| Geant4 Cross Reference |
1 // -*- C++ -*-
2 //
3 // -----------------------------------------------------------------------
4 // HEP Random
5 // --- RandLandau ---
6 // class header file
7 // -----------------------------------------------------------------------
8 // This file is part of Geant4 (simulation toolkit for HEP).
9
10 // Class defining methods for shooting or firing Landau distributed
11 // random values.
12 //
13 // The Landau distribution is parameterless and describes the fluctuations
14 // in energy loss of a particle, making certain assumptions. For
15 // definitions and algorithms, the following papers could be read:
16 //
17 // Landau, Jour Phys VIII, No. 4, p. 201 (1944)
18 // Borsh-Supan, Jour Res. of NBS 65B NO. 4 p. 245 (1961)
19 // Kolbig & Schorr Comp Phys Comm 31 p. 97 (1984)
20 //
21 // The algorithm implemented comes form RANLAN in CERNLIB.
22
23 // =======================================================================
24 // M. Fischler - Created: 5th January 2000
25 // M Fischler - put and get to/from streams 12/10/04
26 //
27 // =======================================================================
28
29 #ifndef RandLandau_h
30 #define RandLandau_h 1
31
32 #include "CLHEP/Random/Random.h"
33 #include "CLHEP/Utility/memory.h"
34
35 namespace CLHEP {
36
37 /**
38 * @author
39 * @ingroup random
40 */
41 class RandLandau : public HepRandom {
42
43 public:
44
45 inline RandLandau ( HepRandomEngine& anEngine );
46 inline RandLandau ( HepRandomEngine* anEngine );
47
48 // These constructors should be used to instantiate a RandLandau
49 // distribution object defining a local engine for it.
50 // The static generator will be skipped using the non-static methods
51 // defined below.
52 // If the engine is passed by pointer the corresponding engine object
53 // will be deleted by the RandLandau destructor.
54 // If the engine is passed by reference the corresponding engine object
55 // will not be deleted by the RandLandau destructor.
56
57 virtual ~RandLandau();
58 // Destructor
59
60 // Save and restore to/from streams
61
62 std::ostream & put ( std::ostream & os ) const;
63 std::istream & get ( std::istream & is );
64
65 //
66 // Methods to generate Landau-distributed random deviates.
67 //
68 // These deviates are accurate to the actual Landau distribution to
69 // one part in 10**5 or better.
70
71 // Static methods to shoot random values using the static generator
72
73 static inline double shoot();
74
75 static void shootArray ( const int size, double* vect );
76
77 // Static methods to shoot random values using a given engine
78 // by-passing the static generator.
79
80 static inline double shoot( HepRandomEngine* anotherEngine );
81
82 static void shootArray ( HepRandomEngine* anotherEngine,
83 const int size,
84 double* vect );
85
86 // Instance methods using the localEngine to instead of the static
87 // generator, and the default mean and stdDev established at construction
88
89 inline double fire();
90
91 void fireArray ( const int size, double* vect);
92
93 inline double operator()();
94
95 std::string name() const;
96 HepRandomEngine & engine();
97
98 static std::string distributionName() {return "RandLandau";}
99 // Provides the name of this distribution class
100
101
102 protected:
103
104 static double transform (double r);
105 static double transformSmall (double r);
106
107 private:
108
109 std::shared_ptr<HepRandomEngine> localEngine;
110
111 };
112
113 } // namespace CLHEP
114
115 #include "CLHEP/Random/RandLandau.icc"
116
117 #endif
118