umontreal.iro.lecuyer.rng

Class MT19937

java.lang.Object

umontreal.iro.lecuyer.rng.RandomStreamBase

umontreal.iro.lecuyer.rng.MT19937

All Implemented Interfaces:

java.io.Serializable, java.lang.Cloneable, CloneableRandomStream, RandomStream

public class MT19937
extends RandomStreamBase

Implements the RandomStream interface via inheritance from RandomStreamBase. The backbone generator is the MT19937 Mersenne Twister, proposed by Matsumoto and Nishimura, which has a state size of 19937 bits and a period length of approximatively 2¹⁹⁹³⁷. Each instance uses another CloneableRandomStream to fill its initial state. With this design, the initial states of successive streams are not spaced by an equal number of steps, and there is no guarantee that different streams do not overlap, but damaging overlap is unlikely because of the huge size of the state space. The seed of the RNG, and the state of a stream at any given step, is a 624-dimensional vector of 32-bit integers. The output of nextValue has 32 bits of precision.

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
MT19937(CloneableRandomStream rng) Constructs a new stream, using rng to fill its initial state.
MT19937(CloneableRandomStream rng, java.lang.String name) Constructs a new stream with the identifier name (used in the toString method).

Method Summary

Modifier and Type	Method and Description
MT19937	clone() Clones the current generator and return its copy.
void	resetNextSubstream() Reinitializes the stream to the beginning of its next substream: Ng is computed, and Cg and Bg are set to Ng.
void	resetStartStream() Reinitializes the stream to its initial state Ig: Cg and Bg are set to Ig.
void	resetStartSubstream() Reinitializes the stream to the beginning of its current substream: Cg is set to Bg.
java.lang.String	toString() Returns a string containing the current state of this stream.

Methods inherited from class umontreal.iro.lecuyer.rng.RandomStreamBase

formatState, formatStateFull, increasedPrecision, nextArrayOfDouble, nextArrayOfInt, nextDouble, nextInt

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

MT19937

public MT19937(CloneableRandomStream rng)

Constructs a new stream, using rng to fill its initial state.

Parameters:

rng - used to build the seed

MT19937

public MT19937(CloneableRandomStream rng,
               java.lang.String name)

Constructs a new stream with the identifier name (used in the toString method).

Parameters:

rng - used to build the seed

name - name of the stream

Method Detail

clone

public MT19937 clone()

Clones the current generator and return its copy.

Specified by:

clone in interface CloneableRandomStream

Overrides:

clone in class RandomStreamBase

Returns:

A deep copy of the current generator

resetStartStream

public void resetStartStream()

Description copied from interface: RandomStream

Reinitializes the stream to its initial state I_g: C_g and B_g are set to I_g.

Specified by:

resetStartStream in interface RandomStream

Specified by:

resetStartStream in class RandomStreamBase

resetStartSubstream

public void resetStartSubstream()

Description copied from interface: RandomStream

Reinitializes the stream to the beginning of its current substream: C_g is set to B_g.

Specified by:

resetStartSubstream in interface RandomStream

Specified by:

resetStartSubstream in class RandomStreamBase

resetNextSubstream

public void resetNextSubstream()

Description copied from interface: RandomStream

Reinitializes the stream to the beginning of its next substream: N_g is computed, and C_g and B_g are set to N_g.

Specified by:

resetNextSubstream in interface RandomStream

Specified by:

resetNextSubstream in class RandomStreamBase

toString

public java.lang.String toString()

Description copied from interface: RandomStream

Returns a string containing the current state of this stream.

Specified by:

toString in interface RandomStream

Specified by:

toString in class RandomStreamBase

Returns:

the state of the generator formated as a string