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00001 // $Id: RandChiSquare.h,v 1.5 2010/06/16 17:24:53 garren Exp $ 00002 // -*- C++ -*- 00003 // 00004 // ----------------------------------------------------------------------- 00005 // HEP Random 00006 // --- RandChiSquare --- 00007 // class header file 00008 // ----------------------------------------------------------------------- 00009 00010 // Class defining methods for shooting Chi^2 distributed random values, 00011 // given a number of degrees of freedom a (default=1.0). 00012 // Default values are used for operator()(). 00013 00014 // Valid values of a satisfy a > 1. When invalid values are presented, 00015 // the code silently returns -1.0. 00016 00017 // ======================================================================= 00018 // John Marraffino - Created: 12th May 1998 Based on the C-Rand package 00019 // by Ernst Stadlober and Franz Niederl of the Technical 00020 // University of Graz, Austria. 00021 // Gabriele Cosmo - Removed useless methods and data: 5th Jan 1999 00022 // M Fischler - put and get to/from streams 12/10/04 00023 // ======================================================================= 00024 00025 #ifndef RandChiSquare_h 00026 #define RandChiSquare_h 1 00027 00028 #include "CLHEP/Random/defs.h" 00029 #include "CLHEP/Random/Random.h" 00030 #include "CLHEP/Utility/memory.h" 00031 00032 namespace CLHEP { 00033 00038 class RandChiSquare : public HepRandom { 00039 00040 public: 00041 00042 inline RandChiSquare ( HepRandomEngine& anEngine, double a=1 ); 00043 inline RandChiSquare ( HepRandomEngine* anEngine, double a=1 ); 00044 // These constructors should be used to instantiate a RandChiSquare 00045 // distribution object defining a local engine for it. 00046 // The static generator will be skipped using the non-static methods 00047 // defined below. 00048 // If the engine is passed by pointer the corresponding engine object 00049 // will be deleted by the RandChiSquare destructor. 00050 // If the engine is passed by reference the corresponding engine object 00051 // will not be deleted by the RandChiSquare destructor. 00052 00053 virtual ~RandChiSquare(); 00054 // Destructor 00055 00056 // Static methods to shoot random values using the static generator 00057 00058 static inline double shoot(); 00059 00060 static double shoot( double a ); 00061 00062 static void shootArray ( const int size, double* vect, 00063 double a=1.0 ); 00064 00065 // Static methods to shoot random values using a given engine 00066 // by-passing the static generator. 00067 00068 static inline double shoot( HepRandomEngine* anEngine ); 00069 00070 static double shoot( HepRandomEngine* anEngine, 00071 double a ); 00072 00073 static void shootArray ( HepRandomEngine* anEngine, const int size, 00074 double* vect, double a=1.0 ); 00075 00076 // Methods using the localEngine to shoot random values, by-passing 00077 // the static generator. 00078 00079 inline double fire(); 00080 00081 double fire( double a ); 00082 00083 void fireArray ( const int size, double* vect); 00084 void fireArray ( const int size, double* vect, 00085 double a ); 00086 inline double operator()(); 00087 inline double operator()( double a ); 00088 00089 // Save and restore to/from streams 00090 00091 std::ostream & put ( std::ostream & os ) const; 00092 std::istream & get ( std::istream & is ); 00093 00094 std::string name() const; 00095 HepRandomEngine & engine(); 00096 00097 static std::string distributionName() {return "RandChiSquare";} 00098 // Provides the name of this distribution class 00099 00100 private: 00101 00102 static double genChiSquare( HepRandomEngine *anEngine, double a ); 00103 00104 shared_ptr<HepRandomEngine> localEngine; 00105 double defaultA; 00106 00107 }; 00108 00109 } // namespace CLHEP 00110 00111 #ifdef ENABLE_BACKWARDS_COMPATIBILITY 00112 // backwards compatibility will be enabled ONLY in CLHEP 1.9 00113 using namespace CLHEP; 00114 #endif 00115 00116 #include "CLHEP/Random/RandChiSquare.icc" 00117 00118 #endif