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:

UNKNOWN

Date Reviewed:

before2004/08/25

Prerequisite

• A knowledge of C++, in particular inheritance
• College level mathematics

Etymology

MLCG stands for "Multiplicative Linear Congruential Generator"

Synopsis

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;

Example

Thrown Exceptions

• AipsError: If a programming error or unexpected numeric size is detected. Should not occur in normal usage.

To Do

• Nothing I hope!

Definition at line 306 of file Random.h.

Constructor & Destructor Documentation

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

explicit

The constructor allows you to specify seeds.

virtual casacore::MLCG::~MLCG ( )

virtual

The destructor is trivial.

Member Function Documentation

virtual uInt casacore::MLCG::asuInt ( )

virtual

Return the 32-random bits as an unsigned integer.

Implements casacore::RNG.

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

inline

Definition at line 363 of file Random.h.

References itsInitSeedOne, itsInitSeedTwo, and reset().

virtual void casacore::MLCG::reset ( )

virtual

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

inline

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 341 of file Random.h.

References itsSeedOne.

void casacore::MLCG::seed1 ( Int  s )

inline

Definition at line 346 of file Random.h.

References itsInitSeedOne, and reset().

Int casacore::MLCG::seed2 ( ) const

inline

Definition at line 352 of file Random.h.

References itsSeedTwo.

void casacore::MLCG::seed2 ( Int  s )

inline

Definition at line 357 of file Random.h.

References itsInitSeedTwo, and reset().

Member Data Documentation

Int casacore::MLCG::itsInitSeedOne

private

Definition at line 335 of file Random.h.

Referenced by reseed(), and seed1().

Int casacore::MLCG::itsInitSeedTwo

private

Definition at line 336 of file Random.h.

Referenced by reseed(), and seed2().

Int casacore::MLCG::itsSeedOne

private

Definition at line 337 of file Random.h.

Referenced by seed1().

Int casacore::MLCG::itsSeedTwo

private

Definition at line 338 of file Random.h.

Referenced by seed2().

---

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

• casa/BasicMath/Random.h