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00001 // $Id: RandPoisson.h,v 1.3.4.1 2005/03/18 22:26:48 garren Exp $ 00002 // -*- C++ -*- 00003 // 00004 // ----------------------------------------------------------------------- 00005 // HEP Random 00006 // --- RandPoisson --- 00007 // class header file 00008 // ----------------------------------------------------------------------- 00009 // This file is part of Geant4 (simulation toolkit for HEP). 00010 00011 // Class defining methods for shooting numbers according to the Poisson 00012 // distribution, given a mean (Algorithm taken from "W.H.Press et al., 00013 // Numerical Recipes in C, Second Edition". 00014 // Default mean value is set to 1, value used for operator()(). 00015 00016 // ======================================================================= 00017 // Gabriele Cosmo - Created: 5th September 1995 00018 // - Added not static Shoot() method: 17th May 1996 00019 // - Algorithm now operates on doubles : 31st Oct 1996 00020 // - Added methods to shoot arrays: 28th July 1997 00021 // J.Marraffino - Added default mean as attribute and 00022 // operator() with mean: 16th Feb 1998 00023 // Gabriele Cosmo - Relocated static data from HepRandom: 5th Jan 1999 00024 // M. Fischler - Moved meanMax and defaultMean from private to protected 00025 // to accomodate derived classes RandPoissonQ & RandPoissonT 00026 // M Fischler - put and get to/from streams 12/10/04 00027 // ======================================================================= 00028 00029 #ifndef RandPoisson_h 00030 #define RandPoisson_h 1 00031 00032 #include "CLHEP/Random/defs.h" 00033 #include "CLHEP/Random/Random.h" 00034 00035 namespace CLHEP { 00036 00041 class RandPoisson : public HepRandom { 00042 00043 public: 00044 00045 inline RandPoisson ( HepRandomEngine& anEngine, double m=1.0 ); 00046 inline RandPoisson ( HepRandomEngine* anEngine, double m=1.0 ); 00047 // These constructors should be used to instantiate a RandPoisson 00048 // distribution object defining a local engine for it. 00049 // The static generator will be skipped using the non-static methods 00050 // defined below. 00051 // If the engine is passed by pointer the corresponding engine object 00052 // will be deleted by the RandPoisson destructor. 00053 // If the engine is passed by reference the corresponding engine object 00054 // will not be deleted by the RandPoisson destructor. 00055 00056 virtual ~RandPoisson(); 00057 // Destructor 00058 00059 // Save and restore to/from streams 00060 00061 std::ostream & put ( std::ostream & os ) const; 00062 std::istream & get ( std::istream & is ); 00063 00064 // Static methods to shoot random values using the static generator 00065 00066 static long shoot( double m=1.0 ); 00067 00068 static void shootArray ( const int size, long* vect, double m=1.0 ); 00069 00070 // Static methods to shoot random values using a given engine 00071 // by-passing the static generator. 00072 00073 static long shoot( HepRandomEngine* anEngine, double m=1.0 ); 00074 00075 static void shootArray ( HepRandomEngine* anEngine, 00076 const int size, long* vect, double m=1.0 ); 00077 00078 // Methods using the localEngine to shoot random values, by-passing 00079 // the static generator. 00080 00081 long fire(); 00082 long fire( double m ); 00083 00084 void fireArray ( const int size, long* vect ); 00085 void fireArray ( const int size, long* vect, double m); 00086 00087 double operator()(); 00088 double operator()( double m ); 00089 00090 std::string name() const; 00091 HepRandomEngine & engine(); 00092 00093 static std::string distributionName() {return "RandPoisson";} 00094 // Provides the name of this distribution class 00095 00096 protected: 00097 00098 // Protected copy constructor. Defining it here disallows user use. 00099 RandPoisson(const RandPoisson& d); 00100 00101 double meanMax; 00102 double defaultMean; 00103 00104 static double getOldMean() {return oldm_st;} 00105 00106 static double getMaxMean() {return meanMax_st;} 00107 00108 static void setOldMean( double val ){oldm_st = val;} 00109 00110 static double* getPStatus() {return status_st;} 00111 00112 static void setPStatus(double sq, double alxm, double g) { 00113 status_st[0] = sq; status_st[1] = alxm; status_st[2] = g; 00114 } 00115 00116 inline HepRandomEngine* getLocalEngine(); 00117 00118 private: 00119 00120 HepRandomEngine* localEngine; 00121 bool deleteEngine; 00122 double status[3], oldm; 00123 00124 // static data 00125 static double status_st[3]; 00126 static double oldm_st; 00127 static const double meanMax_st; 00128 00129 }; 00130 00131 } // namespace CLHEP 00132 00133 #ifdef ENABLE_BACKWARDS_COMPATIBILITY 00134 // backwards compatibility will be enabled ONLY in CLHEP 1.9 00135 using namespace CLHEP; 00136 #endif 00137 00138 #include "CLHEP/Random/RandPoisson.icc" 00139 00140 #endif