Package sim.util.distribution

Class AbstractDistribution

java.lang.Object
sim.util.distribution.AbstractDistribution
All Implemented Interfaces:
Serializable
Direct Known Subclasses:
AbstractContinuousDistribution, AbstractDiscreteDistribution
public abstract class AbstractDistribution extends Object implements Serializable
Abstract base class for all random distributions. A subclass of this class need to override method nextDouble() and, in rare cases, also nextInt().

Currently all subclasses use a uniform pseudo-random number generation engine and transform its results to the target distribution. Thus, they expect such a uniform engine upon instance construction.

invalid @link 
cern.jet.random.engine.MersenneTwister
is recommended as uniform pseudo-random number generation engine, since it is very strong and at the same time quick.
invalid @link 
#makeDefaultGenerator()
will conveniently construct and return such a magic thing. You can also, for example, use
invalid @link 
cern.jet.random.engine.DRand
, a quicker (but much weaker) uniform random number generation engine. Of course, you can also use other strong uniform random number generation engines.

Ressources on the Web:

Check the Web version of the CERN Data Analysis Briefbook . This will clarify the definitions of most distributions.
Also consult the StatSoft Electronic Textbook - the definite web book.

Other useful ressources:

Another site and yet another site describing the definitions of several distributions.
You may want to check out a Glossary of Statistical Terms.
The GNU Scientific Library contains an extensive (but hardly readable) list of definition of distributions.
Use this Web interface to plot all sort of distributions.
Even more ressources: Internet glossary of Statistical Terms, a text book, another text book.
Finally, a good link list Statistics on the Web.

See Also:
  • invalid @see 
    cern.jet.random.engine
  • invalid @see 
    cern.jet.random.engine.Benchmark
  • invalid @see 
    cern.jet.random.Benchmark
  • Serialized Form

  • Field Details

  • Constructor Details

    • AbstractDistribution

      public AbstractDistribution()

  • Method Details

    • apply

      public double apply(double dummy)
      Equivalent to nextDouble(). This has the effect that distributions can now be used as function objects, returning a random number upon function evaluation.

    • apply

      public int apply(int dummy)
      Equivalent to nextInt(). This has the effect that distributions can now be used as function objects, returning a random number upon function evaluation.

    • getRandomGenerator

      protected MersenneTwisterFast getRandomGenerator()
      Returns the used uniform random number generator;

    • nextDouble

      public abstract double nextDouble()
      Returns a random number from the distribution.

    • nextInt

      public int nextInt()
      Returns a random number from the distribution; returns (int) Math.round(nextDouble()). Override this method if necessary.

    • setRandomGenerator

      protected void setRandomGenerator(MersenneTwisterFast randomGenerator)
      Sets the uniform random generator internally used.