Class L64X1024Mix
- java.lang.Object
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- org.apache.commons.rng.core.BaseProvider
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- org.apache.commons.rng.core.source64.LongProvider
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- org.apache.commons.rng.core.source64.AbstractL64
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- org.apache.commons.rng.core.source64.L64X1024Mix
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- All Implemented Interfaces:
RandomLongSource
,JumpableUniformRandomProvider
,LongJumpableUniformRandomProvider
,RestorableUniformRandomProvider
,SplittableUniformRandomProvider
,UniformRandomProvider
public class L64X1024Mix extends AbstractL64 implements SplittableUniformRandomProvider
A 64-bit all purpose generator.This is a member of the LXM family of generators: L=Linear congruential generator; X=Xor based generator; and M=Mix. This member uses a 64-bit LCG and 1024-bit Xor-based generator. It is named as
"L64X1024MixRandom"
in thejava.util.random
package introduced in JDK 17; the LXM family is described in further detail in:Steele and Vigna (2021) LXM: better splittable pseudorandom number generators (and almost as fast). Proceedings of the ACM on Programming Languages, Volume 5, Article 148, pp 1–31.
Memory footprint is 1184 bits and the period is 264 (21024 - 1).
This generator implements
LongJumpableUniformRandomProvider
. In addition instances created with a different additive parameter for the LCG are robust against accidental correlation in a multi-threaded setting. The additive parameters must be different in the most significant 63-bits.This generator implements
SplittableUniformRandomProvider
. The stream of generators created using thesplits
methods support parallelisation and are robust against accidental correlation by using unique values for the additive parameter for each instance in the same stream. The primitive streaming methods support parallelisation but with no assurances of accidental correlation; each thread uses a new instance with a randomly initialised state.- Since:
- 1.5
- See Also:
- Steele & Vigna (2021) Proc. ACM Programming Languages 5, 1-31, JDK 17 java.util.random javadoc
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Field Summary
Fields Modifier and Type Field Description private int
index
Index in "state" array.private static int
LCG_STATE_SIZE
Size of the LCG state vector.private static long
M
LCG multiplier.private static int
SEED_SIZE
Size of the seed vector.private long[]
x
State of the XBG.private static int
XBG_STATE_SIZE
Size of the XBG state vector.-
Fields inherited from class org.apache.commons.rng.core.source64.AbstractL64
la, ls
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Constructor Summary
Constructors Modifier Constructor Description L64X1024Mix(long[] seed)
Creates a new instance.protected
L64X1024Mix(L64X1024Mix source)
Creates a copy instance.
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description (package private) AbstractL64
copy()
Create a copy.private static SplittableUniformRandomProvider
create(long seed, UniformRandomProvider source)
Create a new instance using the givenseed
andsource
of randomness to initialise the instance.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.long
next()
protected void
setStateInternal(byte[] s)
Resets the RNG to the givenstate
.SplittableUniformRandomProvider
split(UniformRandomProvider source)
Creates a new random generator, split off from this one, that implements theSplittableUniformRandomProvider
interface.java.util.stream.Stream<SplittableUniformRandomProvider>
splits(long streamSize, SplittableUniformRandomProvider source)
Returns a stream producing the givenstreamSize
number of new random generators, each of which implements theSplittableUniformRandomProvider
interface.-
Methods inherited from class org.apache.commons.rng.core.source64.LongProvider
nextBoolean, nextInt, nextLong, resetCachedState
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Methods inherited from class org.apache.commons.rng.core.BaseProvider
checkIndex, checkStateSize, composeStateInternal, extendSeed, extendSeed, fillState, fillState, restoreState, saveState, splitStateInternal, toString
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Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
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Methods inherited from interface org.apache.commons.rng.JumpableUniformRandomProvider
jumps, jumps
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Methods inherited from interface org.apache.commons.rng.LongJumpableUniformRandomProvider
longJumps, longJumps
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Methods inherited from interface org.apache.commons.rng.SplittableUniformRandomProvider
doubles, doubles, doubles, doubles, ints, ints, ints, ints, longs, longs, longs, longs, split, splits, splits, splits
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Methods inherited from interface org.apache.commons.rng.UniformRandomProvider
nextBoolean, nextBytes, nextBytes, nextDouble, nextDouble, nextDouble, nextFloat, nextFloat, nextFloat, nextInt, nextInt, nextInt, nextLong, nextLong, nextLong
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Field Detail
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SEED_SIZE
private static final int SEED_SIZE
Size of the seed vector.- See Also:
- Constant Field Values
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XBG_STATE_SIZE
private static final int XBG_STATE_SIZE
Size of the XBG state vector.- See Also:
- Constant Field Values
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LCG_STATE_SIZE
private static final int LCG_STATE_SIZE
Size of the LCG state vector.- See Also:
- Constant Field Values
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M
private static final long M
LCG multiplier.- See Also:
- Constant Field Values
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x
private final long[] x
State of the XBG.
