Package com.github.tommyettinger.random

Class Crand64Random

java.lang.Object

java.util.Random

com.github.tommyettinger.random.EnhancedRandom

com.github.tommyettinger.random.Crand64Random

All Implemented Interfaces:

Externalizable, Serializable, RandomGenerator

public class Crand64Random
extends EnhancedRandom

A 256-bit "chaotic" generator that also includes an (odd-number) 64-bit stream. This generator was inspired by SFC64, but has diverged significantly. Like SFC64, it uses a counter (Weyl sequence), so it has a minimum cycle length of 2 to the 64. The maximum cycle length for any given state is unknown exactly, but must be less than 2 to the 256. There are 2 to the 63 possible streams, all distinct, though the presence of flawed streams can't really be ruled out (they should be extremely unlikely; even the stream 1L is good).
From the original source:
Very fast PRNG suited for parallel usage with Weyl-sequence parameter. 320-bit state, 256 bit is mutable. Noticable faster than xoshiro and pcg, slighly slower than wyrand64 and Romu, but these have restricted capacity for larger parallel jobs or unknown minimum periods. crand_t supports 2^63 unique threads with a minimum 2^64 period lengths each. Passes all statistical tests, e.g PractRand and correlation tests, i.e. interleaved streams with one-bit diff state. Even the 16-bit version (LR=6, RS=5, LS=3) passes PractRand to multiple TB input.
[sic]
Note that most other generators in Juniper have been tested more thoroughly, but 8TB of PractRand is still excellent.
This implements all optional methods in EnhancedRandom except EnhancedRandom.skip(long) and EnhancedRandom.previousLong().
Based on STC's crand.h. The original code is MIT-licensed, and was originally written by Tyge Løvset.

See Also:

• Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from interface java.util.random.RandomGenerator

RandomGenerator.ArbitrarilyJumpableGenerator, RandomGenerator.JumpableGenerator, RandomGenerator.LeapableGenerator, RandomGenerator.SplittableGenerator, RandomGenerator.StreamableGenerator

Field Summary

Fields

Modifier and Type	Field	Description
protected long	stateA	The first state; can be any long.
protected long	stateB	The second state; can be any long.
protected long	stateC	The third state; can be any long.
protected long	stateD	The fourth state; can be any long.
protected long	stateE	The fifth state; must be an odd number, but otherwise can be any long.

Constructor Summary

Constructors

Constructor	Description
Crand64Random()	Creates a new AceRandom with a random state.
Crand64Random(long seed)	Creates a new AceRandom with the given seed; all long values are permitted.
Crand64Random(long stateA, long stateB, long stateC, long stateD, long stateE)	Creates a new AceRandom with the given five states; all long values are permitted.

Method Summary

Modifier and Type	Method	Description
Crand64Random	copy()	Creates a new EnhancedRandom with identical states to this one, so if the same EnhancedRandom methods are called on this object and its copy (in the same order), the same outputs will be produced.
boolean	equals(Object o)
long	getSelectedState(int selection)	Gets the state determined by selection, as-is.
long	getStateA()
long	getStateB()
long	getStateC()
int	getStateCount()	This generator has 5 long states, so this returns 5.
long	getStateD()
long	getStateE()
String	getTag()	Gets the tag used to identify this type of EnhancedRandom, as a String.
int	next(int bits)	Generates the next pseudorandom number with a specific maximum size in bits (not a max number).
long	nextLong()	Returns the next pseudorandom, uniformly distributed long value from this random number generator's sequence.
void	setSeed(long seed)	This initializes all 5 states of the generator to random values based on the given seed.
void	setSelectedState(int selection, long value)	Sets one of the states, determined by selection, to value, as-is.
void	setState(long stateA, long stateB, long stateC, long stateD, long stateE)	Sets the state completely to the given five state variables.
void	setStateA(long stateA)	Sets the first part of the state.
void	setStateB(long stateB)	Sets the second part of the state.
void	setStateC(long stateC)	Sets the third part of the state.
void	setStateD(long stateD)	Sets the fourth part of the state.
void	setStateE(long stateE)	Sets the fifth part of the state.
String	toString()

