1 | // |
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2 | // ******************************************************************** |
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3 | // * License and Disclaimer * |
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4 | // * * |
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5 | // * The Geant4 software is copyright of the Copyright Holders of * |
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6 | // * the Geant4 Collaboration. It is provided under the terms and * |
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7 | // * conditions of the Geant4 Software License, included in the file * |
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8 | // * LICENSE and available at http://cern.ch/geant4/license . These * |
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9 | // * include a list of copyright holders. * |
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10 | // * * |
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11 | // * Neither the authors of this software system, nor their employing * |
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12 | // * institutes,nor the agencies providing financial support for this * |
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13 | // * work make any representation or warranty, express or implied, * |
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14 | // * regarding this software system or assume any liability for its * |
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15 | // * use. Please see the license in the file LICENSE and URL above * |
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16 | // * for the full disclaimer and the limitation of liability. * |
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17 | // * * |
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18 | // * This code implementation is the result of the scientific and * |
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19 | // * technical work of the GEANT4 collaboration. * |
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20 | // * By using, copying, modifying or distributing the software (or * |
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21 | // * any work based on the software) you agree to acknowledge its * |
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22 | // * use in resulting scientific publications, and indicate your * |
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23 | // * acceptance of all terms of the Geant4 Software license. * |
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24 | // ******************************************************************** |
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25 | // |
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26 | // |
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27 | // $Id: G4Mag_UsualEqRhs.cc,v 1.12 2006/06/29 18:24:42 gunter Exp $ |
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28 | // GEANT4 tag $Name: geant4-09-02-cand-01 $ |
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29 | // |
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30 | // |
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31 | // This is the 'standard' right-hand side for the equation of motion |
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32 | // of a charged particle in a magnetic field. |
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33 | // |
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34 | // Initial version: J. Apostolakis, January 13th, 1997 |
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35 | // |
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36 | // -------------------------------------------------------------------- |
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37 | |
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38 | #include "G4Mag_UsualEqRhs.hh" |
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39 | #include "G4MagneticField.hh" |
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40 | |
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41 | G4Mag_UsualEqRhs::G4Mag_UsualEqRhs( G4MagneticField* MagField ) |
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42 | : G4Mag_EqRhs( MagField ) {} |
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43 | |
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44 | G4Mag_UsualEqRhs::~G4Mag_UsualEqRhs() {} |
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45 | |
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46 | void |
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47 | G4Mag_UsualEqRhs::EvaluateRhsGivenB( const G4double y[], |
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48 | const G4double B[3], |
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49 | G4double dydx[] ) const |
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50 | { |
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51 | G4double momentum_mag_square = y[3]*y[3] + y[4]*y[4] + y[5]*y[5]; |
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52 | G4double inv_momentum_magnitude = 1.0 / std::sqrt( momentum_mag_square ); |
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53 | |
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54 | G4double cof = FCof()*inv_momentum_magnitude; |
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55 | |
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56 | dydx[0] = y[3]*inv_momentum_magnitude; // (d/ds)x = Vx/V |
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57 | dydx[1] = y[4]*inv_momentum_magnitude; // (d/ds)y = Vy/V |
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58 | dydx[2] = y[5]*inv_momentum_magnitude; // (d/ds)z = Vz/V |
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59 | |
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60 | dydx[3] = cof*(y[4]*B[2] - y[5]*B[1]) ; // Ax = a*(Vy*Bz - Vz*By) |
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61 | dydx[4] = cof*(y[5]*B[0] - y[3]*B[2]) ; // Ay = a*(Vz*Bx - Vx*Bz) |
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62 | dydx[5] = cof*(y[3]*B[1] - y[4]*B[0]) ; // Az = a*(Vx*By - Vy*Bx) |
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63 | |
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64 | return ; |
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65 | } |
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66 | |
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67 | void |
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68 | G4Mag_UsualEqRhs:: |
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69 | SetChargeMomentumMass( G4double particleCharge, // in e+ units |
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70 | G4double MomentumXc, |
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71 | G4double mass) |
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72 | |
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73 | { |
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74 | fInvCurrentMomentumXc= 1.0 / MomentumXc; |
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75 | G4Mag_EqRhs::SetChargeMomentumMass( particleCharge, MomentumXc, mass); |
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76 | } |
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