CLHEP/Random/RanluxEngine.h

// $Id: RanluxEngine.h,v 1.9 2000/04/17 23:00:37 mf Exp $
// -*- C++ -*-
//
// -----------------------------------------------------------------------
//                             HEP Random
//                        --- RanluxEngine ---
//                          class header file
// -----------------------------------------------------------------------
// This file is part of Geant4 (simulation toolkit for HEP).
//
// The algorithm for this random engine has been taken from the original
// implementation in FORTRAN by Fred James as part of the MATHLIB HEP
// library.
// The initialisation is carried out using a Multiplicative Congruential
// generator using formula constants of L'Ecuyer as described in "F.James,
// Comp. Phys. Comm. 60 (1990) 329-344".

// =======================================================================
// Adeyemi Adesanya - Created: 6th November 1995
// Gabriele Cosmo - Adapted & Revised: 22nd November 1995
// Adeyemi Adesanya - Added setSeeds() method: 2nd February 1996
// Gabriele Cosmo - Added flatArray() method: 8th February 1996
//                - Added methods for engine status: 19th November 1996
//                - Added default luxury value for setSeed()
//                  and setSeeds(): 21st July 1997
// J.Marraffino   - Added stream operators and related constructor.
//                  Added automatic seed selection from seed table and
//                  engine counter: 14th Feb 1998
// Ken Smith      - Added conversion operators:  6th Aug 1998
// =======================================================================

#ifndef RanluxEngine_h
#define RanluxEngine_h 1

#include "CLHEP/Random/RandomEngine.h"

class RanluxEngine : public HepRandomEngine {

public:

  RanluxEngine( HepStd::istream& is );
  RanluxEngine();
  RanluxEngine( long seed, HepInt lux = 3 );
  RanluxEngine( HepInt rowIndex, HepInt colIndex, HepInt lux );
  virtual ~RanluxEngine();
  // Constructors and destructor

  RanluxEngine(const RanluxEngine &p);
  // Copy constructor

  RanluxEngine & operator = (const RanluxEngine &p);
  // Overloaded assignment operator, to retrieve the engine status.

// Luxury level is set in the same way as the original FORTRAN routine.
//  level 0  (p=24): equivalent to the original RCARRY of Marsaglia
//           and Zaman, very long period, but fails many tests.
//  level 1  (p=48): considerable improvement in quality over level 0,
//           now passes the gap test, but still fails spectral test.
//  level 2  (p=97): passes all known tests, but theoretically still
//           defective.
//  level 3  (p=223): DEFAULT VALUE.  Any theoretically possible
//           correlations have very small chance of being observed.
//  level 4  (p=389): highest possible luxury, all 24 bits chaotic.

  HepDouble flat();
  // It returns a pseudo random number between 0 and 1,
  // excluding the end points.

  void flatArray (const HepInt size, HepDouble* vect);
  // Fills the array "vect" of specified size with flat random values.

  void setSeed(long seed, HepInt lux=3);
  // Sets the state of the algorithm according to seed.

  void setSeeds(const long * seeds, HepInt lux=3);
  // Sets the state of the algorithm according to the zero terminated
  // array of seeds. Only the first seed is used.

  void saveStatus( const char filename[] = "Ranlux.conf" ) const;
  // Saves on file Ranlux.conf the current engine status.

  void restoreStatus( const char filename[] = "Ranlux.conf" );
  // Reads from file Ranlux.conf the last saved engine status
  // and restores it.

  void showStatus() const;
  // Dumps the engine status on the screen.

  HepInt getLuxury() const { return luxury; }
  // Gets the luxury level.

  operator unsigned int(); // 32-bit flat, but slower than double or float

  friend HepStd::ostream& operator<< (HepStd::ostream& os, const RanluxEngine& e);
  friend HepStd::istream& operator>> (HepStd::istream& is,       RanluxEngine& e);

private:

  HepInt nskip, luxury;
  HepFloat float_seed_table[24];
  HepInt i_lag,j_lag;  
  HepFloat carry;
  HepInt count24;
  const HepInt int_modulus;
  const HepDouble mantissa_bit_24;
  const HepDouble mantissa_bit_12;
  static HepInt numEngines;
  static HepInt maxIndex;
};

#endif