CLHEP/Random/RanecuEngine.h

0001 // $Id: RanecuEngine.h,v 1.6 2010/07/20 18:06:02 garren Exp $
0002 // -*- C++ -*-
0003 //
0004 // -----------------------------------------------------------------------
0005 //                             HEP Random
0006 //                         --- RanecuEngine ---
0007 //                          class header file
0008 // -----------------------------------------------------------------------
0009 // This file is part of Geant4 (simulation toolkit for HEP).
0010 //
0011 // RANECU Random Engine - algorithm originally written in FORTRAN77
0012 //                        as part of the MATHLIB HEP library.
0013 // The initialisation is carried out using a Multiplicative Congruential
0014 // generator using formula constants of L'Ecuyer as described in "F.James,
0015 // Comp. Phys. Comm. 60 (1990) 329-344".
0016 // Seeds are taken from a seed table given an index, the getSeed() method
0017 // returns the current index in the seed table, the getSeeds() method
0018 // returns a pointer to the couple of seeds stored in the local table of
0019 // seeds at the current index.
0020
0021 // =======================================================================
0022 // Gabriele Cosmo - Created: 2nd February 1996
0023 //                - Minor corrections: 31st October 1996
0024 //                - Added methods for engine status: 19th November 1996
0025 //                - setSeed() now has default dummy argument
0026 //                  set to zero: 11th July 1997
0027 //                - Added default index to setSeeds(): 16th Oct 1997
0028 // J.Marraffino   - Added stream operators and related constructor.
0029 //                  Added automatic seed selection from seed table and
0030 //                  engine counter: 16th Feb 1998
0031 // Ken Smith      - Added conversion operators:  6th Aug 1998
0032 // Mark Fischler    Methods for distrib. instance save/restore 12/8/04
0033 // Mark Fischler    methods for anonymous save/restore 12/27/04
0034 // =======================================================================
0035
0036 #ifndef RanecuEngine_h
0037 #define RanecuEngine_h 1
0038
0039 #include "CLHEP/Random/defs.h"
0040 #include "CLHEP/Random/RandomEngine.h"
0041
0042 namespace CLHEP {
0043
0044 /**
0045  * @author <Gabriele.Cosmo@cern.ch>
0046  * @ingroup random
0047  */
0048 class RanecuEngine : public HepRandomEngine {
0049
0050 public:
0051
0052   RanecuEngine(std::istream& is);
0053   RanecuEngine();
0054   RanecuEngine(int index);
0055   virtual ~RanecuEngine();
0056   // Constructors and destructor.
0057
0058   double flat();
0059   // Returns a pseudo random number between 0 and 1
0060   // (excluding the end points)
0061
0062   void flatArray (const int size, double* vect);
0063   // Fills an array "vect" of specified size with flat random values.
0064
0065   void setIndex (long index);
0066   // Sets the state of the algorithm according to "index", the position
0067   // in the local table of seeds.
0068
0069   void setSeed (long index, int dum=0);
0070   // Resets the state of the algorithm according to "index", the position
0071   // in the static table of seeds stored in HepRandom.
0072
0073   void setSeeds (const long* seeds, int index=-1);
0074   // Sets the state of the algorithm according to the array of seeds
0075   // "seeds" containing two seed values to be stored in the local table at
0076   // "index" position.
0077
0078   void saveStatus( const char filename[] = "Ranecu.conf" ) const;
0079   // Saves on file Ranecu.conf the current engine status.
0080
0081   void restoreStatus( const char filename[] = "Ranecu.conf" );
0082   // Reads from file Ranecu.conf the last saved engine status
0083   // and restores it.
0084
0085   void showStatus() const;
0086   // Dumps the engine status on the screen.
0087
0088   operator double();
0089   // Returns same as flat()
0090   operator float();
0091   // less precise flat, faster if possible
0092   operator unsigned int();
0093   // 32-bit int flat, faster in this case
0094
0095   virtual std::ostream & put (std::ostream & os) const;
0096   virtual std::istream & get (std::istream & is);
0097   static  std::string beginTag ( );
0098   virtual std::istream & getState ( std::istream & is );
0099
0100   std::string name() const;
0101   static std::string engineName() {return "RanecuEngine";}
0102
0103   std::vector<unsigned long> put () const;
0104   bool get (const std::vector<unsigned long> & v);
0105   bool getState (const std::vector<unsigned long> & v);
0106
0107 protected:
0108
0109   // Suggested L'ecuyer coefficients for portable 32 bits generators.
0110
0111   static const int ecuyer_a = 40014;
0112   static const int ecuyer_b = 53668;
0113   static const int ecuyer_c = 12211;
0114   static const int ecuyer_d = 40692;
0115   static const int ecuyer_e = 52774;
0116   static const int ecuyer_f = 3791;
0117   static const int shift1   = 2147483563;
0118   static const int shift2   = 2147483399;
0119
0120   static const unsigned int VECTOR_STATE_SIZE = 4;
0121
0122 private:
0123
0124   // private method used to mitigate the effects of using a lookup table
0125   void further_randomize (int seq, int col, int index, int modulus);
0126
0127   // Members defining the current state of the generator.
0128
0129   static const int maxSeq = 215;
0130   long table[215][2];
0131   int seq;
0132
0133 };
0134
0135 }  // namespace CLHEP
0136
0137 #ifdef ENABLE_BACKWARDS_COMPATIBILITY
0138 //  backwards compatibility will be enabled ONLY in CLHEP 1.9
0139 using namespace CLHEP;
0140 #endif
0141
0142 #endif