org.hipparchus.random

Class Well19937a

java.lang.Object

org.hipparchus.random.AbstractWell

org.hipparchus.random.Well19937a

All Implemented Interfaces:

Serializable, RandomGenerator

public class Well19937a
extends AbstractWell

This class implements the WELL19937a 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/interfaces inherited from class org.hipparchus.random.AbstractWell

AbstractWell.IndexTable

Field Summary

Fields inherited from class org.hipparchus.random.AbstractWell

index, v

Constructor Summary

Constructors

Constructor and Description
Well19937a() Creates a new random number generator.
Well19937a(int seed) Creates a new random number generator using a single int seed.
Well19937a(int[] seed) Creates a new random number generator using an int array seed.
Well19937a(long seed) Creates a new random number generator using a single long seed.

Method Summary

Modifier and Type	Method and Description
protected void	clearCache() Clears the cache used by the default implementation of 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.
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(long seed) Sets the seed of the underlying random number generator using a long seed.
String	toString()

Methods inherited from class org.hipparchus.random.AbstractWell

setSeed

Methods inherited from class java.lang.Object

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

Constructor Detail

Well19937a

public Well19937a()

Creates a new random number generator.

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

Well19937a

public Well19937a(int seed)

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

Parameters:

seed - the initial seed (32 bits integer)

Well19937a

public Well19937a(int[] seed)

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

Parameters:

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

Well19937a

public Well19937a(long seed)

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

Parameters:

seed - the initial seed (64 bits integer)

Method Detail

nextInt

public 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.

Specified by:

nextInt in interface RandomGenerator

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 nextGaussian.

toString

public String toString()

Overrides:

toString in class Object