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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