TRandom.h

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// @(#)root/mathcore:$Id$
// Author: Rene Brun   15/12/95
 
/*************************************************************************
 * Copyright (C) 1995-2000, Rene Brun and Fons Rademakers.               *
 * All rights reserved.                                                  *
 *                                                                       *
 * For the licensing terms see $ROOTSYS/LICENSE.                         *
 * For the list of contributors see $ROOTSYS/README/CREDITS.             *
 *************************************************************************/
 
#ifndef ROOT_TRandom
#define ROOT_TRandom
 
#include "Math/TRandomEngine.h"
 
//////////////////////////////////////////////////////////////////////////
//                                                                      //
// TRandom                                                              //
//                                                                      //
// Simple prototype random number generator class (periodicity = 10**9) //
//                                                                      //
//////////////////////////////////////////////////////////////////////////
 
#include "TNamed.h"
#include <limits>
 
class TRandom : public TNamed, public ROOT::Math::TRandomEngine {
 
protected:
   UInt_t   fSeed;  //Random number generator seed
 
public:
   TRandom(UInt_t seed=65539);
   ~TRandom() override;
   virtual  Int_t    Binomial(Int_t ntot, Double_t prob);
   virtual  Double_t BreitWigner(Double_t mean=0, Double_t gamma=1);
   virtual  void     Circle(Double_t &x, Double_t &y, Double_t r);
   virtual  Double_t Exp(Double_t tau);
   virtual  Double_t Gaus(Double_t mean=0, Double_t sigma=1);
   virtual  UInt_t   GetSeed() const;
   virtual  UInt_t   Integer(UInt_t imax);
   virtual  Double_t Landau(Double_t mean=0, Double_t sigma=1);
   virtual ULong64_t Poisson(Double_t mean);
   virtual  Double_t PoissonD(Double_t mean);
   virtual  void     Rannor(Float_t &a, Float_t &b);
   virtual  void     Rannor(Double_t &a, Double_t &b);
   virtual  void     ReadRandom(const char *filename);
   virtual  void     SetSeed(ULong_t seed=0);
    Double_t Rndm() override;
   // keep for backward compatibility
   virtual  Double_t Rndm(Int_t ) { return Rndm(); }
   virtual  void     RndmArray(Int_t n, Float_t *array);
   virtual  void     RndmArray(Int_t n, Double_t *array);
   virtual  void     Sphere(Double_t &x, Double_t &y, Double_t &z, Double_t r);
   virtual  Double_t Uniform(Double_t x1=1);
   virtual  Double_t Uniform(Double_t x1, Double_t x2);
   virtual  void     WriteRandom(const char *filename) const;
 
   // std::UniformRandomBitGenerator interface -- makes TRandom usable directly
   // with std::shuffle, std::uniform_int_distribution and similar.
   using result_type = UInt_t;
   static constexpr result_type min() { return 0; }
   static constexpr result_type max() { return std::numeric_limits<UInt_t>::max(); }
   /// \note Rndm() returns a double in ]0,1[, so converting back to UInt_t
   ///   has a small precision loss. Subclasses with access to raw integer output
   ///   should override this for better accuracy.
   virtual result_type operator()() { return static_cast<result_type>(Rndm() * (static_cast<double>(max()) + 1.0)); }
 
   ClassDefOverride(TRandom,3)  //Simple Random number generator (periodicity = 10**9)
};
 
R__EXTERN TRandom *gRandom;
 
#endif