CLHEP/Random/TripleRand.h
// $Id: TripleRand.h,v 1.6 2000/04/17 23:00:46 mf Exp $
// -*- C++ -*-
//
// -----------------------------------------------------------------------
// Hep Random
// --- TripleRand ---
// class header file
// -----------------------------------------------------------------------
// A canopy pseudo-random number generator. Using the Tausworthe
// exclusive-or shift register, a simple Integer Coungruence generator, and
// the Hurd 288 total bit shift register, all XOR'd with each other, we
// provide an engine that should be a fairly good "mother" generator.
//
// This is similar to DualRand, with the addition of the Hurd288Engine.
// From DualRand, we have the following:
// Exclusive or of a feedback shift register and integer congruence
// random number generator. The feedback shift register uses offsets
// 127 and 97. The integer congruence generator uses a different
// multiplier for each stream. The multipliers are chosen to give
// full period and maximum "potency" for modulo 2^32. The period of
// the combined random number generator is 2^159 - 2^32, and the
// sequences are different for each stream (not just started in a
// different place).
// The above is then amended to also add in the exclusive or of the
// 288-total bit Hurd engine which in this case is a series of 32
// interconnected 9-bit shift registers, with the newest bit of each register
// formed by the XOR of the previous bit and some bit b-d from a previous
// register where d is chosen to create a primitive polynomial to maximize
// the period.
// =======================================================================
// Ken Smith - Initial draft started: 23rd Jul 1998
// - Added conversion operators: 6th Aug 1998
// M Fischler - Big merge with CLHEP 13 May 1999
// - Elimination of unused Taus() and Cong() accessors
// =======================================================================
#ifndef TripleRand_h
#define TripleRand_h
#include "CLHEP/Random/RandomEngine.h"
#include "CLHEP/Random/Hurd288Engine.h"
class TripleRand: public HepRandomEngine {
public:
TripleRand();
TripleRand( long seed );
TripleRand( HepStd::istream & is );
TripleRand( HepInt rowIndex, HepInt colIndex );
virtual ~TripleRand();
// Constructors and destructor
TripleRand( const TripleRand & p );
TripleRand & operator=( const TripleRand & p );
// Copy constructor and operator=
HepDouble flat();
// Returns a pseudo random number between 0 and 1
// (excluding the end points)
void flatArray( const HepInt size, HepDouble * vect );
// Fills an array "vect" of specified size with flat random values.
void setSeed( long seed, HepInt );
// Sets the state of the algorithm according to seed.
void setSeeds( const long * seeds, HepInt );
// Sets the state of the algorithm according to the zero-terminated
// array of seeds.
void saveStatus( const char filename[] = "TripleRand.conf" ) const;
// Saves on named file the current engine status.
void restoreStatus( const char filename[] = "TripleRand.conf" );
// Reads from named file the last saved engine status and restores it.
void showStatus() const;
// Dumps the current engine status on the screen.
operator HepFloat(); // flat value, without worrying about filling bits
operator unsigned int(); // 32-bit flat value, quickest of all
friend HepStd::ostream & operator<<( HepStd::ostream & os, const TripleRand & e );
friend HepStd::istream & operator>>( HepStd::istream & is, TripleRand & e );
private:
static HepInt numEngines;
class Tausworthe {
public:
Tausworthe();
Tausworthe(unsigned int seed);
operator unsigned int();
void put( HepStd::ostream & os ) const;
void get( HepStd::istream & is );
private:
HepInt wordIndex;
unsigned int words[4];
}; // Tausworthe
class IntegerCong {
public:
IntegerCong();
IntegerCong(unsigned int seed, HepInt streamNumber);
operator unsigned int();
void put( HepStd::ostream & os ) const;
void get( HepStd::istream & is );
private:
unsigned int state, multiplier, addend;
}; // IntegerCong
static HepDouble twoToMinus_32;
static HepDouble twoToMinus_53;
static HepDouble nearlyTwoToMinus_54;
void powersOfTwo();
Hurd288Engine & Hurd(); // retrieve the constituent engine for input
const Tausworthe & ConstTaus() const; // Same as above
const IntegerCong & ConstCong() const; // necessary for
const Hurd288Engine & ConstHurd() const; // output
Tausworthe tausworthe; // Instances of each of the
IntegerCong integerCong; // three engines that combine to make
Hurd288Engine hurd; // one TripleRand instance
}; // TripleRand
#endif // TripleRand_h
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