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2 | <!-- Docbook Version: For Toolkit Developers Guide --> |
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3 | <!-- ******************************************************** --> |
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4 | |
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5 | <!-- ******************* Section (Level#1) ****************** --> |
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6 | <sect1 id="sect.DsgnFuncGlobUsg"> |
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7 | <title> |
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8 | Global Usage |
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9 | </title> |
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10 | |
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11 | <!-- ******************* Section (Level#2) ****************** --> |
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12 | <sect2 id="sect.DsgnFuncGlobUsg.DsgPhlsp"> |
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13 | <title> |
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14 | Design Philosophy |
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15 | </title> |
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16 | |
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17 | <para> |
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18 | The global category covers the system of units, constants, numerics and |
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19 | random number handling. It can be considered a place-holder for |
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20 | "general purpose" classes used by all categories defined in Geant4. |
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21 | No back-dependencies to other Geant4 categories affect the "global" |
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22 | domain. There are direct dependencies of the global category on external |
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23 | packages, such as CLHEP, STL, and miscellaneous system utilities. |
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24 | </para> |
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25 | |
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26 | <para> |
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27 | Within the management sub-category are ``utility'' classes generally used |
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28 | within the Geant4 kernel. They are, for the most part, uncorrelated |
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29 | with one another and include: |
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30 | |
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31 | <itemizedlist spacing="compact"> |
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32 | <listitem><para> |
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33 | <emphasis role="italic">G4Allocator</emphasis> |
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34 | </para></listitem> |
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35 | <listitem><para> |
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36 | <emphasis role="italic">G4FastVector</emphasis> |
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37 | </para></listitem> |
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38 | <listitem><para> |
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39 | <emphasis role="italic">G4ReferenceCountedHandle</emphasis> |
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40 | </para></listitem> |
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41 | <listitem><para> |
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42 | <emphasis role="italic">G4PhysicsVector, G4LPhysicsFreeVector, |
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43 | G4PhysicsOrderedFreeVector</emphasis> |
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44 | </para></listitem> |
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45 | <listitem><para> |
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46 | <emphasis role="italic">G4Timer</emphasis> |
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47 | </para></listitem> |
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48 | <listitem><para> |
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49 | <emphasis role="italic">G4UserLimits</emphasis> |
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50 | </para></listitem> |
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51 | <listitem><para> |
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52 | <emphasis role="italic">G4UnitsTable</emphasis> |
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53 | </para></listitem> |
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54 | </itemizedlist> |
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55 | </para> |
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56 | |
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57 | <para> |
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58 | A general description of these classes is given in section 3.2 of the |
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59 | Geant4 User's Guide for Application Developers. |
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60 | </para> |
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61 | |
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62 | <para> |
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63 | In applications where it is necessary to generate random numbers (normally |
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64 | from the same engine) in many different methods and parts of the program, it |
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65 | is highly desirable not to rely on or require knowledge of the global objects |
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66 | instantiated. By using static methods via a unique generator, the randomness |
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67 | of a sequence of numbers is best assured. Hence the use of a static generator |
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68 | has been introduced in the original design of HEPRandom as a project |
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69 | requirement in Geant4. |
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70 | </para> |
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71 | |
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72 | </sect2> |
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73 | |
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74 | <!-- ******************* Section (Level#2) ****************** --> |
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75 | <sect2 id="sect.DsgnFuncGlobUsg.ClassDsg"> |
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76 | <title> |
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77 | Class Design |
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78 | </title> |
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79 | |
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80 | <para> |
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81 | Analysis and design of the HEPRandom module have been achieved following |
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82 | the Booch Object-Oriented methodology. Some of the original design |
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83 | diagrams in Booch notation are reported below. |
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84 | <xref linkend="fig.DsgnFuncGlobUsg_1" /> |
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85 | is a general picture of the static class diagram. |
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86 | |
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87 | <itemizedlist spacing="compact"> |
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88 | <listitem><para> |
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89 | <emphasis role="bold">HepRandomEngine</emphasis> - |
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90 | abstract class defining the interface for each Random engine. Its pure |
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91 | virtual methods must be defined by its subclasses representing the |
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92 | concrete Random engines. |
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93 | </para></listitem> |
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94 | <listitem><para> |
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95 | <emphasis role="bold">HepJamesRandom</emphasis> - |
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96 | class inheriting from HepRandomEngine and defining a flat random number |
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97 | generator according to the algorithm described in |
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98 | "F.James, Comp.Phys.Comm. 60 (1990) 329". This class is instantiated by |
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99 | default as the default random engine. |
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100 | </para></listitem> |
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101 | <listitem><para> |
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102 | <emphasis role="bold">DRand48Engine</emphasis> - |
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103 | class inheriting from HepRandomEngine and defining a flat random number |
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104 | generator according to the drand48() and srand48() system functions from |
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105 | the C standard library. |
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106 | </para></listitem> |
