Class XoShiRo256Plus

java.lang.Object

org.apache.commons.rng.core.BaseProvider

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

org.apache.commons.rng.core.source64.XoShiRo256Plus

All Implemented Interfaces:

RandomLongSource, JumpableUniformRandomProvider, LongJumpableUniformRandomProvider, RestorableUniformRandomProvider, UniformRandomProvider

public class XoShiRo256Plus
extends LongProvider

A fast 64-bit generator suitable for double generation. This is slightly faster than the all-purpose generator XoShiRo256StarStar.

This is a member of the Xor-Shift-Rotate family of generators. Memory footprint is 256 bits and the period is 2²⁵⁶-1.

Since:

1.3

See Also:

• Original source code
• xorshiro / xoroshiro generators

Field Summary

Fields

Modifier and Type	Field	Description
protected long	state0	State 0 of the generator.
protected long	state1	State 1 of the generator.
protected long	state2	State 2 of the generator.
protected long	state3	State 3 of the generator.

Constructor Summary

Constructors

Modifier	Constructor	Description
	XoShiRo256Plus(long[] seed)	Creates a new instance.
	XoShiRo256Plus(long seed0, long seed1, long seed2, long seed3)	Creates a new instance using a 4 element seed.
protected	XoShiRo256Plus(XoShiRo256Plus source)	Creates a copy instance.

Method Summary

Modifier and Type	Method	Description
protected XoShiRo256Plus	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.
JumpableUniformRandomProvider	longJump()	Creates a copy of the JumpableUniformRandomProvider and then advances the state of the current instance.
long	next()	Return the next random value.
protected long	nextOutput()	Use the current state to compute the next output from the generator.
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 LongJumpableUniformRandomProvider

longJumps, longJumps

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

state0

protected long state0

State 0 of the generator.

state1

protected long state1

State 1 of the generator.

state2

protected long state2

State 2 of the generator.

state3

protected long state3

State 3 of the generator.

Constructor Details

XoShiRo256Plus

public XoShiRo256Plus(long[] seed)

Creates a new instance.

Parameters:

seed - Initial seed. If the length is larger than 4, only the first 4 elements will be used; if smaller, the remaining elements will be automatically set. A seed containing all zeros will create a non-functional generator.

XoShiRo256Plus

public XoShiRo256Plus(long seed0,
 long seed1,
 long seed2,
 long seed3)

Creates a new instance using a 4 element seed. A seed containing all zeros will create a non-functional generator.

Parameters:

seed0 - Initial seed element 0.

seed1 - Initial seed element 1.

seed2 - Initial seed element 2.

seed3 - Initial seed element 3.

XoShiRo256Plus

protected XoShiRo256Plus(XoShiRo256Plus source)

Creates a copy instance.

Parameters:

source - Source to copy.

Method Details

nextOutput

protected long nextOutput()

Use the current state to compute the next output from the generator. The output function shall vary with respect to different generators. This method is called from RandomLongSource.next() before the current state is updated.

Returns:

the next output

copy

protected XoShiRo256Plus copy()

Create a copy.

Returns:

the copy

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)

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 2¹²⁸ calls to nextLong(). It can provide up to 2¹²⁸ non-overlapping subsequences.

Specified by:

jump in interface JumpableUniformRandomProvider

Returns:

A copy of the current state.

longJump

public JumpableUniformRandomProvider longJump()

Creates a copy of the JumpableUniformRandomProvider 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 long 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 long jump for use in parallel computations.

The returned copy may be jumped m / n times before overlap with the current instance where m is the long jump length and n is the jump length of the JumpableUniformRandomProvider.jump() method.

The jump size is the equivalent of 2¹⁹² calls to nextLong(). It can provide up to 2⁶⁴ non-overlapping subsequences of length 2¹⁹²; each subsequence can provide up to 2⁶⁴ non-overlapping subsequences of length 2¹²⁸ using the JumpableUniformRandomProvider.jump() method.

Specified by:

longJump in interface LongJumpableUniformRandomProvider

Returns:

A copy of the current state.