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: G4ErrorMag_UsualEqRhs.cc,v 1.1 2007/05/16 12:54:02 gcosmo Exp $ |
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28 | // GEANT4 tag $Name: $ |
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29 | // |
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30 | // |
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31 | // -------------------------------------------------------------------- |
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32 | // GEANT 4 class implementation file |
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33 | // -------------------------------------------------------------------- |
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34 | |
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35 | #include "G4ErrorMag_UsualEqRhs.hh" |
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36 | #include "G4ErrorPropagatorData.hh" |
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37 | |
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38 | //--------------------------------------------------------------------- |
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39 | |
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40 | G4ErrorMag_UsualEqRhs::G4ErrorMag_UsualEqRhs( G4MagneticField* MagField ) |
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41 | : G4Mag_UsualEqRhs( MagField ) |
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42 | { |
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43 | } |
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44 | |
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45 | G4ErrorMag_UsualEqRhs::~G4ErrorMag_UsualEqRhs() |
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46 | { |
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47 | } |
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48 | |
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49 | //--------------------------------------------------------------------- |
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50 | void |
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51 | G4ErrorMag_UsualEqRhs::EvaluateRhsGivenB( const G4double y[], |
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52 | const G4double B[3], |
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53 | G4double dydx[] ) const |
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54 | { |
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55 | |
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56 | G4Mag_UsualEqRhs::EvaluateRhsGivenB(y, B, dydx ); |
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57 | |
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58 | if(G4ErrorPropagatorData::GetErrorPropagatorData()->GetMode() |
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59 | == G4ErrorMode_PropBackwards) |
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60 | { |
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61 | G4double momentum_mag_square = sqr(y[3]) + sqr(y[4]) + sqr(y[5]); |
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62 | G4double inv_momentum_magnitude = 1.0 / std::sqrt( momentum_mag_square ); |
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63 | |
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64 | G4double cof = FCof()*inv_momentum_magnitude; |
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65 | |
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66 | dydx[3] = cof*(y[4]*(-B[2]) - y[5]*(-B[1])) ; |
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67 | dydx[4] = cof*(y[5]*(-B[0]) - y[3]*(-B[2])) ; |
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68 | dydx[5] = cof*(y[3]*(-B[1]) - y[4]*(-B[0])) ; |
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69 | } |
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70 | return; |
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71 | } |
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