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107 | <listitem><para> |
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108 | <emphasis role="bold">RandEngine</emphasis> - |
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109 | class inheriting from HepRandomEngine and defining a flat random number |
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110 | generator according to the rand() and srand() system functions from the |
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111 | C standard library. |
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112 | </para></listitem> |
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113 | <listitem><para> |
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114 | <emphasis role="bold">RanluxEngine</emphasis> - |
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115 | class inheriting from HepRandomEngine and defining a flat random number |
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116 | generator according to the algorithm described in |
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117 | "F.James, Comp.Phys.Comm. 60 (1990) 329-344" and originally implemented |
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118 | in FORTRAN 77 as part of the MATHLIB HEP library. It provides 5 different |
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119 | "luxury" levels [0..4]. |
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120 | </para></listitem> |
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121 | <listitem><para> |
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122 | <emphasis role="bold">RanecuEngine</emphasis> - |
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123 | class inheriting from HepRandomEngine and defining a flat random number |
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124 | generator according to the algorithm RANECU originally written in |
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125 | FORTRAN 77 as part of the MATHLIB HEP library. It uses a table of seeds |
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126 | which provides uncorrelated couples of seed values. |
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127 | </para></listitem> |
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128 | <listitem><para> |
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129 | <emphasis role="bold">HepRandom</emphasis> - |
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130 | the main class collecting all the methods defining the different random |
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131 | generators applied to HepRandomEngine. It is a singleton class which all |
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132 | the distribution classes derive from. This singleton is instantiated by |
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133 | default. |
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134 | </para></listitem> |
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135 | <listitem><para> |
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136 | <emphasis role="bold">RandFlat</emphasis> - |
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137 | distribution class for flat random number generation. It also provides |
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138 | methods to fill an array of flat random values, given its size or shoot |
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139 | bits. |
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140 | </para></listitem> |
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141 | <listitem><para> |
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142 | <emphasis role="bold">RandExponential</emphasis> - |
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143 | distribution class defining exponential random number distribution, given |
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144 | a mean. It also provides a method to fill an array of flat random values, |
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145 | given its size. |
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146 | </para></listitem> |
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147 | <listitem><para> |
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148 | <emphasis role="bold">RandGauss</emphasis> - |
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149 | distribution class defining Gauss random number distribution, given a |
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150 | mean or specifying also a deviation. It also provides a method to fill |
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151 | an array of flat random values, given its size. |
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152 | </para></listitem> |
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153 | <listitem><para> |
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154 | <emphasis role="bold">RandBreitWigner</emphasis> - |
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155 | distribution class defining the Breit-Wigner random number distribution. |
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156 | It also provides a method to fill an array of flat random values, given |
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157 | its size. |
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158 | </para></listitem> |
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159 | <listitem><para> |
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160 | <emphasis role="bold">RandPoisson</emphasis> - |
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161 | distribution class defining Poisson random number distribution, given a |
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162 | mean. It also provides a method to fill an array of flat random values, |
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163 | given its size. |
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164 | </para></listitem> |
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165 | </itemizedlist> |
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166 | |
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167 | <figure id="fig.DsgnFuncGlobUsg_1"> |
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168 | <title> |
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169 | HEPRandom module |
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170 | </title> |
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171 | <mediaobject> |
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172 | <imageobject role="fo"> |
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173 | <imagedata fileref="./AllResources/OOAnalysisDesign/GlobalUsage/classDgmRandom.jpg" |
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174 | format="JPG" contentwidth="10.0cm" align="center" /> |
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175 | </imageobject> |
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176 | <imageobject role="html"> |
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177 | <imagedata fileref="./AllResources/OOAnalysisDesign/GlobalUsage/classDgmRandom.jpg" |
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178 | format="JPG" contentwidth="120%" align="center" /> |
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179 | </imageobject> |
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180 | </mediaobject> |
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181 | </figure> |
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182 | </para> |
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183 | |
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184 | <para> |
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185 | <xref linkend="fig.DsgnFuncGlobUsg_2" /> is a dynamic object diagram illustrating the |
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186 | situation when a single random number is thrown by the static generator |
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187 | according to one of the available distributions. Only one engine is |
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188 | assumed to active at a time. |
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189 | |
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190 | <figure id="fig.DsgnFuncGlobUsg_2"> |
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191 | <title> |
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192 | Shooting via the generator |
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193 | </title> |
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194 | <mediaobject> |
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195 | <imageobject role="fo"> |
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196 | <imagedata fileref="./AllResources/OOAnalysisDesign/GlobalUsage/ObjDiagStat.jpg" |
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197 | format="JPG" contentwidth="10.0cm" align="center" /> |
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198 | </imageobject> |
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199 | <imageobject role="html"> |
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200 | <imagedata fileref="./AllResources/OOAnalysisDesign/GlobalUsage/ObjDiagStat.jpg" |
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201 | format="JPG" contentwidth="120%" align="center" /> |
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202 | </imageobject> |
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203 | </mediaobject> |
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204 | </figure> |
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205 | </para> |
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206 | |
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207 | <para> |
