Package edu.rit.util

Class DefaultRandom

java.lang.Object

edu.rit.util.Random

edu.rit.util.DefaultRandom

All Implemented Interfaces:

Serializable

public class DefaultRandom
extends Random

Class DefaultRandom provides a default pseudorandom number generator (PRNG) designed for use in parallel scientific programming. To create an instance of class DefaultRandom, either use the DefaultRandom() constructor, or use the static getInstance(long) method in class Random.

Class DefaultRandom generates random numbers by hashing successive counter values. The seed initializes the counter. The hash function is defined in W. Press et al., Numerical Recipes: The Art of Scientific Computing, Third Edition (Cambridge University Press, 2007), page 352. The hash function applied to the counter value i is:

x := 3935559000370003845 * i + 2691343689449507681 (mod 2⁶⁴)
x := x xor (x right-shift 21)
x := x xor (x left-shift 37)
x := x xor (x right-shift 4)
x := 4768777513237032717 * x (mod 2⁶⁴)
x := x xor (x left-shift 20)
x := x xor (x right-shift 41)
x := x xor (x left-shift 5)
Return x

(The shift and arithmetic operations are all performed on unsigned 64-bit numbers.)

Version:

30-Mar-2008

Author:

Alan Kaminsky

See Also:

• Serialized Form

Constructor Summary

Constructors

Constructor	Description
DefaultRandom(long seed)	Construct a new PRNG with the given seed.

Method Summary

Modifier and Type	Method	Description
protected long	next()	Return the next 64-bit pseudorandom value in this PRNG's sequence.
protected long	next(long skip)	Return the 64-bit pseudorandom value the given number of positions ahead in this PRNG's sequence.
void	setSeed(long seed)	Set this PRNG's seed.

Methods inherited from class edu.rit.util.Random

getInstance, getInstance, nextBoolean, nextBoolean, nextByte, nextByte, nextCharacter, nextCharacter, nextDouble, nextDouble, nextFloat, nextFloat, nextInt, nextInt, nextInteger, nextInteger, nextLong, nextLong, nextShort, nextShort, nextUnsignedByte, nextUnsignedByte, nextUnsignedShort, nextUnsignedShort, skip, skip

Methods inherited from class java.lang.Object

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

Constructor Details

DefaultRandom

public DefaultRandom(long seed)

Construct a new PRNG with the given seed. Any seed value is allowed.

Parameters:

seed - Seed.

Method Details

setSeed

public void setSeed(long seed)

Set this PRNG's seed.

Note: Depending on the PRNG algorithm, certain seed values may not be allowed. See the PRNG algorithm subclass for further information. Set this PRNG's seed. Any seed value is allowed.

Specified by:

setSeed in class Random

Parameters:

seed - Seed.

next

protected long next()

Return the next 64-bit pseudorandom value in this PRNG's sequence.

Specified by:

next in class Random

Returns:

Pseudorandom value.

next

protected long next(long skip)

Return the 64-bit pseudorandom value the given number of positions ahead in this PRNG's sequence. Return the 64-bit pseudorandom value the given number of positions ahead in this PRNG's sequence.

Specified by:

next in class Random

Parameters:

skip - Number of positions to skip, assumed to be > 0.

Returns:

Pseudorandom value.