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MTwistEngine.h
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1 // $Id:$
2 // -*- C++ -*-
3 //
4 // -----------------------------------------------------------------------
5 // HEP Random
6 // --- MTwistEngine ---
7 // class header file
8 // -----------------------------------------------------------------------
9 // A "fast, compact, huge-period generator" based on M. Matsumoto and
10 // T. Nishimura, "Mersenne Twister: A 623-dimensionally equidistributed
11 // uniform pseudorandom number generator", to appear in ACM Trans. on
12 // Modeling and Computer Simulation. It is a twisted GFSR generator
13 // with a Mersenne-prime period of 2^19937-1, uniform on open interval (0,1)
14 // For further information, see http://www.math.keio.ac.jp/~matumoto/emt.html
15 // =======================================================================
16 // Ken Smith - Started initial draft: 14th Jul 1998
17 // - Optimized to get pow() out of flat() method: 21st Jul
18 // - Added conversion operators: 6th Aug 1998
19 // M Fischler - Changes in way powers of two are kept: 16-Sep-1998
20 // Mark Fischler - Methods for distrib. instance save/restore 12/8/04
21 // Mark Fischler methods for anonymous save/restore 12/27/04
22 // =======================================================================
23 
24 #ifndef MTwistEngine_h
25 #define MTwistEngine_h
26 
27 #include "CLHEP/Random/RandomEngine.h"
28 
29 namespace CLHEP {
30 
35 class MTwistEngine : public HepRandomEngine {
36 
37 public:
38 
39  MTwistEngine();
40  MTwistEngine( long seed );
41  MTwistEngine( int rowIndex, int colIndex );
42  MTwistEngine( std::istream & is );
43  virtual ~MTwistEngine();
44  // Constructors and destructor.
45 
46  double flat();
47  // Returns a pseudo random number between 0 and 1 (excluding the end points).
48 
49  void flatArray(const int size, double* vect);
50  // Fills an array "vect" of specified size with flat random values.
51 
52  void setSeed(long seed, int);
53  // Sets the state of the algorithm according to seed.
54 
55  void setSeeds(const long * seeds, int);
56  // Sets the state of the algorithm according to the zero terminated
57  // array of seeds. It is allowed to ignore one or many seeds in this array.
58 
59  void saveStatus( const char filename[] = "MTwist.conf") const;
60  // Saves the current engine status in the named file
61 
62  void restoreStatus( const char filename[] = "MTwist.conf" );
63  // Reads from named file the the last saved engine status and restores it.
64 
65  void showStatus() const;
66  // Dumps the current engine status on the screen.
67 
68  operator float(); // returns flat, without worrying about filling bits
69  operator unsigned int(); // 32-bit flat, quickest of all
70 
71  virtual std::ostream & put (std::ostream & os) const;
72  virtual std::istream & get (std::istream & is);
73  static std::string beginTag ( );
74  virtual std::istream & getState ( std::istream & is );
75 
76  std::string name() const;
77  static std::string engineName() {return "MTwistEngine";}
78 
79  std::vector<unsigned long> put () const;
80  bool get (const std::vector<unsigned long> & v);
81  bool getState (const std::vector<unsigned long> & v);
82 
83  static const unsigned int VECTOR_STATE_SIZE = 626;
84 
85 private:
86 
87  unsigned int mt[624];
88  int count624;
89 
90  enum{ NminusM = 227, M = 397, N = 624};
91  static int numEngines;
92  static int maxIndex;
93 
94 }; // MTwistEngine
95 
96 } // namespace CLHEP
97 
98 #endif // MTwistEngine_h
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