umontreal.iro.lecuyer.randvar
Class ErlangGen

java.lang.Object
  umontreal.iro.lecuyer.randvar.RandomVariateGen
      umontreal.iro.lecuyer.randvar.ErlangGen

Direct Known Subclasses:

ErlangConvolutionGen

public class ErlangGen
extends RandomVariateGen

This class implements random variate generators for the Erlang distribution with parameters k > 0 and λ > 0. This Erlang random variable is the sum of k exponentials with parameter λ and has mean k/λ. Erlang random variates can also be obtained by generators from the gamma distribution.

No local copy of the parameters k and λ is maintained in this class. The (non-static) nextDouble method simply calls inverseF on the distribution.

Constructor Summary

ErlangGen(RandomStream s, ErlangDist dist)
Creates a new generator for the distribution dist and stream s.

Method Summary

double	nextDouble() Generates a random number from the continuous distribution contained in this object.
static double	nextDouble(RandomStream s, int k, double lambda) Generates a new variate from the Erlang distribution with parameters k = k and λ = lambda, using stream s.

Methods inherited from class umontreal.iro.lecuyer.randvar.RandomVariateGen

getDistribution, getStream, nextArrayOfDouble

Methods inherited from class java.lang.Object

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

Constructor Detail

ErlangGen

public ErlangGen(RandomStream s,
                 ErlangDist dist)

Creates a new generator for the distribution dist and stream s.

Method Detail

nextDouble

public double nextDouble()

Description copied from class: RandomVariateGen

Generates a random number from the continuous distribution contained in this object. By default, this method uses inversion by calling the inverseF method of the distribution object. Alternative generating methods are provided in subclasses.

Overrides:

nextDouble in class RandomVariateGen

Returns:

the generated value

nextDouble

public static double nextDouble(RandomStream s,
                                int k,
                                double lambda)

Generates a new variate from the Erlang distribution with parameters k = k and λ = lambda, using stream s.