RWRandGenMTwist Class Reference

Generates random numbers uniformly distributed over the interval [0, 1]. More...

#include <rw/randmtwist.h>

Public Member Functions
	RWRandGenMTwist ()
	RWRandGenMTwist (unsigned long seed)
	RWRandGenMTwist (const RWRandGenMTwist &u)
bool	operator!= (const RWRandGenMTwist &u) const
double	operator() ()
RWRandGenMTwist &	operator= (const RWRandGenMTwist &u)
bool	operator== (const RWRandGenMTwist &u) const
void	printOn (std::ostream &s) const
void	restart ()
void	restart (unsigned long seed)
void	restoreFrom (RWFile &)
void	restoreFrom (RWvistream &)
void	saveOn (RWFile &) const
void	saveOn (RWvostream &) const
void	scanFrom (std::istream &s)
unsigned long	seed () const

Related Functions
(Note that these are not member functions.)
std::ostream &	operator<< (std::ostream &s, const RWRandGenMTwist &gen)
std::istream &	operator>> (std::istream &s, RWRandGenMTwist &gen)

Detailed Description

Class RWRandGenMTwist generates random numbers uniformly distributed over the interval [0, 1], and may be used instead of class RWRandGenerator as a template parameter to any of the distribution generators derived from abstract base class RWTRand. RWRandGenMTwist uses Takuji Nishimura and Makoto Matsumoto's Mersenne Twister algorithm. It is relatively fast, and has a large period (2^19937-1).

Unlike class RWRandGenerator, each instance of RWRandGenMTwist contains and maintains its own, independent state. This can make it easier to use in some situations. The "internal state" of an instance of RWRandGenMTwist consists of a table of an unsigned long seed, an array of unsigned longs known as the "state vector" and an integer index into that state vector.

Additional information about the Mersenne Twister algorithm is available in the original article: M. Matsumoto and T. Nishimura,"Mersenne Twister: A 623-dimensionally equidistributed uniform pseudorandom number generator", ACM Trans. on Modeling and Computer Simulation Vol. 8, No. 1, January pp.3-30 1998. There are also numerous resources on the internet, including a website dedicated to the Mersenne Twister.

Synopsis

#include <rw/randmtwist.h>
RWRandGenMTwist gen;

Constructor & Destructor Documentation

RWRandGenMTwist::RWRandGenMTwist

(

)

Constructs a generator, arbitrarily seeded by a call to the time() function.

RWRandGenMTwist::RWRandGenMTwist

(

unsigned long

seed

)

Constructs a generator with a specified seed.

RWRandGenMTwist::RWRandGenMTwist

(

const RWRandGenMTwist &

u

)

Constructs a copy of u. The copy's state will equal the state of u at the time the copy is created, but will not share the state of u.

Member Function Documentation

bool RWRandGenMTwist::operator!=

(

const RWRandGenMTwist &

u

)

const

Returns true for two distinct instances of RWRandGenMTwist if their internal states differ. "(x != x)" returns false.

double RWRandGenMTwist::operator()

(

)

Returns a random double in [0,1].

RWRandGenMTwist& RWRandGenMTwist::operator=

(

const RWRandGenMTwist &

u

)

Sets an instance of RWRandGenMTwist equal to the state of instance u.

bool RWRandGenMTwist::operator==

(

const RWRandGenMTwist &

u

)

const

Returns true for two distinct instances of RWRandGenMTwist if they will return identical sequences of values.

void RWRandGenMTwist::printOn

(

std::ostream &

s

)

const

Outputs a summary of self's internal state on ostream s.

void RWRandGenMTwist::restart

(

)

Restarts the generator, arbitrarily seeding it by a call to the time() function.

void RWRandGenMTwist::restart

(

unsigned long

seed

)

Restarts the generator with specified seed.

void RWRandGenMTwist::restoreFrom

(

RWFile &

)

Restores internal state of self from an RWFile.

void RWRandGenMTwist::restoreFrom

(

RWvistream &

)

Restores internal state of self from a virtual stream.

void RWRandGenMTwist::saveOn

(

RWFile &

)

const

Stores internal state of self in a binary format to an RWFile.

void RWRandGenMTwist::saveOn

(

RWvostream &

)

const

Stores internal state of self to a virtual stream.

void RWRandGenMTwist::scanFrom

(

std::istream &

s

)

Inputs an internal state from istream s to self.

unsigned long RWRandGenMTwist::seed

(

)

const

Returns the seed used to initialize the generator.

Friends And Related Function Documentation

std::ostream & operator<< ( std::ostream &  s, const RWRandGenMTwist &  gen  )

related

Outputs a summary of gen's internal state on ostream s.

std::istream & operator>> ( std::istream &  s, RWRandGenMTwist &  gen  )

related

Inputs an internal state from istream s to gen.