com.imsl.stat
Class PoissonDistribution

java.lang.Object
  com.imsl.stat.PoissonDistribution

All Implemented Interfaces:

Distribution, ProbabilityDistribution, Serializable

public class PoissonDistribution
extends Object
implements ProbabilityDistribution, Serializable

Evaluates a Poisson probability distribution.

The poissonDistribution evaluates the poisson probability distribution of a given set of data, xData. If parameters are not supplied, the eval method first calculates theta, . The poisson probability distribution is defined as:

See Also:

Serialized Form

Constructor Summary

PoissonDistribution()

Method Summary

double[]	eval(double[] xData) Evaluates a Poisson probability distribution from a given set of data.
double[]	eval(double[] xData, Object[] parameters) Evaluates a Poisson probability distribution from a given set of data.
double	eval(double xData, Object[] parameters) Evaluates a Poisson probability distribution at a given point xData.
Object[]	getParameters() Returns the Parameters used to evaluate the distribution.
double	getTheta() Returns the mean number of successes in a given time period of the Poisson probability distribution.

Methods inherited from class java.lang.Object

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

Constructor Detail

PoissonDistribution

public PoissonDistribution()

Method Detail

eval

public double[] eval(double[] xData)

Evaluates a Poisson probability distribution from a given set of data.

Specified by:

eval in interface Distribution

Parameters:

xData - a double array representing the points at which the Poisson probability distribution function is to evaluate.

Returns:

a double array representing the Poisson probability distribution of xData.

eval

public double[] eval(double[] xData,
                     Object[] parameters)

Evaluates a Poisson probability distribution from a given set of data.

Specified by:

eval in interface ProbabilityDistribution

Parameters:

xData - a double array representing the points at which the Poisson probability distribution function is to evaluate.

parameters - an Object array representing the parameters used to evaluate the poisson distribution.

Returns:

a double array representing the Poisson probability distribution of xData.

eval

public double eval(double xData,
                   Object[] parameters)

Evaluates a Poisson probability distribution at a given point xData.

Specified by:

eval in interface ProbabilityDistribution

Parameters:

xData - a double array representing the points at which the Poisson probability distribution function is to evaluate.

parameters - an Object array representing the parameters used to evaluate the poisson distribution.

Returns:

a double array representing the Poisson probability distribution of xData.

getParameters

public Object[] getParameters()

Returns the Parameters used to evaluate the distribution.

Specified by:

getParameters in interface ProbabilityDistribution

Returns:

an Object array representing the parameters used to evaluate the poisson distribution. This Object array can be retrieved after invoking the eval method with the following signature, double[] eval(double[] xData). This Object array can be used as input later with another set of data to the eval methods that require an Object array of distribution parameters as input.

getTheta

public double getTheta()

Returns the mean number of successes in a given time period of the Poisson probability distribution.

Returns:

a double representing the mean number of successes in a given time period of the Poisson probability distribution.