Package cern.jet.random.engine

Class RandomEngine

  • All Implemented Interfaces:
    DoubleFunction, IntFunction, Serializable, Cloneable
    Direct Known Subclasses:
    DRand, MersenneTwister
    public abstract class RandomEngine
extends PersistentObject
implements DoubleFunction, IntFunction
    Abstract base class for uniform pseudo-random number generating engines.

    Most probability distributions are obtained by using a uniform pseudo-random number generation engine followed by a transformation to the desired distribution. Thus, subclasses of this class are at the core of computational statistics, simulations, Monte Carlo methods, etc.

    Subclasses produce uniformly distributed int's and long's in the closed intervals [Integer.MIN_VALUE,Integer.MAX_VALUE] and [Long.MIN_VALUE,Long.MAX_VALUE], respectively, as well as float's and double's in the open unit intervals (0.0f,1.0f) and (0.0,1.0), respectively.

    Subclasses need to override one single method only: nextInt(). All other methods generating different data types or ranges are usually layered upon nextInt(). long's are formed by concatenating two 32 bit int's. float's are formed by dividing the interval [0.0f,1.0f] into 232 sub intervals, then randomly choosing one subinterval. double's are formed by dividing the interval [0.0,1.0] into 264 sub intervals, then randomly choosing one subinterval.

    Note that this implementation is not synchronized.

    Version:
    1.0, 09/24/99
    Author:
    wolfgang.hoschek@cern.ch
    See Also:
    MersenneTwister, Random, Serialized Form

    • Constructor Summary

      Constructors 
      Modifier Constructor Description
      protected RandomEngine()
      Makes this class non instantiable, but still let's others inherit from it.

    • Method Summary

      All Methods Static Methods Instance Methods Abstract Methods Concrete Methods 
      Modifier and Type Method Description
      double apply​(double dummy)
      Equivalent to raw().
      int apply​(int dummy)
      Equivalent to nextInt().
      static RandomEngine makeDefault()
      Constructs and returns a new uniform random number engine seeded with the current time.
      double nextDouble()
      Returns a 64 bit uniformly distributed random number in the open unit interval (0.0,1.0) (excluding 0.0 and 1.0).
      float nextFloat()
      Returns a 32 bit uniformly distributed random number in the open unit interval (0.0f,1.0f) (excluding 0.0f and 1.0f).
      abstract int nextInt()
      Returns a 32 bit uniformly distributed random number in the closed interval [Integer.MIN_VALUE,Integer.MAX_VALUE] (including Integer.MIN_VALUE and Integer.MAX_VALUE);
      long nextLong()
      Returns a 64 bit uniformly distributed random number in the closed interval [Long.MIN_VALUE,Long.MAX_VALUE] (including Long.MIN_VALUE and Long.MAX_VALUE).
      double raw()
      Returns a 32 bit uniformly distributed random number in the open unit interval (0.0,1.0) (excluding 0.0 and 1.0).

    • Constructor Detail

      • RandomEngine

        protected RandomEngine()
        Makes this class non instantiable, but still let's others inherit from it.

    • Method Detail

      • apply

        public double apply​(double dummy)
        Equivalent to raw(). This has the effect that random engines can now be used as function objects, returning a random number upon function evaluation.
        Specified by:
        apply in interface DoubleFunction
        Parameters:
        dummy - argument passed to the function.
        Returns:
        the result of the function.

      • apply

        public int apply​(int dummy)
        Equivalent to nextInt(). This has the effect that random engines can now be used as function objects, returning a random number upon function evaluation.
        Specified by:
        apply in interface IntFunction
        Parameters:
        dummy - argument passed to the function.
        Returns:
        the result of the function.

      • makeDefault

        public static RandomEngine makeDefault()
        Constructs and returns a new uniform random number engine seeded with the current time. Currently this is MersenneTwister.

      • nextDouble

        public double nextDouble()
        Returns a 64 bit uniformly distributed random number in the open unit interval (0.0,1.0) (excluding 0.0 and 1.0).

      • nextFloat

        public float nextFloat()
        Returns a 32 bit uniformly distributed random number in the open unit interval (0.0f,1.0f) (excluding 0.0f and 1.0f).

      • nextInt

        public abstract int nextInt()
        Returns a 32 bit uniformly distributed random number in the closed interval [Integer.MIN_VALUE,Integer.MAX_VALUE] (including Integer.MIN_VALUE and Integer.MAX_VALUE);

      • nextLong

        public long nextLong()
        Returns a 64 bit uniformly distributed random number in the closed interval [Long.MIN_VALUE,Long.MAX_VALUE] (including Long.MIN_VALUE and Long.MAX_VALUE).

      • raw

        public double raw()
        Returns a 32 bit uniformly distributed random number in the open unit interval (0.0,1.0) (excluding 0.0 and 1.0).