| Geant4 Cross Reference |
1 // -*- C++ -*-
2 //
3 // -----------------------------------------------------------------------
4 // HEP Random
5 // --- Ranlux64Engine ---
6 // class header file
7 // -----------------------------------------------------------------------
8 // The algorithm for this random engine has been taken from the notes of
9 // a double-precision ranlux implementation by Martin Luscher, dated
10 // November 1997.
11 //
12 // Like the previous ranlux generator, this one also has "luxury" levels,
13 // determining how many pseudo-random numbers are discarded for every
14 // twelve values used. Three levels are given, with the note that Luscher
15 // himself advocates only the highest two levels for this engine.
16 // level 0 (p=109): Throw away 109 values for every 12 used
17 // level 1 (p=202): (default) Throw away 202 values for every 12 used
18 // level 2 (p=397): Throw away 397 values for every 12 used
19 //
20 // The initialization is carried out using a Multiplicative Congruential
21 // generator using formula constants of L'Ecuyer as described in "F.James,
22 // Comp. Phys. Comm. 60 (1990) 329-344".
23 // =======================================================================
24 // Ken Smith - Created Initial draft: 14th Jul 1998
25 // - Added conversion operators: 6th Aug 1998
26 // Mark Fischler
27 // 9/9/98 - Added update() routine to allow computation of many at once
28 // - Replaced algorithm with jone exactly matching Luscher:
29 // 48-bits generated
30 // skip n-12 instead of n numbers
31 // - Corrected protection agains overflow
32 // 12/8/04 - Methods for instance save/restore
33 // 12/27/04 - methods for anonymous save/restore 12/27/04
34 //
35 // =======================================================================
36
37 #ifndef Ranlux64Engine_h
38 #define Ranlux64Engine_h
39
40 #include "CLHEP/Random/RandomEngine.h"
41
42 namespace CLHEP {
43
44 /**
45 * @author
46 * @ingroup random
47 */
48 class Ranlux64Engine : public HepRandomEngine {
49
50 public:
51
52 Ranlux64Engine( std::istream& is );
53 Ranlux64Engine();
54 Ranlux64Engine( long seed, int lxr = 1 );
55 Ranlux64Engine( int rowIndex, int colIndex, int lxr );
56 virtual ~Ranlux64Engine();
57 // Constructors and destructor
58
59 double flat();
60 // It returns a pseudo random number between 0 and 1,
61 // excluding the end points.
62
63 void flatArray (const int size, double* vect);
64 // Fills the array "vect" of specified size with flat random values.
65
66 void setSeed(long seed, int lxr=1);
67 // Sets the state of the algorithm according to seed.
68
69 void setSeeds(const long * seeds, int lxr=1);
70 // Sets the state of the algorithm according to the zero terminated
71 // array of seeds. Only the first seed is used.
72
73 void saveStatus( const char filename[] = "Ranlux64.conf" ) const;
74 // Saves in named file the current engine status.
75
76 void restoreStatus( const char filename[] = "Ranlux64.conf" );
77 // Reads from named file the last saved engine status and restores it.
78
79 void showStatus() const;
80 // Dumps the engine status on the screen.
81
82 int getLuxury() const { return luxury; }
83 // Gets the luxury level.
84
85 virtual std::ostream & put (std::ostream & os) const;
86 virtual std::istream & get (std::istream & is);
87 static std::string beginTag ( );
88 virtual std::istream & getState ( std::istream & is );
89
90 std::string name() const;
91 static std::string engineName() {return "Ranlux64Engine";}
92
93 std::vector<unsigned long> put () const;
94 bool get (const std::vector<unsigned long> & v);
95 bool getState (const std::vector<unsigned long> & v);
96
97 static const unsigned int VECTOR_STATE_SIZE = 30;
98
99 private:
100
101 void update();
102 void advance(int dozens);
103
104 int pDiscard; // separate sequence by p-r = p-12 discarded elements
105 int pDozens; // pDiscard / 12;
106 int endIters; // pDiscard % 12;
107 int luxury;
108
109 int index;
110 double randoms[12]; // randoms [i] is the x[n-i] of Luscher's note
111 double carry;
112
113 }; // Ranlux64Engine
114
115 } // namespace CLHEP
116
117 #endif // Ranlux64Engine_h
118