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208 | <xref linkend="fig.DsgnFuncGlobUsg_3" /> illustrates a random number being thrown by |
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209 | explicitly specifying an engine which can be shared by many distribution |
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210 | objects. The static interface is skipped here. |
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211 | |
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212 | <figure id="fig.DsgnFuncGlobUsg_3"> |
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213 | <title> |
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214 | Shooting via distribution objects |
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215 | </title> |
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216 | <mediaobject> |
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217 | <imageobject role="fo"> |
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218 | <imagedata fileref="./AllResources/OOAnalysisDesign/GlobalUsage/ObjDiagDist.jpg" |
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219 | format="JPG" contentwidth="10.0cm" align="center" /> |
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220 | </imageobject> |
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221 | <imageobject role="html"> |
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222 | <imagedata fileref="./AllResources/OOAnalysisDesign/GlobalUsage/ObjDiagDist.jpg" |
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223 | format="JPG" contentwidth="120%" align="center" /> |
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224 | </imageobject> |
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225 | </mediaobject> |
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226 | </figure> |
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227 | </para> |
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228 | |
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229 | <para> |
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230 | <xref linkend="fig.DsgnFuncGlobUsg_4" /> illustrates the situation when many |
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231 | generators are defined, each by a distribution and an engine. The static |
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232 | interface is skipped here. |
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233 | |
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234 | <figure id="fig.DsgnFuncGlobUsg_4"> |
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235 | <title> |
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236 | Shooting with arbitrary engines |
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237 | </title> |
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238 | <mediaobject> |
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239 | <imageobject role="fo"> |
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240 | <imagedata fileref="./AllResources/OOAnalysisDesign/GlobalUsage/ObjDiagEng.jpg" |
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241 | format="JPG" contentwidth="10.0cm" align="center" /> |
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242 | </imageobject> |
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243 | <imageobject role="html"> |
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244 | <imagedata fileref="./AllResources/OOAnalysisDesign/GlobalUsage/ObjDiagEng.jpg" |
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245 | format="JPG" contentwidth="120%" align="center" /> |
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246 | </imageobject> |
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247 | </mediaobject> |
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248 | </figure> |
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249 | </para> |
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250 | |
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251 | <para> |
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252 | For detailed documentation about the HEPRandom classes see the |
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253 | CLHEP Reference Guide(http://cern.ch/clhep/manual/RefGuide) |
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254 | or the CLHEP User Manua(http://cern.ch/clhep/manual/UserGuide). |
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255 | </para> |
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256 | |
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257 | <para> |
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258 | Informations written in this manual are extracted |
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259 | from the original manifesto distributed with the HEPRandom package |
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260 | (http://cern.ch/clhep/manual/UserGuide/Random/Random.html). |
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261 | </para> |
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262 | |
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263 | <!-- ******* Bridgehead ******* --> |
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264 | <bridgehead renderas='sect4'> |
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265 | HEPNumerics |
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266 | </bridgehead> |
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267 | |
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268 | <para> |
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269 | The HEPNumerics module includes a set of classes which implement numerical |
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270 | algorithms for general use in Geant4. The User's Guide |
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271 | for Application Developers contains a description of each class. Most of |
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272 | the algorithms were implemented using methods from the following books: |
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273 | |
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274 | <itemizedlist spacing="compact"> |
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275 | <listitem><para> |
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276 | B.H. Flowers, "An introduction to Numerical Methods In C++", |
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277 | Claredon Press, Oxford 1995. |
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278 | </para></listitem> |
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279 | <listitem><para> |
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280 | M. Abramowitz, I. Stegun, "Handbook of mathematical functions", |
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281 | DOVER Publications INC, New York 1965 ; chapters 9, 10, and 22. |
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282 | </para></listitem> |
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283 | </itemizedlist> |
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284 | </para> |
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285 | |
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286 | |
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287 | <!-- ******* Bridgehead ******* --> |
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288 | <bridgehead renderas='sect4'> |
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289 | HEPGeometry |
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290 | </bridgehead> |
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291 | |
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292 | <para> |
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293 | Documentation for the HEPGeometry module is provided in the CLHEP |
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294 | Reference Guide(http://cern.ch/clhep/manual/RefGuide) |
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295 | or the CLHEP User Manual(http://cern.ch/clhep/manual/UserGuide). |
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296 | </para> |
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297 | |
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298 | <!-- ******* Bridgehead ******* --> |
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299 | <bridgehead role="revisionHistory" renderas="sect4"> |
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300 | [Status of this chapter] |
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301 | </bridgehead> |
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302 | <para> |
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303 | <simplelist type="var"> |
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304 | <member> |
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305 | 01.12.02 minor update by G. Cosmo |
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306 | </member> |
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307 | <member> |
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308 | 18.06.05 introductory paragraphs added and minor grammar changes by D.H. Wright |
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309 | </member> |
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310 | <member> |
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311 | Dec. 2006 Conversion from latex to Docbook verson by K. Amako |
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312 | </member> |
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313 | </simplelist> |
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314 | </para> |
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315 | |
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316 | |
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317 | </sect2> |
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318 | </sect1> |
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