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casacore::MLCG Class Reference

Multiplicative linear congruential generator. More...

#include <Random.h>

Inheritance diagram for casacore::MLCG:

Public Member Functions

 MLCG (Int seed1=0, Int seed2=1)
 The constructor allows you to specify seeds. More...
virtual ~MLCG ()
 The destructor is trivial. More...
virtual uInt asuInt ()
 Return the 32-random bits as an unsigned integer. More...
virtual void reset ()
 Resets the random number generator. More...
Int seed1 () const
 Functions that allow the user to retrieve or change the seed integers. More...
void seed1 (Int s)
Int seed2 () const
void seed2 (Int s)
void reseed (Int s1, Int s2)
- Public Member Functions inherited from casacore::RNG
virtual ~RNG ()
 A virtual destructor is needed to ensure that the destructor of derived classes gets used. More...
Float asFloat ()
 Return random bits converted to either a Float or a Double. More...
Double asDouble ()

Private Attributes

Int itsInitSeedOne
Int itsInitSeedTwo
Int itsSeedOne
Int itsSeedTwo

Detailed Description

Multiplicative linear congruential generator.

Intended use:

Public interface

Review Status

Reviewed By:
Date Reviewed:



MLCG stands for "Multiplicative Linear Congruential Generator"


The MLCG class implements a Multiplicative Linear Congruential Generator. In particular, it is an implementation of the double MLCG described in Efficient and Portable Combined Random Number Generators by Pierre L'Ecuyer, appearing in Communications of the ACM, Vol. 31. No. 6. This generator has a fairly long period, and has been statistically analyzed to show that it gives good inter-sample independence.

The constructor has two parameters, both of which are seeds for the generator. As in the ACG generator, both seeds are modified to give a "better" distribution of seed digits. Thus, you can safely use values such as 0 or 1 for the seeds. The MLCG generator used much less state than the ACG generator; only two integers (8 bytes) are needed for each generator.

Warning: This class assumes that the integer and unsigned integer type is exactly 32 bits long;


Thrown Exceptions

To Do

Definition at line 305 of file Random.h.

Constructor & Destructor Documentation

casacore::MLCG::MLCG ( Int  seed1 = 0,
Int  seed2 = 1 

The constructor allows you to specify seeds.

virtual casacore::MLCG::~MLCG ( )

The destructor is trivial.

Member Function Documentation

virtual uInt casacore::MLCG::asuInt ( )

Return the 32-random bits as an unsigned integer.

Implements casacore::RNG.

void casacore::MLCG::reseed ( Int  s1,
Int  s2 

Definition at line 362 of file Random.h.

References itsInitSeedOne, itsInitSeedTwo, and reset().

virtual void casacore::MLCG::reset ( )

Resets the random number generator.

After calling this function the random numbers generated will be the same as if the object had just been constructed.

Implements casacore::RNG.

Referenced by reseed(), seed1(), and seed2().

Int casacore::MLCG::seed1 ( ) const

Functions that allow the user to retrieve or change the seed integers.

The seeds returned are not the user supplied values but the values obtained after some deterministic modification to produce a more uniform bit distribution.

Definition at line 340 of file Random.h.

References itsSeedOne.

void casacore::MLCG::seed1 ( Int  s)

Definition at line 345 of file Random.h.

References itsInitSeedOne, and reset().

Int casacore::MLCG::seed2 ( ) const

Definition at line 351 of file Random.h.

References itsSeedTwo.

void casacore::MLCG::seed2 ( Int  s)

Definition at line 356 of file Random.h.

References itsInitSeedTwo, and reset().

Member Data Documentation

Int casacore::MLCG::itsInitSeedOne

Definition at line 334 of file Random.h.

Referenced by reseed(), and seed1().

Int casacore::MLCG::itsInitSeedTwo

Definition at line 335 of file Random.h.

Referenced by reseed(), and seed2().

Int casacore::MLCG::itsSeedOne

Definition at line 336 of file Random.h.

Referenced by seed1().

Int casacore::MLCG::itsSeedTwo

Definition at line 337 of file Random.h.

Referenced by seed2().

The documentation for this class was generated from the following file: