
|
|
|
|
/** Initial value of field at last step. */
|
|
G4ThreeVector fBfieldValue;
|
|
};
|
|
|
|
#endif
|