Gabriele Cosmo
100 lines
3.8 KiB
C++
100 lines
3.8 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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// G4TExplicitEuler
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//
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// Class description:
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//
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// Templated version of G4ExplicitEuler.
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// Adapted from G4G4TExplicitEuler class.
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//
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// Information from G4Explicit Euler:
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// ----------------------------------
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// Explicit Euler stepper for magnetic field: x_1 = x_0 + h * dx_0.
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// The simplistic approach to solving linear differential equations.
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// Take the current derivative and add it to the current position.
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// Author: Josh Xie (CERN, Google Summer of Code 2014), June 2014
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// Supervisors: Sandro Wenzel, John Apostolakis (CERN)
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// --------------------------------------------------------------------
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#ifndef G4TExplicitEuler_HH
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#define G4TExplicitEuler_HH
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#include "G4TMagErrorStepper.hh"
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#include "G4ThreeVector.hh"
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/**
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* @brief G4TExplicitEuler is a templated version of G4ExplicitEuler stepper.
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*/
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template <class T_Equation, int N>
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class G4TExplicitEuler
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: public G4TMagErrorStepper<G4TExplicitEuler<T_Equation, N>, T_Equation, N>
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{
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public:
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static constexpr double IntegratorCorrection = 1.;
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G4TExplicitEuler(T_Equation* EqRhs, G4int numberOfVariables = N)
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: G4TMagErrorStepper<G4TExplicitEuler<T_Equation, N>, T_Equation, N>
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(EqRhs, numberOfVariables), fEquation_Rhs(EqRhs)
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{
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if( numberOfVariables != N )
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{
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G4ExceptionDescription msg;
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msg << "Equation has an incompatible number of variables." ;
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msg << " template N = " << N << " equation-Nvar= "
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<< numberOfVariables;
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G4Exception("G4TExplicitEuler: constructor", "GeomField0003",
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FatalErrorInArgument, msg );
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}
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}
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~G4TExplicitEuler() = default;
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inline void DumbStepper(const G4double yIn[],
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const G4double dydx[],
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G4double h, G4double yOut[]) // override final
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{
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// Initialise time to t0, needed when it is not updated by the integration.
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// yOut[7] = yIn[7]; // Better to set it to NaN; // TODO
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for(G4int i = 0; i < N; ++i)
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{
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yOut[i] = yIn[i] + h * dydx[i]; // 1st and only Step
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}
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return;
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}
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G4int IntegratorOrder() const { return 1; }
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private:
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T_Equation* fEquation_Rhs;
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};
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#endif
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