de.lmu.ifi.dbs.elki.utilities.random

Class XorShift1024NonThreadsafeRandom

java.lang.Object

java.util.Random

de.lmu.ifi.dbs.elki.utilities.random.XorShift1024NonThreadsafeRandom

All Implemented Interfaces:

java.io.Serializable

@Reference(authors="S. Vigna",
           title="An experimental exploration of Marsaglia\'s xorshift generators, scrambled",
           booktitle="Online",
           url="http://vigna.di.unimi.it/ftp/papers/xorshift.pdf",
           bibkey="web/Vigna14")
public class XorShift1024NonThreadsafeRandom
extends java.util.Random

Replacement for Java's Random class, using a different random number generation strategy. Java's random generator is optimized for speed, but may lack the randomness needed for more complex experiments.

This approach is based on the work on XorShift1024* by Sebastiano Vigna, with the original copyright statement:

Written in 2014 by Sebastiano Vigna (vigna@acm.org)

To the extent possible under law, the author has dedicated all copyright and related and neighboring rights to this software to the public domain worldwide. This software is distributed without any warranty.

See http://creativecommons.org/publicdomain/zero/1.0/

Since:

0.7.0

Author:

Erich Schubert

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected static java.lang.String	BADBOUND Exception message for non-positive bounds
(package private) int	p For rotating amongst states
private static long	serialVersionUID Serial version number.
private long[]	x State of random number generator.

Constructor Summary

Constructors

Constructor and Description
XorShift1024NonThreadsafeRandom() Constructor called only by localRandom.initialValue.
XorShift1024NonThreadsafeRandom(long seed) Constructor.

Method Summary

Modifier and Type	Method and Description
protected int	next(int bits)
double	nextDouble()
int	nextInt()
int	nextInt(int n) Returns a pseudorandom, uniformly distributed int value between 0 (inclusive) and the specified value (exclusive), drawn from this random number generator's sequence.
long	nextLong()
void	setSeed(long seed)

Methods inherited from class java.util.Random

doubles, doubles, doubles, doubles, ints, ints, ints, ints, longs, longs, longs, longs, nextBoolean, nextBytes, nextFloat, nextGaussian

Methods inherited from class java.lang.Object

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

Field Detail

serialVersionUID

private static final long serialVersionUID

Serial version number.

See Also:

Constant Field Values

x

private long[] x

State of random number generator.

p

int p

For rotating amongst states

BADBOUND

protected static final java.lang.String BADBOUND

Exception message for non-positive bounds

See Also:

Constant Field Values

Constructor Detail

XorShift1024NonThreadsafeRandom

public XorShift1024NonThreadsafeRandom()

Constructor called only by localRandom.initialValue.

XorShift1024NonThreadsafeRandom

public XorShift1024NonThreadsafeRandom(long seed)

Constructor.

Parameters:

seed - Random generator seed.

Method Detail

setSeed

public void setSeed(long seed)

Overrides:

setSeed in class java.util.Random

nextLong

public long nextLong()

Overrides:

nextLong in class java.util.Random

next

protected int next(int bits)

Overrides:

next in class java.util.Random

nextInt

public int nextInt()

Overrides:

nextInt in class java.util.Random

nextDouble

public double nextDouble()

Overrides:

nextDouble in class java.util.Random

nextInt

@Reference(authors="D. Lemire",
           title="Fast random shuffling",
           booktitle="Daniel Lemire\'s blog",
           url="http://lemire.me/blog/2016/06/30/fast-random-shuffling/",
           bibkey="blog/Lemire16")
public int nextInt(int n)

Returns a pseudorandom, uniformly distributed int value between 0 (inclusive) and the specified value (exclusive), drawn from this random number generator's sequence. The general contract of nextInt is that one int value in the specified range is pseudorandomly generated and returned. All n possible int values are produced with (approximately) equal probability.

In contrast to the Java version, we use an approach that tries to avoid divisions for performance discussed in:

D. Lemire
Fast random shuffling
http://lemire.me/blog/2016/06/30/fast-random-shuffling/

Overrides:

nextInt in class java.util.Random