00001 // 00002 // ******************************************************************** 00003 // * License and Disclaimer * 00004 // * * 00005 // * The Geant4 software is copyright of the Copyright Holders of * 00006 // * the Geant4 Collaboration. It is provided under the terms and * 00007 // * conditions of the Geant4 Software License, included in the file * 00008 // * LICENSE and available at http://cern.ch/geant4/license . These * 00009 // * include a list of copyright holders. * 00010 // * * 00011 // * Neither the authors of this software system, nor their employing * 00012 // * institutes,nor the agencies providing financial support for this * 00013 // * work make any representation or warranty, express or implied, * 00014 // * regarding this software system or assume any liability for its * 00015 // * use. Please see the license in the file LICENSE and URL above * 00016 // * for the full disclaimer and the limitation of liability. * 00017 // * * 00018 // * This code implementation is the result of the scientific and * 00019 // * technical work of the GEANT4 collaboration. * 00020 // * By using, copying, modifying or distributing the software (or * 00021 // * any work based on the software) you agree to acknowledge its * 00022 // * use in resulting scientific publications, and indicate your * 00023 // * acceptance of all terms of the Geant4 Software license. * 00024 // ******************************************************************** 00025 // 00026 // 00027 // $Id: G4Mag_UsualEqRhs.cc 69786 2013-05-15 09:38:51Z gcosmo $ 00028 // 00029 // 00030 // This is the 'standard' right-hand side for the equation of motion 00031 // of a charged particle in a magnetic field. 00032 // 00033 // Initial version: J. Apostolakis, January 13th, 1997 00034 // 00035 // -------------------------------------------------------------------- 00036 00037 #include "G4Mag_UsualEqRhs.hh" 00038 #include "G4MagneticField.hh" 00039 00040 #include "globals.hh" // For DBL_MAX 00041 00042 G4Mag_UsualEqRhs::G4Mag_UsualEqRhs( G4MagneticField* MagField ) 00043 : G4Mag_EqRhs( MagField ) {} 00044 00045 G4Mag_UsualEqRhs::~G4Mag_UsualEqRhs() {} 00046 00047 void 00048 G4Mag_UsualEqRhs::EvaluateRhsGivenB( const G4double y[], 00049 const G4double B[3], 00050 G4double dydx[] ) const 00051 { 00052 G4double momentum_mag_square = y[3]*y[3] + y[4]*y[4] + y[5]*y[5]; 00053 G4double inv_momentum_magnitude = 1.0 / std::sqrt( momentum_mag_square ); 00054 00055 G4double cof = FCof()*inv_momentum_magnitude; 00056 00057 dydx[0] = y[3]*inv_momentum_magnitude; // (d/ds)x = Vx/V 00058 dydx[1] = y[4]*inv_momentum_magnitude; // (d/ds)y = Vy/V 00059 dydx[2] = y[5]*inv_momentum_magnitude; // (d/ds)z = Vz/V 00060 00061 dydx[3] = cof*(y[4]*B[2] - y[5]*B[1]) ; // Ax = a*(Vy*Bz - Vz*By) 00062 dydx[4] = cof*(y[5]*B[0] - y[3]*B[2]) ; // Ay = a*(Vz*Bx - Vx*Bz) 00063 dydx[5] = cof*(y[3]*B[1] - y[4]*B[0]) ; // Az = a*(Vx*By - Vy*Bx) 00064 00065 return ; 00066 } 00067 00068 void 00069 G4Mag_UsualEqRhs:: 00070 SetChargeMomentumMass( G4double particleCharge, // in e+ units 00071 G4double MomentumXc, 00072 G4double mass) 00073 00074 { 00075 G4Mag_EqRhs::SetChargeMomentumMass( particleCharge, MomentumXc, mass); 00076 }