[1199] | 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: G4RandomDirectionTest.cc,v 1.1 2008/03/19 16:53:55 gcosmo Exp $ |
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| 28 | // GEANT4 tag $Name: geant4-09-02-ref-02 $ |
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| 29 | // |
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| 30 | // |
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| 31 | // Test for random direction unit vector algorithm |
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| 32 | // |
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| 33 | // Author: V. Grichine |
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| 34 | // |
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| 35 | // |
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| 36 | // History: |
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| 37 | // |
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| 38 | // 19.03.08 - First implementation |
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| 39 | // ---------------------------------------------------------------------- |
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| 40 | |
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| 41 | #include "G4ios.hh" |
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| 42 | #include <fstream> |
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| 43 | #include <cmath> |
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| 44 | #include <iomanip> |
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| 45 | |
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| 46 | #include "globals.hh" |
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| 47 | #include "Randomize.hh" |
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| 48 | #include "G4RandomDirection.hh" |
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| 49 | #include "G4UnitsTable.hh" |
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| 50 | #include "G4Timer.hh" |
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| 51 | |
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| 52 | /////////////////////////////////////////////////////////////////////// |
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| 53 | // |
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| 54 | // Random algorithm from Geant3 RAND3 |
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| 55 | |
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| 56 | G4ThreeVector IsotropicCubeRand() |
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| 57 | { |
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| 58 | /* Returns a random isotropic unit vector. */ |
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| 59 | |
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| 60 | G4ThreeVector vect; |
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| 61 | G4double len2; |
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| 62 | |
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| 63 | do { |
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| 64 | |
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| 65 | vect.setX(G4UniformRand() - 0.5); |
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| 66 | vect.setY(G4UniformRand() - 0.5); |
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| 67 | vect.setZ(G4UniformRand() - 0.5); |
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| 68 | |
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| 69 | len2 = vect.mag2(); |
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| 70 | |
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| 71 | } while (len2 < 0.01 || len2 > 0.25); |
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| 72 | |
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| 73 | return vect.unit(); |
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| 74 | } |
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| 75 | |
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| 76 | ///////////////////////////////////////////////////////////////////////////// |
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| 77 | // |
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| 78 | // Random distribution over unit radius sphere |
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| 79 | |
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| 80 | G4ThreeVector IsotropicSphereRand() |
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| 81 | { |
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| 82 | G4double cosTheta = 2*G4UniformRand()-1.; |
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| 83 | G4double sinTheta2 = 1. - cosTheta*cosTheta; |
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| 84 | if( sinTheta2 < 0.) sinTheta2 = 0.; |
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| 85 | G4double sinTheta = std::sqrt(sinTheta2); |
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| 86 | G4double phi = twopi*G4UniformRand(); |
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| 87 | return G4ThreeVector(sinTheta*std::cos(phi), |
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| 88 | sinTheta*std::sin(phi), cosTheta).unit(); |
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| 89 | } |
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| 90 | |
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| 91 | /////////////////////////////////////////////////////////////////////////////// |
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| 92 | // |
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| 93 | // 8 quadrants algorithm |
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| 94 | |
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| 95 | G4ThreeVector MKRandomDirection() |
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| 96 | { |
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| 97 | // Randomization in one of 8 Quadrants (x>0, y>0, z>0) |
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| 98 | // |
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| 99 | G4double x=G4UniformRand(), y=G4UniformRand(), z=G4UniformRand(); |
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| 100 | G4double r2= x*x+y*y+z*z; |
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| 101 | while(r2>1.||r2<.000001) |
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| 102 | { |
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| 103 | x = G4UniformRand(); y = G4UniformRand(); z = G4UniformRand(); |
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| 104 | r2=x*x+y*y+z*z; |
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| 105 | } |
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| 106 | G4double r=std::sqrt(r2), quad=G4UniformRand(); |
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| 107 | |
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| 108 | if(quad>0.5) |
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| 109 | { |
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| 110 | if(quad>0.75) |
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| 111 | { |
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| 112 | if(quad>0.875) return G4ThreeVector(-x/r,-y/r,-z/r); |
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| 113 | else return G4ThreeVector(-x/r,-y/r, z/r); |