Methods inherited from class com.github.tommyettinger.random.EnhancedRandom

areEqual, fixGamma, maxDoubleOf, maxFloatOf, maxIntOf, maxLongOf, minDoubleOf, minFloatOf, minIntOf, minLongOf, nextBoolean, nextBoolean, nextBytes, nextDouble, nextDouble, nextDouble, nextExclusiveDouble, nextExclusiveDouble, nextExclusiveDouble, nextExclusiveDoubleEquidistant, nextExclusiveFloat, nextExclusiveFloat, nextExclusiveFloat, nextExclusiveFloatEquidistant, nextExclusiveSignedDouble, nextExclusiveSignedFloat, nextFloat, nextFloat, nextFloat, nextGaussian, nextGaussian, nextInclusiveDouble, nextInclusiveDouble, nextInclusiveDouble, nextInclusiveFloat, nextInclusiveFloat, nextInclusiveFloat, nextInt, nextInt, nextInt, nextLong, nextLong, nextSign, nextSignedInt, nextSignedInt, nextSignedLong, nextSignedLong, nextTriangular, nextTriangular, nextTriangular, nextTriangular, nextUnsignedInt, previousInt, previousLong, probit, randomElement, randomElement, readExternal, seedFromMath, setState, setState, setState, setState, setState, setWith, shuffle, shuffle, shuffle, shuffle, shuffle, shuffle, shuffle, shuffle, shuffle, shuffle, shuffle, shuffle, shuffle, shuffle, shuffle, shuffle, shuffle, shuffle, shuffle, shuffle, skip, stringDeserialize, stringDeserialize, stringSerialize, stringSerialize, writeExternal

Methods inherited from class java.util.Random

doubles, doubles, doubles, doubles, ints, ints, ints, ints, longs, longs, longs, longs

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.random.RandomGenerator

isDeprecated, nextExponential

Field Details

stateA

protected long stateA

The first state; can be any long.

stateB

protected long stateB

The second state; can be any long.

stateC

protected long stateC

The third state; can be any long.

stateD

protected long stateD

The fourth state; can be any long.

stateE

protected long stateE

The fifth state; must be an odd number, but otherwise can be any long.

Constructor Details

Crand64Random

public Crand64Random()

Creates a new AceRandom with a random state.

Crand64Random

public Crand64Random(long seed)

Creates a new AceRandom with the given seed; all long values are permitted. The seed will be passed to setSeed(long) to attempt to adequately distribute the seed randomly.

Parameters:

seed - any long value

Crand64Random

public Crand64Random(long stateA,
 long stateB,
 long stateC,
 long stateD,
 long stateE)

Creates a new AceRandom with the given five states; all long values are permitted. These states will be used verbatim.

Parameters:

stateA - any long value

stateB - any long value

stateC - any long value

stateD - any long value

stateE - any long value

Method Details

getTag

public String getTag()

Description copied from class: EnhancedRandom

Gets the tag used to identify this type of EnhancedRandom, as a String. This tag should be unique, and for uniformity purposes, all tags used in this library are 4 characters long. User-defined tags should have a different length.

Specified by:

getTag in class EnhancedRandom

Returns:

a unique String identifier for this type of EnhancedRandom; usually 4 chars long.

getStateCount

public int getStateCount()

This generator has 5 long states, so this returns 5.

Overrides:

getStateCount in class EnhancedRandom

Returns:

5 (five)

getSelectedState

public long getSelectedState(int selection)

Gets the state determined by selection, as-is. The value for selection should be between 0 and 4, inclusive; if it is any other value this gets state E as if 4 was given.

Overrides:

getSelectedState in class EnhancedRandom

Parameters:

selection - used to select which state variable to get; generally 0, 1, 2, 3, or 4

Returns:

the value of the selected state

setSelectedState

public void setSelectedState(int selection,
 long value)

Sets one of the states, determined by selection, to value, as-is. Selections 0, 1, 2, 3, and 4 refer to states A, B, C, D, and E, and if the selection is anything else, this treats it as 4 and sets stateE.

