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Reference Guide
LCGEngine.h
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1 // @(#)root/mathcore:$Id$
2 // Author: L. Moneta Tue Aug 4 2015
3 
4 /**********************************************************************
5  * *
6  * Copyright (c) 2015 LCG ROOT Math Team, CERN/PH-SFT *
7  * *
8  * *
9  **********************************************************************/
10 
11 // random engines based on ROOT
12 
13 #ifndef ROOT_Math_LCGEngine
14 #define ROOT_Math_LCGEngine
15 
16 #include <cassert>
17 #include <cstdint>
18 #include <string>
19 #include <vector>
20 
22 public:
23  virtual double Rndm() = 0;
24  virtual ~TRandomEngine() {}
25 };
26 
27 
28 namespace ROOT {
29 
30  namespace Math {
31 
32 
33  class LCGEngine : public TRandomEngine {
34 
35 
36  public:
37 
39  typedef uint32_t Result_t;
40  typedef uint32_t StateInt_t;
41 
42  LCGEngine() : fSeed(65539) { }
43 
44  virtual ~LCGEngine() {}
45 
46  void SetSeed(uint32_t seed) { fSeed = seed; }
47 
48  virtual double Rndm() {
49  //double Rndm() {
50  return Rndm_impl();
51  }
52  inline double operator() () { return Rndm_impl(); }
53 
54  uint32_t IntRndm() {
55  fSeed = (1103515245 * fSeed + 12345) & 0x7fffffffUL;
56  return fSeed;
57  }
58 
59  /// minimum integer taht can be generated
60  static unsigned int MinInt() { return 0; }
61  /// maximum integer taht can be generated
62  static unsigned int MaxInt() { return 0xffffffff; } // 2^32 -1
63  /// Size of the generator state
64  static int Size() { return 1; }
65  /// Name of the generator
66  static std::string Name() { return "LCGEngine"; }
67  protected:
68  // for testing all generators
69  void SetState(const std::vector<uint32_t> & state) {
70  assert(!state.empty());
71  fSeed = state[0];
72  }
73 
74  void GetState(std::vector<uint32_t> & state) {
75  state.resize(1);
76  state[0] = fSeed;
77  }
78  int Counter() const { return 0; }
79  private:
80 
81  double Rndm_impl() {
82  const double kCONS = 4.6566128730774E-10; // (1/pow(2,31)
83  unsigned int rndm = IntRndm(); // generate integer number
84  if (rndm != 0) return kCONS*rndm;
85  return Rndm_impl();
86  }
87 
88  uint32_t fSeed;
89  };
90 
91 
92  } // end namespace Math
93 
94 } // end namespace ROOT
95 
96 
97 #endif /* ROOT_Math_LCGEngine */
uint32_t IntRndm()
Definition: LCGEngine.h:54
Namespace for new ROOT classes and functions.
Definition: StringConv.hxx:21
virtual ~LCGEngine()
Definition: LCGEngine.h:44
virtual double Rndm()
Definition: LCGEngine.h:48
void GetState(std::vector< uint32_t > &state)
Definition: LCGEngine.h:74
void SetSeed(uint32_t seed)
Definition: LCGEngine.h:46
virtual double Rndm()=0
TRObject operator()(const T1 &t1) const
void SetState(const std::vector< uint32_t > &state)
Definition: LCGEngine.h:69
static int Size()
Size of the generator state.
Definition: LCGEngine.h:64
TRandomEngine BaseType
Definition: LCGEngine.h:38
static unsigned int MaxInt()
maximum integer taht can be generated
Definition: LCGEngine.h:62
virtual ~TRandomEngine()
Definition: LCGEngine.h:24
static unsigned int MinInt()
minimum integer taht can be generated
Definition: LCGEngine.h:60
Namespace for new Math classes and functions.
int Counter() const
Definition: LCGEngine.h:78
static std::string Name()
Name of the generator.
Definition: LCGEngine.h:66