it.unimi.dsi.util

Class XorShift64StarRandom

java.lang.Object

java.util.Random

it.unimi.dsi.util.XorShift64StarRandom

All Implemented Interfaces:

Serializable

Deprecated.

Use SplitMix64Random instead.

@Deprecated
public class XorShift64StarRandom
extends Random

A fast, good-quality pseudorandom number generator that combines George Marsaglia's Xorshift generators (described in “Xorshift RNGs”, Journal of Statistical Software, 8:1−6, 2003) with a multiplication.

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
XorShift64StarRandom() Deprecated. Creates a new generator seeded using Util.randomSeed().
XorShift64StarRandom(long seed) Deprecated. Creates a new generator using a given seed.

Method Summary

Modifier and Type	Method and Description
protected int	next(int bits) Deprecated.
boolean	nextBoolean() Deprecated.
void	nextBytes(byte[] bytes) Deprecated.
double	nextDouble() Deprecated.
float	nextFloat() Deprecated.
int	nextInt() Deprecated.
int	nextInt(int n) Deprecated. Returns a pseudorandom, approximately uniformly distributed int value between 0 (inclusive) and the specified value (exclusive), drawn from this random number generator's sequence.
long	nextLong() Deprecated.
long	nextLong(long n) Deprecated. Returns a pseudorandom uniformly distributed long value between 0 (inclusive) and the specified value (exclusive), drawn from this random number generator's sequence.
void	setSeed(long seed) Deprecated. Sets the seed of this generator.
void	setState(long state) Deprecated. Sets the state of this generator.

Methods inherited from class java.util.Random

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

Methods inherited from class java.lang.Object

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

Constructor Detail

XorShift64StarRandom

public XorShift64StarRandom()

Deprecated.

Creates a new generator seeded using Util.randomSeed().

XorShift64StarRandom

public XorShift64StarRandom(long seed)

Deprecated.

Creates a new generator using a given seed.

Parameters:

seed - a nonzero seed for the generator (if zero, the generator will be seeded with -1).

Method Detail

next

protected int next(int bits)

Deprecated.

Overrides:

next in class Random

nextLong

public long nextLong()

Deprecated.

Overrides:

nextLong in class Random

nextInt

public int nextInt()

Deprecated.

Overrides:

nextInt in class Random

nextInt

public int nextInt(int n)

Deprecated.

Returns a pseudorandom, approximately uniformly distributed int value between 0 (inclusive) and the specified value (exclusive), drawn from this random number generator's sequence.

The hedge “approximately” is due to the fact that to be always faster than ThreadLocalRandom we return the upper 63 bits of nextLong() modulo n instead of using Random's fancy algorithm (which nextLong(long) uses though). This choice introduces a bias: the numbers from 0 to 2⁶³ mod n are slightly more likely than the other ones. In the worst case, “more likely” means 1.00000000023 times more likely, which is in practice undetectable (actually, due to the abysmally low quality of Random's generator, the result is statistically better in any case than Random.nextInt(int)'s) .

If for some reason you need truly uniform generation, just use nextLong(long).

Overrides:

nextInt in class Random

Parameters:

n - the positive bound on the random number to be returned.

Returns:

the next pseudorandom int value between 0 (inclusive) and n (exclusive).

nextLong

public long nextLong(long n)

Deprecated.

Returns a pseudorandom uniformly distributed long value between 0 (inclusive) and the specified value (exclusive), drawn from this random number generator's sequence. The algorithm used to generate the value guarantees that the result is uniform, provided that the sequence of 64-bit values produced by this generator is.

Parameters:

n - the positive bound on the random number to be returned.

Returns:

the next pseudorandom long value between 0 (inclusive) and n (exclusive).

nextDouble

public double nextDouble()

Deprecated.

Overrides:

nextDouble in class Random

nextFloat

public float nextFloat()

Deprecated.

Overrides:

nextFloat in class Random

nextBoolean

public boolean nextBoolean()

Deprecated.

Overrides:

nextBoolean in class Random

nextBytes

public void nextBytes(byte[] bytes)

Deprecated.

Overrides:

nextBytes in class Random

setSeed

public void setSeed(long seed)

Deprecated.

Sets the seed of this generator.

The seed will be passed through HashCommon.murmurHash3(long). In this way, if the user passes a small value we will avoid the short irregular transient associated with states with a very small number of bits set.

Overrides:

setSeed in class Random

Parameters:

seed - a nonzero seed for this generator (if zero, the generator will be seeded with Long.MIN_VALUE).

setState

public void setState(long state)

Deprecated.

Sets the state of this generator.

Parameters:

state - the new state for this generator (must be nonzero).