Package org.apache.commons.math.random

Class AbstractWell

java.lang.Object

org.apache.commons.math.random.BitsStreamGenerator

org.apache.commons.math.random.AbstractWell

All Implemented Interfaces:

java.io.Serializable, RandomGenerator

Direct Known Subclasses:

Well1024a, Well19937a, Well19937c, Well44497a, Well44497b, Well512a

public abstract class AbstractWell
extends BitsStreamGenerator
implements java.io.Serializable

This abstract class implements the WELL class of pseudo-random number generator from François Panneton, Pierre L'Ecuyer and Makoto Matsumoto.

This generator is described in a paper by François Panneton, Pierre L'Ecuyer and Makoto Matsumoto Improved Long-Period Generators Based on Linear Recurrences Modulo 2 ACM Transactions on Mathematical Software, 32, 1 (2006). The errata for the paper are in wellrng-errata.txt.

Since:

2.2

Version:

$Revision: 1003892 $ $Date: 2010-10-02 23:28:56 +0200 (sam. 02 oct. 2010) $

See Also:

WELL Random number generator, Serialized Form

Field Summary

Fields

Modifier and Type	Field	Description
protected int[]	i1	Index indirection table giving for each index the value index + m1 taking table size into account.
protected int[]	i2	Index indirection table giving for each index the value index + m2 taking table size into account.
protected int[]	i3	Index indirection table giving for each index the value index + m3 taking table size into account.
protected int	index	Current index in the bytes pool.
protected int[]	iRm1	Index indirection table giving for each index its predecessor taking table size into account.
protected int[]	iRm2	Index indirection table giving for each index its second predecessor taking table size into account.
protected int[]	v	Bytes pool.

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	AbstractWell(int k, int m1, int m2, int m3)	Creates a new random number generator.
protected	AbstractWell(int k, int m1, int m2, int m3, int seed)	Creates a new random number generator using a single int seed.
protected	AbstractWell(int k, int m1, int m2, int m3, int[] seed)	Creates a new random number generator using an int array seed.
protected	AbstractWell(int k, int m1, int m2, int m3, long seed)	Creates a new random number generator using a single long seed.

Method Summary

Modifier and Type	Method	Description
protected abstract int	next(int bits)	Generate next pseudorandom number.
void	setSeed(int seed)	Reinitialize the generator as if just built with the given int seed.
void	setSeed(int[] seed)	Reinitialize the generator as if just built with the given int array seed.
void	setSeed(long seed)	Reinitialize the generator as if just built with the given long seed.

Methods inherited from class org.apache.commons.math.random.BitsStreamGenerator

nextBoolean, nextBytes, nextDouble, nextFloat, nextGaussian, nextInt, nextInt, nextLong

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

index

protected int index

Current index in the bytes pool.

v

protected final int[] v

Bytes pool.

iRm1

protected final int[] iRm1

Index indirection table giving for each index its predecessor taking table size into account.

iRm2

protected final int[] iRm2

Index indirection table giving for each index its second predecessor taking table size into account.

i1

protected final int[] i1

Index indirection table giving for each index the value index + m1 taking table size into account.

i2

protected final int[] i2

Index indirection table giving for each index the value index + m2 taking table size into account.

i3

protected final int[] i3

Index indirection table giving for each index the value index + m3 taking table size into account.

Constructor Detail

AbstractWell

protected AbstractWell(int k,
                       int m1,
                       int m2,
                       int m3)

Creates a new random number generator.

The instance is initialized using the current time as the seed.

Parameters:

k - number of bits in the pool (not necessarily a multiple of 32)

m1 - first parameter of the algorithm

m2 - second parameter of the algorithm

m3 - third parameter of the algorithm

AbstractWell

protected AbstractWell(int k,
                       int m1,
                       int m2,
                       int m3,
                       int seed)

Creates a new random number generator using a single int seed.

Parameters:

k - number of bits in the pool (not necessarily a multiple of 32)

m1 - first parameter of the algorithm

m2 - second parameter of the algorithm

m3 - third parameter of the algorithm

seed - the initial seed (32 bits integer)

AbstractWell

protected AbstractWell(int k,
                       int m1,
                       int m2,
                       int m3,
                       int[] seed)

Creates a new random number generator using an int array seed.

Parameters:

k - number of bits in the pool (not necessarily a multiple of 32)

m1 - first parameter of the algorithm

m2 - second parameter of the algorithm

m3 - third parameter of the algorithm

seed - the initial seed (32 bits integers array), if null the seed of the generator will be related to the current time

AbstractWell

protected AbstractWell(int k,
                       int m1,
                       int m2,
                       int m3,
                       long seed)

Creates a new random number generator using a single long seed.

Parameters:

k - number of bits in the pool (not necessarily a multiple of 32)

m1 - first parameter of the algorithm

m2 - second parameter of the algorithm

m3 - third parameter of the algorithm

seed - the initial seed (64 bits integer)

Method Detail

setSeed

public void setSeed(int seed)

Reinitialize the generator as if just built with the given int seed.

The state of the generator is exactly the same as a new generator built with the same seed.

Specified by:

setSeed in interface RandomGenerator

Specified by:

setSeed in class BitsStreamGenerator

Parameters:

seed - the initial seed (32 bits integer)

setSeed

public void setSeed(int[] seed)

Reinitialize the generator as if just built with the given int array seed.

The state of the generator is exactly the same as a new generator built with the same seed.

Specified by:

setSeed in interface RandomGenerator

Specified by:

setSeed in class BitsStreamGenerator

Parameters:

seed - the initial seed (32 bits integers array), if null the seed of the generator will be related to the current time

setSeed

public void setSeed(long seed)

Reinitialize the generator as if just built with the given long seed.

The state of the generator is exactly the same as a new generator built with the same seed.

Specified by:

setSeed in interface RandomGenerator

Specified by:

setSeed in class BitsStreamGenerator

Parameters:

seed - the initial seed (64 bits integer)

next

protected abstract int next(int bits)

Generate next pseudorandom number.

This method is the core generation algorithm. It is used by all the public generation methods for the various primitive types BitsStreamGenerator.nextBoolean(), BitsStreamGenerator.nextBytes(byte[]), BitsStreamGenerator.nextDouble(), BitsStreamGenerator.nextFloat(), BitsStreamGenerator.nextGaussian(), BitsStreamGenerator.nextInt(), BitsStreamGenerator.next(int) and BitsStreamGenerator.nextLong().

Specified by:

next in class BitsStreamGenerator

Parameters:

bits - number of random bits to produce

Returns:

random bits generated