RWRandGenMTwist

Module:  Essential Math   Group:  Statistics classes

Does not inherit

• Local Index
• Synopsis
• Description
• Public Constructors
• Public Member Functions
• Public Member Operators
• Related Global Operator

Members

long seed() operator!=() operator()

operator=() operator==() printOn()

restart() restoreFrom() RWRandGenMTwist()

saveOn() scanFrom()

Non-Members

operator>>()

operator<<()

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

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 following sources:

1. The original Arcticle
   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, Januray pp.3-30 1998

2. The Mersenne Twister Website
   http://www.math.keio.ac.jp/~matumoto/emt.html

RWRandGenMTwist();

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

RWRandGenMTwist(const RWRandGenMTwist& x);

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

RWRandGenMTwist(unsigned long seed);

Constructs a generator with a specified seed.

unsigned 
long seed() const;

Returns the seed used to initialize the generator.

void 
restart();

Restarts the generator, abitrarily seeding it by a call to the time function.

void 
restart(unsigned long seed);

Restarts the generator with specified seed.

double 
operator()();

Returns a random double in [0,1].

void 
operator=(const RWRandGenMTwist& x);

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

bool 
operator==(const RWRandGenMTwist& x) const;

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

bool 
operator!=(const RWRandGenMTwist& x) const;

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

void
printOn(std::ostream& s) const; 

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

void
scanFrom(std::istream& s);

Inputs an internal state from istream s to self.

void
restoreFrom(RWvistream&);
void
restoreFrom(RWFile&);

Restores internal state of self from a virtual stream or an RWFile.

void
saveOn(RWvostream&) const;
void
saveOn(RWFile&) const;

Stores internal state of self to a virtual stream or in a binary format to an RWFile or RWvostream.

std::ostream& rwmathexport
operator<< (std::ostream& s, const RWRandGenMTwist& rgen);

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

std::istream& rwmathexport
operator>> (std::istream& s, RWRandGenMTwist& rgen);

Inputs an internal state from istream s to rgen.

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