Overrides:

setSelectedState in class EnhancedRandom

Parameters:

selection - used to select which state variable to set; generally 0, 1, 2, 3, or 4

value - the exact value to use for the selected state, if valid

setSeed

public void setSeed(long seed)

This initializes all 5 states of the generator to random values based on the given seed. (2 to the 64) possible initial generator states can be produced here, all with a different first value returned by nextLong().

Specified by:

setSeed in class EnhancedRandom

Parameters:

seed - the initial seed; may be any long

getStateA

public long getStateA()

setStateA

public void setStateA(long stateA)

Sets the first part of the state.

Parameters:

stateA - can be any long

getStateB

public long getStateB()

setStateB

public void setStateB(long stateB)

Sets the second part of the state.

Parameters:

stateB - can be any long

getStateC

public long getStateC()

setStateC

public void setStateC(long stateC)

Sets the third part of the state.

Parameters:

stateC - can be any long

getStateD

public long getStateD()

setStateD

public void setStateD(long stateD)

Sets the fourth part of the state.

Parameters:

stateD - can be any long

getStateE

public long getStateE()

setStateE

public void setStateE(long stateE)

Sets the fifth part of the state.

Parameters:

stateE - can be any long

setState

public void setState(long stateA,
 long stateB,
 long stateC,
 long stateD,
 long stateE)

Sets the state completely to the given five state variables. This is the same as calling setStateA(long), setStateB(long), setStateC(long), setStateD(long), and setStateE(long) as a group.

Overrides:

setState in class EnhancedRandom

Parameters:

stateA - the first state; can be any long

stateB - the second state; can be any long

stateC - the third state; can be any long

stateD - the fourth state; can be any long

stateE - the fifth state; can be any long

nextLong

public long nextLong()

Description copied from class: EnhancedRandom

Returns the next pseudorandom, uniformly distributed long value from this random number generator's sequence. The general contract of nextLong is that one long value is pseudorandomly generated and returned.
The only methods that need to be implemented by this interface are this and EnhancedRandom.copy(), though other methods can be implemented as appropriate for generators that, for instance, natively produce ints rather than longs.

Specified by:

nextLong in interface RandomGenerator

Specified by:

nextLong in class EnhancedRandom

Returns:

the next pseudorandom, uniformly distributed long value from this random number generator's sequence

next

public int next(int bits)

Description copied from class: EnhancedRandom

Generates the next pseudorandom number with a specific maximum size in bits (not a max number). If you want to get a random number in a range, you should usually use EnhancedRandom.nextInt(int) instead. For some specific cases, this method is more efficient and less biased than EnhancedRandom.nextInt(int). For bits values between 1 and 30, this should be similar in effect to nextInt(1 << bits); though it won't typically produce the same values, they will have the correct range. If bits is 31, this can return any non-negative int; note that nextInt(1 << 31) won't behave this way because 1 << 31 is negative. If bits is 32 (or 0), this can return any int.

The general contract of next is that it returns an int value and if the argument bits is between 1 and 32 (inclusive), then that many low-order bits of the returned value will be (approximately) independently chosen bit values, each of which is (approximately) equally likely to be 0 or 1.

Note that you can give this values for bits that are outside its expected range of 1 to 32, but the value used, as long as bits is positive, will effectively be bits % 32. As stated before, a value of 0 for bits is the same as a value of 32.

Overrides:

next in class EnhancedRandom

Parameters:

bits - the amount of random bits to request, from 1 to 32

Returns:

the next pseudorandom value from this random number generator's sequence

copy

public Crand64Random copy()

Description copied from class: EnhancedRandom

Creates a new EnhancedRandom with identical states to this one, so if the same EnhancedRandom methods are called on this object and its copy (in the same order), the same outputs will be produced. This is not guaranteed to copy the inherited state of any parent class, so if you call methods that are only implemented by a superclass (like Random) and not this one, the results may differ.

Specified by:

copy in class EnhancedRandom

Returns:

a deep copy of this EnhancedRandom.

equals

public boolean equals(Object o)

Overrides:

equals in class Object

toString

public String toString()

Overrides:

toString in class Object