Gabriele Cosmo
109 lines
4.1 KiB
C++
109 lines
4.1 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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// G4TMagFieldEquation
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//
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// Class description:
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//
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// Templated version of equation of motion of a particle in a pure
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// magnetic field.
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// Enables use of inlined code for field, equation, stepper, driver,
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// avoiding all virtual calls.
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//
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// Adapted from G4Mag_UsualEqRhs.
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//
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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 G4TMAGFIELD_EQUATION_HH
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#define G4TMAGFIELD_EQUATION_HH
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#include "G4Mag_UsualEqRhs.hh"
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/**
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* @brief G4TMagFieldEquation is a templated version of G4MagFieldEquation.
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*/
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template <class T_Field>
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class G4TMagFieldEquation : public G4Mag_UsualEqRhs
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{
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public:
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G4TMagFieldEquation(T_Field* f) : G4Mag_UsualEqRhs(f)
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{
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itsField = f;
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}
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virtual ~G4TMagFieldEquation() = default;
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inline void GetFieldValue(const G4double Point[4],
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G4double Field[]) const
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{
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itsField->T_Field::GetFieldValue(Point, Field);
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}
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inline void TEvaluateRhsGivenB( const G4double y[],
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const G4double B[3],
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G4double dydx[] ) const
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{
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G4double momentum_mag_square = y[3]*y[3] + y[4]*y[4] + y[5]*y[5];
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G4double inv_momentum_magnitude = 1.0 / std::sqrt( momentum_mag_square );
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G4double cof = FCof()*inv_momentum_magnitude;
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dydx[0] = y[3]*inv_momentum_magnitude; // (d/ds)x = Vx/V
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dydx[1] = y[4]*inv_momentum_magnitude; // (d/ds)y = Vy/V
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dydx[2] = y[5]*inv_momentum_magnitude; // (d/ds)z = Vz/V
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dydx[3] = cof*(y[4]*B[2] - y[5]*B[1]) ; // Ax = a*(Vy*Bz - Vz*By)
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dydx[4] = cof*(y[5]*B[0] - y[3]*B[2]) ; // Ay = a*(Vz*Bx - Vx*Bz)
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dydx[5] = cof*(y[3]*B[1] - y[4]*B[0]) ; // Az = a*(Vx*By - Vy*Bx)
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return ;
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}
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__attribute__((always_inline))
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void RightHandSide( const G4double y[], G4double dydx[] )
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// const
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{
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G4double Field[G4maximum_number_of_field_components];
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G4double PositionAndTime[4];
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PositionAndTime[0] = y[0];
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PositionAndTime[1] = y[1];
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PositionAndTime[2] = y[2];
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PositionAndTime[3] = y[7];
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GetFieldValue(PositionAndTime, Field) ;
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TEvaluateRhsGivenB(y, Field, dydx);
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}
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private:
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enum { G4maximum_number_of_field_components = 24 };
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// Dependent objects
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T_Field* itsField;
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};
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#endif
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