Package org.hipparchus.random

Class AbstractWell

java.lang.Object

org.hipparchus.random.AbstractWell

All Implemented Interfaces:

Serializable, RandomGenerator

Direct Known Subclasses:

Well1024a, Well19937a, Well19937c, Well44497a, Well44497b, Well512a

public abstract class AbstractWell
extends Object
implements 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.

See Also:

WELL Random number generator, Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
protected static class	AbstractWell.IndexTable	Inner class used to store the indirection index table which is fixed for a given type of WELL class of pseudo-random number generator.

Field Summary

Fields

Modifier and Type	Field	Description
protected int	index	Current index in the bytes pool.
protected int[]	v	Bytes pool.

Constructor Summary

Constructors

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

Method Summary

Modifier and Type	Method	Description
protected void	clearCache()	Clears the cache used by the default implementation of RandomGenerator.nextGaussian().
boolean	nextBoolean()	Returns the next pseudorandom, uniformly distributed boolean value from this random number generator's sequence.
void	nextBytes(byte[] bytes)	Generates random bytes and places them into a user-supplied byte array.
void	nextBytes(byte[] bytes, int start, int len)	Generates random bytes and places them into a user-supplied byte array.
double	nextDouble()	Returns the next pseudorandom, uniformly distributed double value between 0.0 and 1.0 from this random number generator's sequence.
float	nextFloat()	Returns the next pseudorandom, uniformly distributed float value between 0.0 and 1.0 from this random number generator's sequence.
double	nextGaussian()	Returns the next pseudorandom, Gaussian ("normally") distributed double value with mean 0.0 and standard deviation 1.0 from this random number generator's sequence.
abstract int	nextInt()	Returns the next pseudorandom, uniformly distributed int value from this random number generator's sequence.
int	nextInt(int n)	Returns a pseudorandom, uniformly distributed int value between 0 (inclusive) and the specified value (exclusive), drawn from this random number generator's sequence.
long	nextLong()	Returns the next pseudorandom, uniformly distributed long value from this random number generator's sequence.
long	nextLong(long n)	Returns a pseudorandom, uniformly distributed int value between 0 (inclusive) and the specified value (exclusive), drawn from this random number generator's sequence.
void	setSeed(int seed)	Sets the seed of the underlying random number generator using an int seed.
void	setSeed(int[] seed)	Reinitialize the generator as if just built with the given int array seed.
void	setSeed(long seed)	Sets the seed of the underlying random number generator using a long seed.
String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

index

protected int index

Current index in the bytes pool.

v

protected final int[] v

Bytes pool.

Constructor Detail

AbstractWell

protected AbstractWell(int k)

Creates a new random number generator.

The instance is initialized using the current time plus the system identity hash code of this instance as the seed.

Parameters:

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

AbstractWell

protected AbstractWell(int k,
                       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)

seed - the initial seed (32 bits integer)

AbstractWell

protected AbstractWell(int k,
                       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)

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,
                       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)

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 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

Parameters:

seed - the initial seed (32 bits integers array). If null the seed of the generator will be the system time plus the system identity hash code of the instance.

nextInt

public abstract int nextInt()

Returns the next pseudorandom, uniformly distributed int value from this random number generator's sequence.

All 2³² possible int values should be produced with (approximately) equal probability.

Returns:

the next pseudorandom, uniformly distributed int value from this random number generator's sequence

nextBoolean

public boolean nextBoolean()

Returns the next pseudorandom, uniformly distributed boolean value from this random number generator's sequence.

Returns:

the next pseudorandom, uniformly distributed boolean value from this random number generator's sequence

nextDouble

public double nextDouble()

Returns the next pseudorandom, uniformly distributed double value between 0.0 and 1.0 from this random number generator's sequence.

Returns:

the next pseudorandom, uniformly distributed double value between 0.0 and 1.0 from this random number generator's sequence

nextFloat

public float nextFloat()

Returns the next pseudorandom, uniformly distributed float value between 0.0 and 1.0 from this random number generator's sequence.

Returns:

the next pseudorandom, uniformly distributed float value between 0.0 and 1.0 from this random number generator's sequence

nextLong

public long nextLong()

Returns the next pseudorandom, uniformly distributed long value from this random number generator's sequence. All 2⁶⁴ possible long values should be produced with (approximately) equal probability.

Returns:

the next pseudorandom, uniformly distributed long value from this random number generator's sequence

nextBytes

public void nextBytes(byte[] bytes)

Generates random bytes and places them into a user-supplied byte array. The number of random bytes produced is equal to the length of the byte array.

Parameters:

bytes - the non-null byte array in which to put the random bytes

nextBytes

public void nextBytes(byte[] bytes,
                      int start,
                      int len)

Generates random bytes and places them into a user-supplied byte array.

Parameters:

bytes - the non-null byte array in which to put the random bytes

start - the starting index for inserting the generated bytes into the array

len - the number of bytes to generate

setSeed

public void setSeed(int seed)

Sets the seed of the underlying random number generator using an int seed.

Sequences of values generated starting with the same seeds should be identical.

Specified by:

setSeed in interface RandomGenerator

Parameters:

seed - the seed value

setSeed

public void setSeed(long seed)

Sets the seed of the underlying random number generator using a long seed.

Sequences of values generated starting with the same seeds should be identical.

Specified by:

setSeed in interface RandomGenerator

Parameters:

seed - the seed value

nextInt

public int nextInt(int n)
            throws IllegalArgumentException

Returns a pseudorandom, uniformly distributed int value between 0 (inclusive) and the specified value (exclusive), drawn from this random number generator's sequence.

Specified by:

nextInt in interface RandomGenerator

Parameters:

n - the bound on the random number to be returned. Must be positive.

Returns:

a pseudorandom, uniformly distributed int value between 0 (inclusive) and n (exclusive).

Throws:

IllegalArgumentException - if n is not positive.

nextLong

public long nextLong(long n)

Returns a pseudorandom, uniformly distributed int value between 0 (inclusive) and the specified value (exclusive), drawn from this random number generator's sequence.

Specified by:

nextLong in interface RandomGenerator

Parameters:

n - the bound on the random number to be returned. Must be positive.

Returns:

a pseudorandom, uniformly distributed int value between 0 (inclusive) and n (exclusive).

nextGaussian

public double nextGaussian()

Returns the next pseudorandom, Gaussian ("normally") distributed double value with mean 0.0 and standard deviation 1.0 from this random number generator's sequence.

Specified by:

nextGaussian in interface RandomGenerator

Returns:

the next pseudorandom, Gaussian ("normally") distributed double value with mean 0.0 and standard deviation 1.0 from this random number generator's sequence

clearCache

protected void clearCache()

Clears the cache used by the default implementation of RandomGenerator.nextGaussian().

toString

public String toString()

Overrides:

toString in class Object