Gabriele Cosmo
96 lines
3.6 KiB
C++
96 lines
3.6 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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// G4ImplicitEuler
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//
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// Class description:
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//
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// Implicit Euler stepper for magnetic field:
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// x_1 = x_0 + h/2 * ( dx(t_0,x_0) + dx(t_0+h,x_0+h*dx(t_0,x_0) ) )
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//
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// Second order solver.
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// Takes the current derivative and add it to the current position.
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// Takes the output and its derivative. Adds the mean of both
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// derivatives to form the final output.
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// Author: W.Wander (MIT), 12.09.1997
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// -------------------------------------------------------------------
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#ifndef G4IMPLICITEULER_HH
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#define G4IMPLICITEULER_HH
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#include "G4MagErrorStepper.hh"
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/**
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* @brief G4ImplicitEuler implements a Euler stepper for magnetic field
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* with 2nd order solver.
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*/
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class G4ImplicitEuler : public G4MagErrorStepper
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{
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public:
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/**
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* Constructor for G4HelixSimpleRunge.
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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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*/
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G4ImplicitEuler(G4EquationOfMotion* EqRhs,
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G4int numberOfVariables = 6);
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/**
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* Destructor.
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*/
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~G4ImplicitEuler() override;
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/**
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* The stepper function for the integration.
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* @param[in] y Starting values array of integration variables.
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* @param[in] dydx The derivates 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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*/
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void DumbStepper( const G4double y[] ,
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const G4double dydx[] ,
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G4double h ,
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G4double yout[] ) override;
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/**
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* Returns the order, 2, of integration.
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*/
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inline G4int IntegratorOrder() const override { return 2; }
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/**
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* Returns the stepper type-ID, "kImplicitEuler".
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*/
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inline G4StepperType StepperType() const override { return kImplicitEuler; }
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private:
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/** Temporaries, created to avoid new/delete on every call. */
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G4double* dydxTemp = nullptr;
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G4double* yTemp = nullptr;
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};
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#endif
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