| Geant4 Cross Reference |
1 #include "CLHEP/Random/DoubConv.h"
2
3 #include "CLHEP/Random/RandExpZiggurat.h"
4
5 #include <cmath> // for std::log()
6 #include <iostream>
7 #include <vector>
8
9 namespace CLHEP {
10
11 CLHEP_THREAD_LOCAL unsigned long RandExpZiggurat::kn[128], RandExpZiggurat::ke[256];
12 CLHEP_THREAD_LOCAL float RandExpZiggurat::wn[128],RandExpZiggurat::fn[128],RandExpZiggurat::we[256],RandExpZiggurat::fe[256];
13 CLHEP_THREAD_LOCAL bool RandExpZiggurat::ziggurat_is_init = false;
14
15 std::string RandExpZiggurat::name() const {return "RandExpZiggurat";}
16
17 HepRandomEngine & RandExpZiggurat::engine() {return *localEngine;}
18
19 RandExpZiggurat::~RandExpZiggurat() {
20 }
21
22 RandExpZiggurat::RandExpZiggurat(const RandExpZiggurat& right) : HepRandom(right),defaultMean(right.defaultMean)
23 {
24 }
25
26 double RandExpZiggurat::operator()()
27 {
28 return fire( defaultMean );
29 }
30
31 void RandExpZiggurat::shootArray( const int size, float* vect, float mean )
32 {
33 for (int i=0; i<size; ++i) vect[i] = shoot(mean);
34 }
35
36 void RandExpZiggurat::shootArray( const int size, double* vect, double mean )
37 {
38 for (int i=0; i<size; ++i) vect[i] = shoot(mean);
39 }
40
41 void RandExpZiggurat::shootArray(HepRandomEngine* anEngine, const int size, float* vect, float mean )
42 {
43 for (int i=0; i<size; ++i) vect[i] = shoot(anEngine, mean);
44 }
45
46 void RandExpZiggurat::shootArray(HepRandomEngine* anEngine, const int size, double* vect, double mean )
47 {
48 for (int i=0; i<size; ++i) vect[i] = shoot(anEngine, mean);
49 }
50
51 void RandExpZiggurat::fireArray( const int size, float* vect)
52 {
53 for (int i=0; i<size; ++i) vect[i] = fire( defaultMean );
54 }
55
56 void RandExpZiggurat::fireArray( const int size, double* vect)
57 {
58 for (int i=0; i<size; ++i) vect[i] = fire( defaultMean );
59 }
60
61 void RandExpZiggurat::fireArray( const int size, float* vect, float mean )
62 {
63 for (int i=0; i<size; ++i) vect[i] = fire( mean );
64 }
65
66 void RandExpZiggurat::fireArray( const int size, double* vect, double mean )
67 {
68 for (int i=0; i<size; ++i) vect[i] = fire( mean );
69 }
70
71 std::ostream & RandExpZiggurat::put ( std::ostream & os ) const {
72 int pr=os.precision(20);
73 std::vector<unsigned long> t(2);
74 os << " " << name() << "\n";
75 os << "Uvec" << "\n";
76 t = DoubConv::dto2longs(defaultMean);
77 os << defaultMean << " " << t[0] << " " << t[1] << "\n";
78 os.precision(pr);
79 return os;
80 #ifdef REMOVED
81 int pr=os.precision(20);
82 os << " " << name() << "\n";
83 os << defaultMean << "\n";
84 os.precision(pr);
85 return os;
86 #endif
87 }
88
89 std::istream & RandExpZiggurat::get ( std::istream & is ) {
90 std::string inName;
91 is >> inName;
92 if (inName != name()) {
93 is.clear(std::ios::badbit | is.rdstate());
94 std::cerr << "Mismatch when expecting to read state of a "
95 << name() << " distribution\n"
96 << "Name found was " << inName
97 << "\nistream is left in the badbit state\n";
98 return is;
99 }
100 if (possibleKeywordInput(is, "Uvec", defaultMean)) {
101 std::vector<unsigned long> t(2);
102 is >> defaultMean >> t[0] >> t[1]; defaultMean = DoubConv::longs2double(t);
103 return is;
104 }
105 // is >> defaultMean encompassed by possibleKeywordInput
106 return is;
107 }
108
109
110 float RandExpZiggurat::ziggurat_efix(unsigned long jz,HepRandomEngine* anEngine)
111 {
112 if(!ziggurat_is_init) ziggurat_init();
113
114 unsigned long iz=jz&255;
115
116 float x;
117 for(;;)
118 {
119 if(iz==0) return (7.69711-std::log(ziggurat_UNI(anEngine))); /* iz==0 */
120 x=jz*we[iz];
121 if( fe[iz]+ziggurat_UNI(anEngine)*(fe[iz-1]-fe[iz]) < std::exp(-x) ) return (x);
122
123 /* initiate, try to exit for(;;) loop */
124 jz=ziggurat_SHR3(anEngine);
125 iz=(jz&255);
126 if(jz<ke[iz]) return (jz*we[iz]);
127 }
128 }
129
130 bool RandExpZiggurat::ziggurat_init()
131 {
132 const double rzm1 = 2147483648.0, rzm2 = 4294967296.;
133 double dn=3.442619855899,tn=dn,vn=9.91256303526217e-3, q;
134 double de=7.697117470131487, te=de, ve=3.949659822581572e-3;
135 int i;
136
137 /* Set up tables for RNOR */
138 q=vn/std::exp(-.5*dn*dn);
139 kn[0]=(unsigned long)((dn/q)*rzm1);
140 kn[1]=0;
141
142 wn[0]=q/rzm1;
143 wn[127]=dn/rzm1;
144
145 fn[0]=1.;
146 fn[127]=std::exp(-.5*dn*dn);
147
148 for(i=126;i>=1;i--) {
149 dn=std::sqrt(-2.*std::log(vn/dn+std::exp(-.5*dn*dn)));
150 kn[i+1]=(unsigned long)((dn/tn)*rzm1);
151 tn=dn;
152 fn[i]=std::exp(-.5*dn*dn);
153 wn[i]=dn/rzm1;
154 }
155
156 /* Set up tables for REXP */
157 q = ve/std::exp(-de);
158 ke[0]=(unsigned long)((de/q)*rzm2);
159 ke[1]=0;
160
161 we[0]=q/rzm2;
162 we[255]=de/rzm2;
163
164 fe[0]=1.;
165 fe[255]=std::exp(-de);
166
167 for(i=254;i>=1;i--) {
168 de=-std::log(ve/de+std::exp(-de));
169 ke[i+1]= (unsigned long)((de/te)*rzm2);
170 te=de;
171 fe[i]=std::exp(-de);
172 we[i]=de/rzm2;
173 }
174 ziggurat_is_init=true;
175 return true;
176 }
177
178 } // namespace CLHEP
179