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index
private int index
Index in "state" array.
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Constructor Detail
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L64X1024Mix
public L64X1024Mix(long[] seed)
Creates a new instance.- Parameters:
seed
- Initial seed. If the length is larger than 18, only the first 18 elements will be used; if smaller, the remaining elements will be automatically set. A seed containing all zeros in the last 16 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.
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L64X1024Mix
protected L64X1024Mix(L64X1024Mix source)
Creates a copy instance.- Parameters:
source
- Source to copy.
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Method Detail
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getStateInternal
protected byte[] getStateInternal()
Creates a snapshot of the RNG state.- Overrides:
getStateInternal
in classAbstractL64
- Returns:
- the internal state.
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setStateInternal
protected void setStateInternal(byte[] s)
Resets the RNG to the givenstate
.- Overrides:
setStateInternal
in classAbstractL64
- Parameters:
s
- State (previously obtained by a call toBaseProvider.getStateInternal()
).- See Also:
BaseProvider.checkStateSize(byte[],int)
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next
public long next()
- Specified by:
next
in interfaceRandomLongSource
- Returns:
- the next random value.
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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 (21024 - 1) positions. It can provide up to 264 non-overlapping subsequences.
- Specified by:
jump
in interfaceJumpableUniformRandomProvider
- Overrides:
jump
in classAbstractL64
- Returns:
- A copy of the current state.
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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 (21024 - 1) positions. It can provide up to 232 non-overlapping subsequences of length 232 (21024 - 1); each subsequence can provide up to 232 non-overlapping subsequences of length (21024 - 1) using the
jump()
method.- Specified by:
longJump
in interfaceLongJumpableUniformRandomProvider
- Overrides:
longJump
in classAbstractL64
- Returns:
- A copy of the current state.
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copy
AbstractL64 copy()
Create a copy.- Specified by:
copy
in classAbstractL64
- Returns:
- the copy
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split
public SplittableUniformRandomProvider split(UniformRandomProvider source)
Creates a new random generator, split off from this one, that implements theSplittableUniformRandomProvider
interface.- Specified by:
split
in interfaceSplittableUniformRandomProvider
- Parameters:
source
- A source of randomness used to initialise the new instance.- Returns:
- A new instance.
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splits
public java.util.stream.Stream<SplittableUniformRandomProvider> splits(long streamSize, SplittableUniformRandomProvider source)
Returns a stream producing the givenstreamSize
number of new random generators, each of which implements theSplittableUniformRandomProvider
interface.- Specified by:
splits
in interfaceSplittableUniformRandomProvider
- Parameters:
streamSize
- Number of objects to generate.source
- A source of randomness used to initialise the new instances; this may be split to provide a source of randomness across a parallel stream.- Returns:
- a stream of random generators; the stream is limited to the given
streamSize
.
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create
private static SplittableUniformRandomProvider create(long seed, UniformRandomProvider source)
Create a new instance using the givenseed
andsource
of randomness to initialise the instance.- Parameters:
seed
- Seed used to initialise the instance.source
- Source of randomness used to initialise the instance.- Returns:
- A new instance.
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