org.apache.commons.math3.random
Class ISAACRandom

java.lang.Object
  extended by org.apache.commons.math3.random.BitsStreamGenerator
      extended by 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
Version:
$Id: ISAACRandom.java 1416643 2012-12-03 19:37:14Z tn $
See Also:
Serialized Form

Constructor Summary
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
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 org.apache.commons.math3.random.BitsStreamGenerator
clear, nextBoolean, nextBytes, nextDouble, nextFloat, nextGaussian, nextInt, nextInt, nextLong
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

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 Detail

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


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