de.unihalle.informatik.MiToBo.math.distributions.impl

Class PoissonDistribution

java.lang.Object

de.unihalle.informatik.MiToBo.math.distributions.impl.PoissonDistribution

All Implemented Interfaces:

ConditionalDistribution<Double>, EvaluatableDistribution<Integer>, FirstOrderMoment<Double>, LogEvaluatableDistribution<Integer>, LogProbabilityMassFunction, ProbabilityMassFunction, SamplingDistribution<Integer>, SecondOrderCentralMoment<Double>

public class PoissonDistribution
extends Object
implements ProbabilityMassFunction, LogProbabilityMassFunction, ConditionalDistribution<Double>, FirstOrderMoment<Double>, SecondOrderCentralMoment<Double>, SamplingDistribution<Integer>

Poisson distribution.

Author:

Oliver Gress

Field Summary

Fields

Modifier and Type	Field and Description
protected double	lambda mean=variance of the distribution
protected Random	rand

Constructor Summary

Constructors

Constructor and Description
PoissonDistribution(double lambda, Random rand) Constructor for Poisson distribution with parameter lambda (=mean=variance)

Method Summary

Modifier and Type	Method and Description
Integer	drawSample() Generate a new sample from this density.
Double	getCondition() Get conditional variable
Double	getCovariance()
Double	getMean()
double	log_p(Integer k) Evaluate natural logarithm of p(X) at location x. log(P(X=x))
double	p(Integer k) Evaluate p(X) at location x.
void	setCondition(Double lambda) Set the conditional variable

Methods inherited from class java.lang.Object

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

Field Detail

lambda

protected double lambda

mean=variance of the distribution

rand

protected Random rand

Constructor Detail

PoissonDistribution

public PoissonDistribution(double lambda,
                           Random rand)

Constructor for Poisson distribution with parameter lambda (=mean=variance)

Parameters:

lambda - mean/variance of the distribution

rand - random generator for sampling

Method Detail

p

public double p(Integer k)

Description copied from interface: EvaluatableDistribution

Evaluate p(X) at location x. P(X=x)

Specified by:

p in interface EvaluatableDistribution<Integer>

Parameters:

k - realization of random variable X

Returns:

value of p(X) at x

log_p

public double log_p(Integer k)

Description copied from interface: LogEvaluatableDistribution

Evaluate natural logarithm of p(X) at location x. log(P(X=x))

Specified by:

log_p in interface LogEvaluatableDistribution<Integer>

Parameters:

k - realization of random variable X

Returns:

value of log(p(X)) at x

getCovariance

public Double getCovariance()

Specified by:

getCovariance in interface SecondOrderCentralMoment<Double>

getMean

public Double getMean()

Specified by:

getMean in interface FirstOrderMoment<Double>

getCondition

public Double getCondition()

Description copied from interface: ConditionalDistribution

Get conditional variable

Specified by:

getCondition in interface ConditionalDistribution<Double>

Returns:

object which specifies the condition

setCondition

public void setCondition(Double lambda)

Description copied from interface: ConditionalDistribution

Set the conditional variable

Specified by:

setCondition in interface ConditionalDistribution<Double>

Parameters:

lambda - conditional variable

drawSample

public Integer drawSample()

Description copied from interface: SamplingDistribution

Generate a new sample from this density. This method should create a new object.

Specified by:

drawSample in interface SamplingDistribution<Integer>

Returns:

new sample object