CLHEP/Random/MTwistEngine.h
// $Id: MTwistEngine.h,v 1.5 2000/04/17 22:59:46 mf Exp $
// -*- C++ -*-
//
// -----------------------------------------------------------------------
// HEP Random
// --- MTwistEngine ---
// class header file
// -----------------------------------------------------------------------
// A "fast, compact, huge-period generator" based on M. Matsumoto and
// T. Nishimura, "Mersenne Twister: A 623-dimensionally equidistributed
// uniform pseudorandom number generator", to appear in ACM Trans. on
// Modeling and Computer Simulation. It is a twisted GFSR generator
// with a Mersenne-prime period of 2^19937-1, uniform on open interval (0,1)
// For further information, see http://www.math.keio.ac.jp/~matumoto/emt.html
// =======================================================================
// Ken Smith - Started initial draft: 14th Jul 1998
// - Optimized to get pow() out of flat() method: 21st Jul
// - Added conversion operators: 6th Aug 1998
// M Fischler - Changes in way powers of two are kept: 16-Sep-1998
// =======================================================================
#ifndef MTwistEngine_h
#define MTwistEngine_h
#include "CLHEP/Random/RandomEngine.h"
class MTwistEngine : public HepRandomEngine {
public:
MTwistEngine();
MTwistEngine( long seed );
MTwistEngine( HepInt rowIndex, HepInt colIndex );
MTwistEngine( HepStd::istream & is );
virtual ~MTwistEngine();
// Constructors and destructor.
MTwistEngine( const MTwistEngine & p );
MTwistEngine & operator=( const MTwistEngine & 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. It is allowed to ignore one or many seeds in this array.
void saveStatus( const char filename[] = "MTwist.conf") const;
// Saves the current engine status in the named file
void restoreStatus( const char filename[] = "MTwist.conf" );
// Reads from named file the the last saved engine status and restores it.
void showStatus() const;
// Dumps the current engine status on the screen.
operator HepFloat(); // returns flat, without worrying about filling bits
operator unsigned int(); // 32-bit flat, quickest of all
friend HepStd::ostream & operator<< (HepStd::ostream & os, const MTwistEngine & e);
friend HepStd::istream & operator>> (HepStd::istream & is, MTwistEngine & e);
private:
unsigned int mt[624];
HepInt count624;
static HepDouble twoToMinus_32;
static HepDouble twoToMinus_53;
static HepDouble nearlyTwoToMinus_54;
void powersOfTwo();
enum{ NminusM = 227, M = 397, N = 624};
static HepInt numEngines;
static HepInt maxIndex;
}; // MTwistEngine
#endif // MTwistEngine_h
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