Package org.apache.commons.math3.random

Class BitsStreamGenerator

java.lang.Object
org.apache.commons.math3.random.BitsStreamGenerator
All Implemented Interfaces:
Serializable, RandomGenerator
Direct Known Subclasses:
AbstractWell, ISAACRandom, MersenneTwister
public abstract class BitsStreamGenerator extends Object implements RandomGenerator, Serializable
Base class for random number generators that generates bits streams.
Since:
2.0
See Also:

  • Constructor Summary

    Constructors
    Constructor
    Description
    BitsStreamGenerator()
    Creates a new random number generator.

  • Method Summary

    Modifier and Type
    Method
    Description
    void
    clear()
    Clears the cache used by the default implementation of nextGaussian.
    protected abstract int
    next(int bits)
    Generate next pseudorandom number.
    boolean
    nextBoolean()
    Returns the next pseudorandom, uniformly distributed boolean value from this random number generator's sequence.
    void
    nextBytes(byte[] bytes)
    Generates random bytes and places them into a user-supplied array.
    void
    nextBytes(byte[] bytes, int start, int len)
    Generates random bytes and places them into a user-supplied array.
    double
    nextDouble()
    Returns the next pseudorandom, uniformly distributed double value between 0.0 and 1.0 from this random number generator's sequence.
    float
    nextFloat()
    Returns the next pseudorandom, uniformly distributed float value between 0.0 and 1.0 from this random number generator's sequence.
    double
    nextGaussian()
    Returns the next pseudorandom, Gaussian ("normally") distributed double value with mean 0.0 and standard deviation 1.0 from this random number generator's sequence.
    int
    nextInt()
    Returns the next pseudorandom, uniformly distributed int value from this random number generator's sequence.
    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()
    Returns the next pseudorandom, uniformly distributed long value from this random number generator's sequence.
    long
    nextLong(long n)
    Returns a pseudorandom, uniformly distributed long value between 0 (inclusive) and the specified value (exclusive), drawn from this random number generator's sequence.
    abstract void
    setSeed(int seed)
    Sets the seed of the underlying random number generator using an int seed.
    abstract void
    setSeed(int[] seed)
    Sets the seed of the underlying random number generator using an int array seed.
    abstract void
    setSeed(long seed)
    Sets the seed of the underlying random number generator using a long seed.

    Methods inherited from class java.lang.Object

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

  • Constructor Details

    • BitsStreamGenerator

      public BitsStreamGenerator()
      Creates a new random number generator.

  • Method Details

    • setSeed

      public abstract 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
      Parameters:
      seed - the seed value

    • setSeed

      public abstract 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
      Parameters:
      seed - the seed value

    • setSeed

      public abstract 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
      Parameters:
      seed - the seed value

    • 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 nextBoolean(), nextBytes(byte[]), nextDouble(), nextFloat(), nextGaussian(), nextInt(), next(int) and nextLong().

      Parameters:
      bits - number of random bits to produce
      Returns:
      random bits generated

    • nextBoolean

      public boolean nextBoolean()
      Returns the next pseudorandom, uniformly distributed boolean value from this random number generator's sequence.
      Specified by:
      nextBoolean in interface RandomGenerator
      Returns:
      the next pseudorandom, uniformly distributed boolean value from this random number generator's sequence

    • nextDouble

      public double nextDouble()
      Returns the next pseudorandom, uniformly distributed double value between 0.0 and 1.0 from this random number generator's sequence.
      Specified by:
      nextDouble in interface RandomGenerator
      Returns:
      the next pseudorandom, uniformly distributed double value between 0.0 and 1.0 from this random number generator's sequence

    • nextFloat

      public float nextFloat()
      Returns the next pseudorandom, uniformly distributed float value between 0.0 and 1.0 from this random number generator's sequence.
      Specified by:
      nextFloat in interface RandomGenerator
      Returns:
      the next pseudorandom, uniformly distributed float value between 0.0 and 1.0 from this random number generator's sequence

    • nextGaussian

      public double nextGaussian()
      Returns the next pseudorandom, Gaussian ("normally") distributed double value with mean 0.0 and standard deviation 1.0 from this random number generator's sequence.
      Specified by:
      nextGaussian in interface RandomGenerator
      Returns:
      the next pseudorandom, Gaussian ("normally") distributed double value with mean 0.0 and standard deviation 1.0 from this random number generator's sequence

    • nextInt

      public int nextInt()
      Returns the next pseudorandom, uniformly distributed int value from this random number generator's sequence. All 232 possible int values should be produced with (approximately) equal probability.
      Specified by:
      nextInt in interface RandomGenerator
      Returns:
      the next pseudorandom, uniformly distributed int value from this random number generator's sequence

    • nextInt

      public int nextInt(int n) throws IllegalArgumentException
      Returns a pseudorandom, uniformly distributed int value between 0 (inclusive) and the specified value (exclusive), drawn from this random number generator's sequence.

      This default implementation is copied from Apache Harmony java.util.Random (r929253).

      Implementation notes:

      • If n is a power of 2, this method returns (int) ((n * (long) next(31)) >> 31).
      • If n is not a power of 2, what is returned is next(31) % n with next(31) values rejected (i.e. regenerated) until a value that is larger than the remainder of Integer.MAX_VALUE / n is generated. Rejection of this initial segment is necessary to ensure a uniform distribution.

      Specified by:
      nextInt in interface RandomGenerator
      Parameters:
      n - the bound on the random number to be returned. Must be positive.
      Returns:
      a pseudorandom, uniformly distributed int value between 0 (inclusive) and n (exclusive).
      Throws:
      IllegalArgumentException - if n is not positive.

    • nextLong

      public long nextLong()
      Returns the next pseudorandom, uniformly distributed long value from this random number generator's sequence. All 264 possible long values should be produced with (approximately) equal probability.
      Specified by:
      nextLong in interface RandomGenerator
      Returns:
      the next pseudorandom, uniformly distributed long value from this random number generator's sequence

    • nextLong

      public long nextLong(long n) throws IllegalArgumentException
      Returns a pseudorandom, uniformly distributed long value between 0 (inclusive) and the specified value (exclusive), drawn from this random number generator's sequence.
      Parameters:
      n - the bound on the random number to be returned. Must be positive.
      Returns:
      a pseudorandom, uniformly distributed long value between 0 (inclusive) and n (exclusive).
      Throws:
      IllegalArgumentException - if n is not positive.

    • clear

      public void clear()
      Clears the cache used by the default implementation of nextGaussian.

    • nextBytes

      public void nextBytes(byte[] bytes)
      Generates random bytes and places them into a user-supplied array.

      The array is filled with bytes extracted from random integers. This implies that the number of random bytes generated may be larger than the length of the byte array.

      Specified by:
      nextBytes in interface RandomGenerator
      Parameters:
      bytes - Array in which to put the generated bytes. Cannot be null.

    • nextBytes

      public void nextBytes(byte[] bytes, int start, int len)
      Generates random bytes and places them into a user-supplied array.

      The array is filled with bytes extracted from random integers. This implies that the number of random bytes generated may be larger than the length of the byte array.

      Parameters:
      bytes - Array in which to put the generated bytes. Cannot be null.
      start - Index at which to start inserting the generated bytes.
      len - Number of bytes to insert.
      Throws:
      OutOfRangeException - if start < 0 or start >= bytes.length.
      OutOfRangeException - if len < 0 or len > bytes.length - start.