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: G4RandomTools.hh,v 1.2 2008/11/07 17:54:21 gum Exp $ |
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28 | // GEANT4 tag $Name: geant4-09-03 $ |
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29 | // |
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30 | // |
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31 | // --------------------------------------------------------------------------- |
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32 | // GEANT 4 class header file |
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33 | // --------------------------------------------------------------------------- |
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34 | // Class description: |
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35 | // |
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36 | // Utility functions |
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37 | |
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38 | // History: |
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39 | // |
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40 | // 07.11.08 - P.Gumplinger, based on implementation in G4OpBoundaryProcess |
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41 | // |
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42 | // --------------------------------------------------------------------------- |
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43 | |
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44 | #ifndef G4RANDOMTOOLS_HH |
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45 | #define G4RANDOMTOOLS_HH |
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46 | |
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47 | #include "globals.hh" |
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48 | #include "Randomize.hh" |
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49 | #include "G4RandomDirection.hh" |
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50 | |
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51 | // --------------------------------------------------------------------------- |
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52 | // Returns a random lambertian unit vector |
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53 | // |
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54 | inline G4ThreeVector G4LambertianRand(const G4ThreeVector& normal) |
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55 | { |
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56 | G4ThreeVector vect; |
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57 | G4double ndotv; |
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58 | |
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59 | do |
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60 | { |
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61 | vect = G4RandomDirection(); |
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62 | ndotv = normal * vect; |
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63 | |
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64 | if (ndotv < 0.0) |
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65 | { |
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66 | vect = -vect; |
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67 | ndotv = -ndotv; |
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68 | } |
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69 | |
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70 | } while (!(G4UniformRand() < ndotv)); |
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71 | |
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72 | return vect; |
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73 | } |
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74 | |
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75 | // --------------------------------------------------------------------------- |
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76 | // Chooses a random vector within a plane given by the unit normal |
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77 | // |
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78 | inline G4ThreeVector G4PlaneVectorRand(const G4ThreeVector& normal) |
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79 | { |
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80 | G4ThreeVector vec1 = normal.orthogonal(); |
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81 | G4ThreeVector vec2 = vec1.cross(normal); |
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82 | |
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83 | G4double phi = twopi*G4UniformRand(); |
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84 | G4double cosphi = std::cos(phi); |
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85 | G4double sinphi = std::sin(phi); |
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86 | |
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87 | return cosphi * vec1 + sinphi * vec2; |
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88 | } |
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89 | |
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90 | #endif /* G4RANDOMTOOLS_HH */ |
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