Class ISAACRandom

java.lang.Object

org.apache.commons.math3.random.BitsStreamGenerator

org.apache.commons.math3.random.ISAACRandom

All Implemented Interfaces:

Serializable, RandomGenerator

public class ISAACRandom
extends BitsStreamGenerator
implements Serializable

ISAAC: a fast cryptographic pseudo-random number generator
ISAAC (Indirection, Shift, Accumulate, Add, and Count) generates 32-bit random numbers. ISAAC has been designed to be cryptographically secure and is inspired by RC4. Cycles are guaranteed to be at least 2⁴⁰ values long, and they are 2⁸²⁹⁵ values long on average. The results are uniformly distributed, unbiased, and unpredictable unless you know the seed.
This code is based (with minor changes and improvements) on the original implementation of the algorithm by Bob Jenkins.

Since:

3.0

See Also:

• Serialized Form

Constructor Summary

Constructors

Constructor	Description
ISAACRandom()	Creates a new ISAAC random number generator.
ISAACRandom(int[] seed)	Creates a new ISAAC random number generator using an int array seed.
ISAACRandom(long seed)	Creates a new ISAAC random number generator using a single long seed.

Method Summary

Modifier and Type	Method	Description
protected int	next(int bits)	Generate next pseudorandom number.
void	setSeed(int seed)	Sets the seed of the underlying random number generator using an int seed.
void	setSeed(int[] seed)	Sets the seed of the underlying random number generator using an int array seed.
void	setSeed(long seed)	Sets the seed of the underlying random number generator using a long seed.

Methods inherited from class BitsStreamGenerator

clear, nextBoolean, nextBytes, nextBytes, nextDouble, nextFloat, nextGaussian, nextInt, nextInt, nextLong, nextLong

Methods inherited from class Object

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

Constructor Details

ISAACRandom

public ISAACRandom()

Creates a new ISAAC random number generator.
The instance is initialized using a combination of the current time and system hash code of the instance as the seed.

ISAACRandom

public ISAACRandom(long seed)

Creates a new ISAAC random number generator using a single long seed.

Parameters:

seed - Initial seed.

ISAACRandom

public ISAACRandom(int[] seed)

Creates a new ISAAC random number generator using an int array seed.

Parameters:

seed - Initial seed. If null, the seed will be related to the current time.

Method Details

setSeed

public void setSeed(int seed)

Sets the seed of the underlying random number generator using an int seed.

Sequences of values generated starting with the same seeds should be identical.

Specified by:

setSeed in interface RandomGenerator

Specified by:

setSeed in class BitsStreamGenerator

Parameters:

seed - the seed value

setSeed

public void setSeed(long seed)

Sets the seed of the underlying random number generator using a long seed.

Sequences of values generated starting with the same seeds should be identical.

Specified by:

setSeed in interface RandomGenerator

Specified by:

setSeed in class BitsStreamGenerator

Parameters:

seed - the seed value

setSeed

public void setSeed(int[] seed)

Sets the seed of the underlying random number generator using an int array seed.

Sequences of values generated starting with the same seeds should be identical.

Specified by:

setSeed in interface RandomGenerator

Specified by:

setSeed in class BitsStreamGenerator

Parameters:

seed - the seed value

next

protected int next(int bits)

Generate next pseudorandom number.

This method is the core generation algorithm. It is used by all the public generation methods for the various primitive types BitsStreamGenerator.nextBoolean(), BitsStreamGenerator.nextBytes(byte[]), BitsStreamGenerator.nextDouble(), BitsStreamGenerator.nextFloat(), BitsStreamGenerator.nextGaussian(), BitsStreamGenerator.nextInt(), BitsStreamGenerator.next(int) and BitsStreamGenerator.nextLong().

Specified by:

next in class BitsStreamGenerator

Parameters:

bits - number of random bits to produce

Returns:

random bits generated