Class XorShift1024Star

java.lang.Object

org.apache.commons.rng.core.BaseProvider

org.apache.commons.rng.core.source64.LongProvider

org.apache.commons.rng.core.source64.XorShift1024Star

All Implemented Interfaces:

RandomLongSource, JumpableUniformRandomProvider, RestorableUniformRandomProvider, UniformRandomProvider

Direct Known Subclasses:

XorShift1024StarPhi

public class XorShift1024Star
extends LongProvider
implements JumpableUniformRandomProvider

A fast RNG implementing the XorShift1024* algorithm.

Note: This has been superseded by XorShift1024StarPhi. The sequences emitted by both generators are correlated.

Since:

1.0

See Also:

• Original source code
• Xorshift (Wikipedia)

Field Summary

Fields

Modifier and Type	Field	Description
private int	index	Index in "state" array.
private static final long[]	JUMP_COEFFICIENTS	The coefficients for the jump function.
private final long	multiplier	The multiplier for the XorShift1024 algorithm.
private static final int	SEED_SIZE	Size of the state vector.
private final long[]	state	State.

Constructor Summary

Constructors

Modifier	Constructor	Description
	XorShift1024Star(long[] seed)	Creates a new instance.
protected	XorShift1024Star(long[] seed, long multiplier)	Creates a new instance.
protected	XorShift1024Star(XorShift1024Star source)	Creates a copy instance.

Method Summary

Modifier and Type	Method	Description
protected XorShift1024Star	copy()	Create a copy.
protected byte[]	getStateInternal()	Creates a snapshot of the RNG state.
UniformRandomProvider	jump()	Creates a copy of the UniformRandomProvider and then advances the state of the current instance.
long	next()	Return the next random value.
private void	performJump()	Perform the jump to advance the generator state.
private void	setSeedInternal(long[] seed)	Seeds the RNG.
protected void	setStateInternal(byte[] s)	Resets the RNG to the given state.

Methods inherited from class LongProvider

nextBoolean, nextInt, nextLong, resetCachedState

Methods inherited from class BaseProvider

checkIndex, checkStateSize, composeStateInternal, extendSeed, extendSeed, fillState, fillState, restoreState, saveState, splitStateInternal, toString

Methods inherited from class Object

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

Methods inherited from interface JumpableUniformRandomProvider

jumps, jumps

Methods inherited from interface UniformRandomProvider

doubles, doubles, doubles, doubles, ints, ints, ints, ints, longs, longs, longs, longs, nextBoolean, nextBytes, nextBytes, nextDouble, nextDouble, nextDouble, nextFloat, nextFloat, nextFloat, nextInt, nextInt, nextInt, nextLong, nextLong, nextLong

Field Details

SEED_SIZE

private static final int SEED_SIZE

Size of the state vector.

See Also:

• Constant Field Values

JUMP_COEFFICIENTS

private static final long[] JUMP_COEFFICIENTS

The coefficients for the jump function.

state

private final long[] state

State.

multiplier

private final long multiplier

The multiplier for the XorShift1024 algorithm.

index

private int index

Index in "state" array.

Constructor Details

XorShift1024Star

public XorShift1024Star(long[] seed)

Creates a new instance.

Parameters:

seed - Initial seed. If the length is larger than 16, only the first 16 elements will be used; if smaller, the remaining elements will be automatically set. A seed containing all zeros will create a non-functional generator.

XorShift1024Star

protected XorShift1024Star(long[] seed,
 long multiplier)

Creates a new instance.

Parameters:

seed - Initial seed. If the length is larger than 16, only the first 16 elements will be used; if smaller, the remaining elements will be automatically set. A seed containing all zeros will create a non-functional generator.

multiplier - The multiplier for the XorShift1024 algorithm.

Since:

1.3

XorShift1024Star

protected XorShift1024Star(XorShift1024Star source)

Creates a copy instance.

Parameters:

source - Source to copy.

Since:

1.3

Method Details

getStateInternal

protected byte[] getStateInternal()

Creates a snapshot of the RNG state.

Overrides:

getStateInternal in class LongProvider

Returns:

the internal state.

setStateInternal

protected void setStateInternal(byte[] s)

Resets the RNG to the given state.

Overrides:

setStateInternal in class LongProvider

Parameters:

s - State (previously obtained by a call to BaseProvider.getStateInternal()).

See Also:

• BaseProvider.checkStateSize(byte[],int)

setSeedInternal

private void setSeedInternal(long[] seed)

Seeds the RNG.

Parameters:

seed - Seed.

next

public long next()

Return the next random value.

Specified by:

next in interface RandomLongSource

Returns:

the next random value.

jump

public UniformRandomProvider jump()

Creates a copy of the UniformRandomProvider and then advances the state of the current instance. The copy is returned.

The current state will be advanced in a single operation by the equivalent of a number of sequential calls to a method that updates the state of the provider. The size of the jump is implementation dependent.

Repeat invocations of this method will create a series of generators that are uniformly spaced at intervals of the output sequence. Each generator provides non-overlapping output for the length of the jump for use in parallel computations.

The jump size is the equivalent of 2⁵¹² calls to nextLong(). It can provide up to 2⁵¹² non-overlapping subsequences.

Specified by:

jump in interface JumpableUniformRandomProvider

Returns:

A copy of the current state.

Since:

1.3

copy

protected XorShift1024Star copy()

Create a copy.

Returns:

the copy

Since:

1.3

performJump

private void performJump()

Perform the jump to advance the generator state. Resets the cached state of the generator.