| Geant4 Cross Reference |
1 // -*- C++ -*- 1
2 //
3 // -------------------------------------------
4 // HEP Random
5 // --- HepStat ---
6 // Purely static class containing use
7
8 // -------------------------------------------
9
10 // HepStat is a substitute for using a namespa
11 // One would never instantiate a HepStat objec
12 // usage of any of these methods looks like --
13 //
14 // double x = HepStat::erf ( .1 );
15 //
16 // A user may wish to improve the readability
17 // one method many times by lines like using H
18 //
19 // and later, x = erf(u); will work.
20 //
21
22 // These methods are implemented in separate .
23 // user code need pull in only the code that i
24 // (ROUGH estimates in cycles) and table footp
25 // in this header.
26
27
28 // ===========================================
29 // M. Fischler - Created: 1/25/00
30 //
31 // M. Fischler - Inserted flatToGaussian 1/
32 // From code of an attempt to speed u
33 // by use of tables and splines. The
34 // significantly faster than Box-
35 // algorithm is left as the RandG
36 // - Inserted inverseErf
37 // M. Fischler - Inserted gammln 2/4/00
38 // M. Fischler - Made constructor private;
39 // ===========================================
40
41 #ifndef HepStat_h
42 #define HepStat_h 1
43
44 namespace CLHEP {
45
46 /**
47 * @author
48 * @ingroup random
49 */
50 class HepStat {
51
52 private:
53 HepStat();
54 // You CANNOT instantiate a HepStat object.
55
56 public:
57
58 static double flatToGaussian (double r);
59 // This is defined by the satement that if
60 // on (0,1) then flatToGaussian(e()) is dis
61 // Gaussian. That is, flatToGaussian is th
62 // a Gaussian.
63 // Footprint: 30 K // Time: 150 cycl
64
65 static double inverseErf (double t);
66 static double erf (double x);
67 // defined in flatToGaussian.cc
68
69 static double erfQ (double x);
70 // Quicker, and with less footprint, than er
71 // but only accurate to 7 digits.
72 // Footprint: 0 // Time:
73
74 static double gammln (double x);
75 // ln (gamma(x))
76
77 };
78
79 } // namespace CLHEP
80
81 #endif
82