Class AbstractL64X128

java.lang.Object

org.apache.commons.rng.core.BaseProvider

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

org.apache.commons.rng.core.source64.AbstractL64

org.apache.commons.rng.core.source64.AbstractL64X128

All Implemented Interfaces:

RandomLongSource, JumpableUniformRandomProvider, LongJumpableUniformRandomProvider, RestorableUniformRandomProvider, UniformRandomProvider

Direct Known Subclasses:

L64X128Mix, L64X128StarStar

abstract class AbstractL64X128
extends AbstractL64

This abstract class is a base for algorithms from the LXM family of generators with a 64-bit LCG and 128-bit XBG sub-generator. The class implements the state save/restore functions.

Since:

1.5

Field Summary

Fields

Modifier and Type	Field	Description
protected static final long	M	LCG multiplier.
private static final int	SEED_SIZE	Size of the seed vector.
protected long	x0	State 0 of the XBG.
protected long	x1	State 1 of the XBG.
private static final int	XBG_STATE_SIZE	Size of the XBG state vector.

Fields inherited from class AbstractL64

la, ls

Constructor Summary

Constructors

Constructor	Description
AbstractL64X128(long[] seed)	Creates a new instance.
AbstractL64X128(long seed0, long seed1, long seed2, long seed3)	Creates a new instance using a 4 element seed.
AbstractL64X128(AbstractL64X128 source)	Creates a copy instance.

Method Summary

Modifier and Type	Method	Description
protected byte[]	getStateInternal()	Creates a snapshot of the RNG state.
UniformRandomProvider	jump()	Creates a copy of the UniformRandomProvider and then retreats the state of the current instance.
JumpableUniformRandomProvider	longJump()	Creates a copy of the UniformRandomProvider and then retreats the state of the current instance.
protected void	setStateInternal(byte[] s)	Resets the RNG to the given state.

Methods inherited from class AbstractL64

copy

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 RandomLongSource

next

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

M

protected static final long M

LCG multiplier.

See Also:

• Constant Field Values

SEED_SIZE

private static final int SEED_SIZE

Size of the seed vector.

See Also:

• Constant Field Values

XBG_STATE_SIZE

private static final int XBG_STATE_SIZE

Size of the XBG state vector.

See Also:

• Constant Field Values

x0

protected long x0

State 0 of the XBG.

x1

protected long x1

State 1 of the XBG.

Constructor Details

AbstractL64X128

AbstractL64X128(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 in the last two elements will create a non-functional XBG sub-generator and a low quality output with a period of 2⁶⁴.

The 1st element is used to set the LCG increment; the least significant bit is set to odd to ensure a full period LCG. The 2nd element is used to set the LCG state.

AbstractL64X128

AbstractL64X128(long seed0,
 long seed1,
 long seed2,
 long seed3)

Creates a new instance using a 4 element seed. A seed containing all zeros in the last two elements will create a non-functional XBG sub-generator and a low quality output with a period of 2⁶⁴.

The 1st element is used to set the LCG increment; the least significant bit is set to odd to ensure a full period LCG. The 2nd element is used to set the LCG state.

Parameters:

seed0 - Initial seed element 0.

seed1 - Initial seed element 1.

seed2 - Initial seed element 2.

seed3 - Initial seed element 3.

AbstractL64X128

AbstractL64X128(AbstractL64X128 source)

Creates a copy instance.

Parameters:

source - Source to copy.

Method Details

getStateInternal

protected byte[] getStateInternal()

Creates a snapshot of the RNG state.

Overrides:

getStateInternal in class AbstractL64

Returns:

the internal state.

setStateInternal

protected void setStateInternal(byte[] s)

Resets the RNG to the given state.

Overrides:

setStateInternal in class AbstractL64

Parameters:

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

See Also:

• BaseProvider.checkStateSize(byte[],int)

jump

public UniformRandomProvider jump()

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

The jump is performed by advancing the state of the LCG sub-generator by 1 cycle. The XBG state is unchanged.

The jump size is the equivalent of moving the state backwards by (2¹²⁸ - 1) positions. It can provide up to 2⁶⁴ non-overlapping subsequences.

Specified by:

jump in interface JumpableUniformRandomProvider

Overrides:

jump in class AbstractL64

Returns:

A copy of the current state.

longJump

public JumpableUniformRandomProvider longJump()

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

The jump is performed by advancing the state of the LCG sub-generator by 2³² cycles. The XBG state is unchanged.

The jump size is the equivalent of moving the state backwards by 2³² (2¹²⁸ - 1) positions. It can provide up to 2³² non-overlapping subsequences of length 2³² (2¹²⁸ - 1); each subsequence can provide up to 2³² non-overlapping subsequences of length (2¹²⁸ - 1) using the jump() method.

Specified by:

longJump in interface LongJumpableUniformRandomProvider

Overrides:

longJump in class AbstractL64

Returns:

A copy of the current state.