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| 114 | } |
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| 115 | else |
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| 116 | { |
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| 117 | if(quad>0.625) return G4ThreeVector(-x/r, y/r,-z/r); |
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| 118 | else return G4ThreeVector(-x/r, y/r, z/r); |
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| 119 | } |
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| 120 | } |
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| 121 | else |
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| 122 | { |
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| 123 | if(quad>0.25) |
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| 124 | { |
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| 125 | if(quad>0.375) return G4ThreeVector( x/r,-y/r,-z/r); |
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| 126 | else return G4ThreeVector( x/r,-y/r, z/r); |
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| 127 | } |
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| 128 | else if(quad>0.125) return G4ThreeVector( x/r, y/r,-z/r); |
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| 129 | } |
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| 130 | return G4ThreeVector( x/r, y/r, z/r); |
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| 131 | } |
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| 132 | |
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| 133 | |
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| 134 | ////////////////////////////////////////////////////////////////////////////// |
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| 135 | // |
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| 136 | // Test main program |
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| 137 | |
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| 138 | int main() |
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| 139 | { |
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| 140 | G4int i, iMax = 20; |
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| 141 | |
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| 142 | G4Timer timer; |
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| 143 | |
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| 144 | iMax = 1000000; |
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| 145 | |
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| 146 | timer.Start(); |
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| 147 | for( i = 0; i < iMax; i++ ) |
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| 148 | { |
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| 149 | G4ThreeVector isoVectr = IsotropicCubeRand(); |
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| 150 | } |
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| 151 | timer.Stop(); |
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| 152 | G4cout<<"Total time of volume "<<iMax<<" calls = " |
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| 153 | <<timer.GetUserElapsed()<<" s"<<G4endl<<G4endl; |
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| 154 | |
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| 155 | timer.Start(); |
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| 156 | for( i = 0; i < iMax; i++ ) |
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| 157 | { |
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| 158 | G4ThreeVector isoVectr = IsotropicSphereRand(); |
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| 159 | } |
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| 160 | timer.Stop(); |
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| 161 | G4cout<<"Total time of surface "<<iMax<<" calls = " |
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| 162 | <<timer.GetUserElapsed()<<" s"<<G4endl<<G4endl; |
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| 163 | |
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| 164 | timer.Start(); |
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| 165 | for( i = 0; i < iMax; i++ ) |
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| 166 | { |
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| 167 | G4ThreeVector isoVectr = G4RandomDirection(); |
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| 168 | } |
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| 169 | timer.Stop(); |
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| 170 | G4cout<<"Total time of G4RandomDirection() "<<iMax |
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| 171 | <<" calls = "<<timer.GetUserElapsed() |
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| 172 | <<" s"<<G4endl<<G4endl; |
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| 173 | |
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| 174 | timer.Start(); |
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| 175 | for( i = 0; i < iMax; i++ ) |
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| 176 | { |
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| 177 | G4ThreeVector isoVectr = MKRandomDirection(); |
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| 178 | } |
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| 179 | timer.Stop(); |
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| 180 | G4cout<<"Total time of MKRandomDirection() "<<iMax |
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| 181 | <<" calls = "<<timer.GetUserElapsed() |
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| 182 | <<" s"<<G4endl<<G4endl; |
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| 183 | |
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| 184 | iMax = 1000000; |
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| 185 | G4int j, jMax = 100; |
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| 186 | G4double cosThetaDistr[100], phi[100]; |
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| 187 | |
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| 188 | for( j = 0; j < jMax; j++ ) |
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| 189 | { |
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| 190 | cosThetaDistr[j] = 0.; |
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| 191 | phi[j] = 0.; |
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| 192 | } |
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| 193 | G4double xyPlane, phiNow, cosThetaNow, cosThetaTmp, phiTmp; |
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| 194 | |
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| 195 | for( i = 0; i < iMax; i++ ) |
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| 196 | { |
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| 197 | // G4ThreeVector isoVectr = IsotropicCubeRand(); |
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| 198 | // G4ThreeVector isoVectr = IsotropicSphereRand(); |
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| 199 | G4ThreeVector isoVectr = G4RandomDirection(); |
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| 200 | |
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| 201 | xyPlane = std::sqrt( isoVectr.x()*isoVectr.x() |
