org.apache.commons.math3.random
Class AbstractWell

java.lang.Object
  extended by org.apache.commons.math3.random.BitsStreamGenerator
      extended by org.apache.commons.math3.random.AbstractWell
All Implemented Interfaces:
Serializable, RandomGenerator
Direct Known Subclasses:
Well1024a, Well19937a, Well19937c, Well44497a, Well44497b, Well512a

public abstract class AbstractWell
extends BitsStreamGenerator
implements Serializable

This abstract class implements the WELL class of pseudo-random number generator from François Panneton, Pierre L'Ecuyer and Makoto Matsumoto.

This generator is described in a paper by François Panneton, Pierre L'Ecuyer and Makoto Matsumoto Improved Long-Period Generators Based on Linear Recurrences Modulo 2 ACM Transactions on Mathematical Software, 32, 1 (2006). The errata for the paper are in wellrng-errata.txt.

Since:
2.2
Version:
$Id: AbstractWell.java 1416643 2012-12-03 19:37:14Z tn $
See Also:
WELL Random number generator, Serialized Form

Field Summary
protected  int[] i1
          Index indirection table giving for each index the value index + m1 taking table size into account.
protected  int[] i2
          Index indirection table giving for each index the value index + m2 taking table size into account.
protected  int[] i3
          Index indirection table giving for each index the value index + m3 taking table size into account.
protected  int index
          Current index in the bytes pool.
protected  int[] iRm1
          Index indirection table giving for each index its predecessor taking table size into account.
protected  int[] iRm2
          Index indirection table giving for each index its second predecessor taking table size into account.
protected  int[] v
          Bytes pool.
 
Constructor Summary
protected AbstractWell(int k, int m1, int m2, int m3)
          Creates a new random number generator.
protected AbstractWell(int k, int m1, int m2, int m3, int seed)
          Creates a new random number generator using a single int seed.
protected AbstractWell(int k, int m1, int m2, int m3, int[] seed)
          Creates a new random number generator using an int array seed.
protected AbstractWell(int k, int m1, int m2, int m3, long seed)
          Creates a new random number generator using a single long seed.
 
Method Summary
protected abstract  int next(int bits)
          Generate next pseudorandom number.
 void setSeed(int seed)
          Reinitialize the generator as if just built with the given int seed.
 void setSeed(int[] seed)
          Reinitialize the generator as if just built with the given int array seed.
 void setSeed(long seed)
          Reinitialize the generator as if just built with the given 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
 

Field Detail

index

protected int index
Current index in the bytes pool.


v

protected final int[] v
Bytes pool.


iRm1

protected final int[] iRm1
Index indirection table giving for each index its predecessor taking table size into account.


iRm2

protected final int[] iRm2
Index indirection table giving for each index its second predecessor taking table size into account.


i1

protected final int[] i1
Index indirection table giving for each index the value index + m1 taking table size into account.


i2

protected final int[] i2
Index indirection table giving for each index the value index + m2 taking table size into account.


i3

protected final int[] i3
Index indirection table giving for each index the value index + m3 taking table size into account.

Constructor Detail

AbstractWell

protected AbstractWell(int k,
                       int m1,
                       int m2,
                       int m3)
Creates a new random number generator.

The instance is initialized using the current time plus the system identity hash code of this instance as the seed.

Parameters:
k - number of bits in the pool (not necessarily a multiple of 32)
m1 - first parameter of the algorithm
m2 - second parameter of the algorithm
m3 - third parameter of the algorithm

AbstractWell

protected AbstractWell(int k,
                       int m1,
                       int m2,
                       int m3,
                       int seed)
Creates a new random number generator using a single int seed.

Parameters:
k - number of bits in the pool (not necessarily a multiple of 32)
m1 - first parameter of the algorithm
m2 - second parameter of the algorithm
m3 - third parameter of the algorithm
seed - the initial seed (32 bits integer)

AbstractWell

protected AbstractWell(int k,
                       int m1,
                       int m2,
                       int m3,
                       int[] seed)
Creates a new random number generator using an int array seed.

Parameters:
k - number of bits in the pool (not necessarily a multiple of 32)
m1 - first parameter of the algorithm
m2 - second parameter of the algorithm
m3 - third parameter of the algorithm
seed - the initial seed (32 bits integers array), if null the seed of the generator will be related to the current time

AbstractWell

protected AbstractWell(int k,
                       int m1,
                       int m2,
                       int m3,
                       long seed)
Creates a new random number generator using a single long seed.

Parameters:
k - number of bits in the pool (not necessarily a multiple of 32)
m1 - first parameter of the algorithm
m2 - second parameter of the algorithm
m3 - third parameter of the algorithm
seed - the initial seed (64 bits integer)
Method Detail

setSeed

public void setSeed(int seed)
Reinitialize the generator as if just built with the given int seed.

The state of the generator is exactly the same as a new generator built with the same seed.

Specified by:
setSeed in interface RandomGenerator
Specified by:
setSeed in class BitsStreamGenerator
Parameters:
seed - the initial seed (32 bits integer)

setSeed

public void setSeed(int[] seed)
Reinitialize the generator as if just built with the given int array seed.

The state of the generator is exactly the same as a new generator built with the same seed.

Specified by:
setSeed in interface RandomGenerator
Specified by:
setSeed in class BitsStreamGenerator
Parameters:
seed - the initial seed (32 bits integers array). If null the seed of the generator will be the system time plus the system identity hash code of the instance.

setSeed

public void setSeed(long seed)
Reinitialize the generator as if just built with the given long seed.

The state of the generator is exactly the same as a new generator built with the same seed.

Specified by:
setSeed in interface RandomGenerator
Specified by:
setSeed in class BitsStreamGenerator
Parameters:
seed - the initial seed (64 bits integer)

next

protected abstract 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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