| Geant4 Cross Reference |
1 /* 1
2 Code adapted from:
3 http://www.jstatsoft.org/v05/i08/
4
5
6 Original disclaimer:
7
8 The ziggurat method for RNOR and REXP
9 Combine the code below with the main program i
10 normal or exponential variates. Then use of
11 will provide a standard normal variate with me
12 while use of REXP in any expression will provi
13 with density exp(-x),x>0.
14 Before using RNOR or REXP in your main, insert
15 zigset(86947731 );
16 with your own choice of seed value>0, rather t
17 (If you do not invoke zigset(...) you will get
18 For details of the method, see Marsaglia and T
19 for generating random variables", Journ. Stati
20
21 */
22
23
24 #ifndef RandGaussZiggurat_h
25 #define RandGaussZiggurat_h 1
26
27 #include "cmath"
28 #include "CLHEP/Random/RandGauss.h"
29 #include "CLHEP/Utility/thread_local.h"
30
31 namespace CLHEP {
32
33 /**
34 * @author ATLAS
35 * @ingroup random
36 */
37 class RandGaussZiggurat : public RandGauss {
38
39 public:
40
41 inline RandGaussZiggurat ( HepRandomEngine&
42 inline RandGaussZiggurat ( HepRandomEngine*
43
44 // Destructor
45 virtual ~RandGaussZiggurat();
46
47 // Static methods to shoot random values usi
48
49 static inline float shoot() {return ziggurat
50 static inline float shoot( float mean, float
51
52 static void shootArray ( const int size, flo
53 static void shootArray ( const int size, dou
54
55 // Static methods to shoot random values us
56 // by-passing the static generator.
57
58 static inline float shoot( HepRandomEngine*
59 static inline float shoot( HepRandomEngine*
60
61 static void shootArray ( HepRandomEngine* an
62 static void shootArray ( HepRandomEngine* an
63
64 // Instance methods using the localEngine t
65 // generator, and the default mean and stdD
66
67 inline float fire() {return float(ziggurat_R
68
69 inline float fire ( float mean, float stdDev
70
71 void fireArray ( const int size, float* vec
72 void fireArray ( const int size, double* ve
73 void fireArray ( const int size, float* vec
74 void fireArray ( const int size, double* ve
75
76 virtual double operator()();
77 virtual double operator()( double mean, doub
78
79 // Save and restore to/from streams
80
81 std::ostream & put ( std::ostream & os ) con
82 std::istream & get ( std::istream & is );
83
84 std::string name() const;
85 HepRandomEngine & engine();
86
87 static std::string distributionName() {retur
88 // Provides the name of this distribution cl
89
90 static bool ziggurat_init();
91 protected:
92 //////////////////////////
93 // Ziggurat Original code:
94 //////////////////////////
95 //static unsigned long jz,jsr=123456789;
96 //
97 //#define SHR3 (jz=jsr, jsr^=(jsr<<13), jsr^
98 //#define UNI (.5 + (signed) SHR3*.2328306e-
99 //#define IUNI SHR3
100 //
101 //static long hz;
102 //static unsigned long iz, kn[128], ke[256];
103 //static float wn[128],fn[128], we[256],fe[2
104 //
105 //#define RNOR (hz=SHR3, iz=hz&127, (fabs(hz
106 //#define REXP (jz=SHR3, iz=jz&255, ( jz
107
108 static CLHEP_THREAD_LOCAL unsigned long kn[1
109 static CLHEP_THREAD_LOCAL float wn[128],fn[1
110
111 static CLHEP_THREAD_LOCAL bool ziggurat_is_i
112
113 static inline unsigned long ziggurat_SHR3(He
114 static inline float ziggurat_UNI(HepRandomEn
115 static inline float ziggurat_RNOR(HepRandomE
116 if(!ziggurat_is_init) ziggurat_init();
117 long hz=(signed)ziggurat_SHR3(anEngine);
118 unsigned long iz=hz&127;
119 return ((unsigned long)std::abs(hz)<kn[iz]
120 }
121 static float ziggurat_nfix(long hz,HepRandom
122
123 private:
124
125 // Private copy constructor. Defining it her
126 RandGaussZiggurat(const RandGaussZiggurat& d
127
128 // All the engine info, and the default mean
129 // base class.
130
131 };
132
133 } // namespace CLHEP
134
135 namespace CLHEP {
136
137 RandGaussZiggurat::RandGaussZiggurat(HepRandom
138 {
139 }
140
141 RandGaussZiggurat::RandGaussZiggurat(HepRandom
142 {
143 }
144
145 } // namespace CLHEP
146
147 #endif
148