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| 202 | + isoVectr.y()*isoVectr.y() ); |
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| 203 | if ( xyPlane ) |
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| 204 | { |
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| 205 | phiNow = std::atan2(isoVectr.y(),isoVectr.x()); |
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| 206 | phiNow += pi; // 0-twopi range |
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| 207 | |
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| 208 | cosThetaNow = isoVectr.z(); |
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| 209 | } |
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| 210 | else |
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| 211 | { |
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| 212 | if ( isoVectr.z() >= 0. ) cosThetaNow = 1.; |
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| 213 | else cosThetaNow = -1.; |
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| 214 | phiNow = twopi*G4UniformRand(); |
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| 215 | } |
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| 216 | for( j = 0; j < jMax; j++ ) |
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| 217 | { |
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| 218 | cosThetaTmp = -1. + 2.*j/jMax; |
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| 219 | |
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| 220 | if( cosThetaTmp >= cosThetaNow ) |
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| 221 | { |
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| 222 | cosThetaDistr[j] += 1.; |
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| 223 | break; |
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| 224 | } |
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| 225 | } |
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| 226 | for( j = 0; j < jMax; j++ ) |
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| 227 | { |
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| 228 | phiTmp = twopi*j/jMax; |
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| 229 | if( phiTmp >= phiNow ) |
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| 230 | { |
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| 231 | phi[j] += 1.; |
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| 232 | break; |
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| 233 | } |
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| 234 | } |
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| 235 | } |
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| 236 | G4cout << G4endl; |
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| 237 | G4cout <<"cosThetaTmp"<<"\t"<<"cosThetaDistr[j]"<<"\t" |
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| 238 | <<"phi/degree"<<"\t"<<"phi[j]"<<G4endl; |
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| 239 | G4cout << G4endl; |
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| 240 | |
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| 241 | for( j = 0; j < jMax; j++ ) |
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| 242 | { |
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| 243 | cosThetaTmp = -1. + 2.*j/jMax; |
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| 244 | phiTmp = twopi*j/jMax; |
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| 245 | G4cout <<cosThetaTmp<<"\t"<<cosThetaDistr[j]<<"\t" |
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| 246 | <<phiTmp/degree<<"\t"<<phi[j]<<G4endl; |
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| 247 | } |
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| 248 | |
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| 249 | G4double mean=0., rms2=0., rms, relDelta; |
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| 250 | |
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| 251 | for( j = 0; j < jMax; j++ ) |
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| 252 | { |
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| 253 | mean += cosThetaDistr[j]; |
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| 254 | } |
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| 255 | mean /= jMax; |
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| 256 | |
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| 257 | for( j = 0; j < jMax; j++ ) |
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| 258 | { |
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| 259 | rms2 += (mean-cosThetaDistr[j])*(mean-cosThetaDistr[j]); |
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| 260 | } |
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| 261 | rms2 /= jMax-1; |
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| 262 | |
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| 263 | rms = std::sqrt(rms2); |
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| 264 | |
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| 265 | relDelta = rms/mean; |
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| 266 | G4cout << G4endl; |
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| 267 | G4cout << "meanCosThetaDistr = "<<mean<<" +- "<<rms |
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| 268 | <<" with relative error = "<<relDelta <<G4endl; |
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| 269 | |
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| 270 | mean = 0; |
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| 271 | rms2 = 0.; |
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| 272 | |
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| 273 | for( j = 0; j < jMax; j++ ) |
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| 274 | { |
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| 275 | mean += phi[j]; |
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| 276 | } |
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| 277 | mean /= jMax; |
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| 278 | |
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| 279 | for( j = 0; j < jMax; j++ ) |
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| 280 | { |
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| 281 | rms2 += (mean-phi[j])*(mean-phi[j]); |
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| 282 | } |
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| 283 | rms2 /= jMax-1; |
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| 284 | |
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| 285 | rms = std::sqrt(rms2); |
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| 286 | |
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| 287 | relDelta = rms/mean; |
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| 288 | G4cout << G4endl; |
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| 289 | G4cout << "meanPhiDistr = "<<mean<<" +- "<<rms |
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| 290 | <<" with relative error = "<<relDelta <<G4endl; |
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| 291 | |
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| 292 | return 1 ; |
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| 293 | } |
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