umontreal.iro.lecuyer.randvar

Class LogarithmicGen

java.lang.Object

umontreal.iro.lecuyer.randvar.RandomVariateGen

umontreal.iro.lecuyer.randvar.RandomVariateGenInt

umontreal.iro.lecuyer.randvar.LogarithmicGen

public class LogarithmicGen
extends RandomVariateGenInt

This class implements random variate generators for the (discrete) logarithmic distribution. Its mass function is

p(x) = -θ^x/x log(1-θ) for x = 1, 2,…,

where 0 < θ < 1. It uses inversion with the LS chop-down algorithm if θ < θ₀ and the LK transformation algorithm if θ >= θ₀, as described in. The threshold θ₀ can be specified when invoking the constructor. Its default value is θ₀ = 0.96, as suggested in.

A local copy of the parameter θ is maintained in this class.

Constructor Summary

Constructors

Constructor and Description
LogarithmicGen(RandomStream s, double theta) Creates a logarithmic random variate generator with parameters θ = theta and default value θ0 = 0.96, using stream s.
LogarithmicGen(RandomStream s, double theta, double theta0) Creates a logarithmic random variate generator with parameters θ = theta and θ0 = theta0, using stream s.
LogarithmicGen(RandomStream s, LogarithmicDist dist) Creates a new generator with distribution dist and stream s, with default value θ0 = 0.96.
LogarithmicGen(RandomStream s, LogarithmicDist dist, double theta0) Creates a new generator with distribution dist and stream s, with θ0 = theta0.

Method Summary

Modifier and Type	Method and Description
double	getTheta() Returns the θ associated with this object.
double	getTheta0() Returns the θ0 associated with this object.
int	nextInt() Generates a random number (an integer) from the discrete distribution contained in this object.
static int	nextInt(RandomStream s, double theta) Uses stream s to generate a new variate from the logarithmic distribution with parameter θ = theta.

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

getDistribution, nextArrayOfInt

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

getStream, nextArrayOfDouble, nextDouble, setStream, toString

Methods inherited from class java.lang.Object

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

Constructor Detail

LogarithmicGen

public LogarithmicGen(RandomStream s,
                      double theta)

Creates a logarithmic random variate generator with parameters θ = theta and default value θ₀ = 0.96, using stream s.

LogarithmicGen

public LogarithmicGen(RandomStream s,
                      double theta,
                      double theta0)

Creates a logarithmic random variate generator with parameters θ = theta and θ₀ = theta0, using stream s.

LogarithmicGen

public LogarithmicGen(RandomStream s,
                      LogarithmicDist dist)

Creates a new generator with distribution dist and stream s, with default value θ₀ = 0.96.

LogarithmicGen

public LogarithmicGen(RandomStream s,
                      LogarithmicDist dist,
                      double theta0)

Creates a new generator with distribution dist and stream s, with θ₀ = theta0.

Method Detail

nextInt

public int nextInt()

Description copied from class: RandomVariateGenInt

Generates a random number (an integer) from the discrete 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:

nextInt in class RandomVariateGenInt

Returns:

the generated value

nextInt

public static int nextInt(RandomStream s,
                          double theta)

Uses stream s to generate a new variate from the logarithmic distribution with parameter θ = theta.

getTheta

public double getTheta()

Returns the θ associated with this object.

getTheta0

public double getTheta0()

Returns the θ₀ associated with this object.