Package org.apache.commons.rng.core.source32

Class Philox4x32

java.lang.Object

org.apache.commons.rng.core.BaseProvider

org.apache.commons.rng.core.source32.IntProvider

org.apache.commons.rng.core.source32.Philox4x32

All Implemented Interfaces:

ArbitrarilyJumpableUniformRandomProvider, RandomIntSource, JumpableUniformRandomProvider, LongJumpableUniformRandomProvider, RestorableUniformRandomProvider, UniformRandomProvider

public final class Philox4x32
extends IntProvider
implements LongJumpableUniformRandomProvider, ArbitrarilyJumpableUniformRandomProvider

This class implements the Philox4x32 128-bit counter-based generator with 10 rounds.

This is a member of the Philox family of generators. Memory footprint is 192 bits and the period is 2¹³⁰.

Jumping in the sequence is essentially instantaneous. This generator provides both subsequences and arbitrary jumps for easy parallelization.

References:

1. Salmon, J.K. et al (2011) Parallel Random Numbers: As Easy as 1,2,3.

Since:

1.7

Constructor Summary

Constructors

Constructor	Description
Philox4x32(int[] seed)	Creates a new instance based on an array of int containing, key (first two ints) and the counter (next 4 ints, low bits = first int).

Method Summary

Modifier and Type	Method	Description
protected byte[]	getStateInternal()	Creates a snapshot of the RNG state.
UniformRandomProvider	jump()
ArbitrarilyJumpableUniformRandomProvider	jump(double distance)
ArbitrarilyJumpableUniformRandomProvider	jumpPowerOfTwo(int logDistance)
Stream<ArbitrarilyJumpableUniformRandomProvider>	jumps(double distance)
JumpableUniformRandomProvider	longJump()
int	next()	Return the next random value.
protected void	setStateInternal(byte[] s)	Resets the RNG to the given state.

Methods inherited from class org.apache.commons.rng.core.source32.IntProvider

nextBoolean, nextBytes, nextBytes, nextDouble, nextInt, nextLong, resetCachedState

Methods inherited from class org.apache.commons.rng.core.BaseProvider

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

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.commons.rng.ArbitrarilyJumpableUniformRandomProvider

jumps

Methods inherited from interface org.apache.commons.rng.JumpableUniformRandomProvider

jumps, jumps

Methods inherited from interface org.apache.commons.rng.LongJumpableUniformRandomProvider

longJumps, longJumps

Methods inherited from interface org.apache.commons.rng.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

Constructor Detail

Philox4x32

public Philox4x32(int[] seed)

Creates a new instance based on an array of int containing, key (first two ints) and the counter (next 4 ints, low bits = first int). The counter is not scrambled and may be used to create contiguous blocks with size a multiple of 4 ints. For example, setting seed[2] = 1 is equivalent to start with seed[2]=0 and calling next() 4 times.

Parameters:

seed - Array of size 6 defining key0,key1,counter0,counter1,counter2,counter3. If the size is smaller, zero values are assumed.

Method Detail

getStateInternal

protected byte[] getStateInternal()

Creates a snapshot of the RNG state.

Overrides:

getStateInternal in class IntProvider

Returns:

the internal state.

setStateInternal

protected void setStateInternal(byte[] s)

Resets the RNG to the given state.

Overrides:

setStateInternal in class IntProvider

Parameters:

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

See Also:

BaseProvider.checkStateSize(byte[],int)

next

public int next()

Return the next random value.

Specified by:

next in interface RandomIntSource

Returns:

the next random value.

jump

public UniformRandomProvider jump()

The jump size is the equivalent of 2⁶⁶ calls to nextInt(). It can provide up to 2⁶⁴ non-overlapping subsequences.

Specified by:

jump in interface JumpableUniformRandomProvider

longJump

public JumpableUniformRandomProvider longJump()

The jump size is the equivalent of 2⁹⁸ calls to nextLong(). It can provide up to 2³² non-overlapping subsequences of length 2⁹⁸; each subsequence can provide up to 2³² non-overlapping subsequences of length 2⁶⁶ using the jump() method.

Specified by:

longJump in interface LongJumpableUniformRandomProvider

jump

public ArbitrarilyJumpableUniformRandomProvider jump(double distance)

Specified by:

jump in interface ArbitrarilyJumpableUniformRandomProvider

jumpPowerOfTwo

public ArbitrarilyJumpableUniformRandomProvider jumpPowerOfTwo(int logDistance)

Specified by:

jumpPowerOfTwo in interface ArbitrarilyJumpableUniformRandomProvider

jumps

public Stream<ArbitrarilyJumpableUniformRandomProvider> jumps(double distance)

Specified by:

jumps in interface ArbitrarilyJumpableUniformRandomProvider