edu.uah.math.distributions
Class WeibullDistribution

java.lang.Object
  edu.uah.math.distributions.Distribution
      edu.uah.math.distributions.WeibullDistribution

All Implemented Interfaces:

java.io.Serializable

public class WeibullDistribution
extends Distribution
implements java.io.Serializable

This class models the Weibull distribution with specified shape and scale parameters.

Version:

August, 2003

Author:

Kyle Siegrist, Dawn Duehring

See Also:

Serialized Form

Field Summary

Fields inherited from class edu.uah.math.distributions.Distribution

CONTINUOUS, DISCRETE, MIXED

Constructor Summary

WeibullDistribution()
This default constructor creates a new Weibull distribution with shape parameter 1 and scale parameter 1.

WeibullDistribution(double k, double b)
This general constructor creates a new Weibull distribution with spcified shape and scale parameters.

Method Summary

double	getCDF(double x) This method computes the cumulative distribution function.
double	getDensity(double x) This method computes the denstiy function.
double	getFailureRate(double x) This method computes the failure rate function.
double	getMaxDensity() This method returns the maximum value of the density function.
double	getMean() The method returns the mean of the distribution.
double	getMoment(double a, int n) This method returns the moment of a specified order about a specified point.
double	getMoment(int n) This method returns the moment of a specified order.
double	getQuantile(double p) This method returns the quantile function
double	getScale() This method returns the scale parameter.
double	getShape() This method returns the shape parameter.
double	getVariance() This method returns the variance of the distribution.
void	setParameters(double k, double b) This method sets the shape and scale parameter.
void	setScale(double b) This method sets the scale parameter.
void	setShape(double k) This method sets the shape parameter.
java.lang.String	toString() This method returns a string that gives the name of the distribution and the values of the parameters.

Methods inherited from class edu.uah.math.distributions.Distribution

getDomain, getMedian, getMGF, getPGF, getSD, getType, setDomain, setDomain, simulate

Methods inherited from class java.lang.Object

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

Constructor Detail

WeibullDistribution

public WeibullDistribution(double k,
                           double b)

This general constructor creates a new Weibull distribution with spcified shape and scale parameters.

Parameters:

k - the shape parameter

b - the scale parameter

WeibullDistribution

public WeibullDistribution()

This default constructor creates a new Weibull distribution with shape parameter 1 and scale parameter 1.

Method Detail

setParameters

public void setParameters(double k,
                          double b)

This method sets the shape and scale parameter. The normalizing constant is computed and the default domain defined.

Parameters:

k - the shape parameter

b - the scale parameter

getDensity

public double getDensity(double x)

This method computes the denstiy function.

Specified by:

getDensity in class Distribution

Parameters:

x - a number in the domain of the distribution

Returns:

the probability density at x

getMaxDensity

public double getMaxDensity()

This method returns the maximum value of the density function.

Overrides:

getMaxDensity in class Distribution

Returns:

the maximum value of the probability density function

getMean

public double getMean()

The method returns the mean of the distribution.

Overrides:

getMean in class Distribution

Returns:

the mean

getVariance

public double getVariance()

This method returns the variance of the distribution.

Overrides:

getVariance in class Distribution

Returns:

the variance

getMoment

public double getMoment(int n)

This method returns the moment of a specified order.

Overrides:

getMoment in class Distribution

Parameters:

n - the order

Returns:

the moment of that order

getMoment

public double getMoment(double a,
                        int n)

This method returns the moment of a specified order about a specified point.

Overrides:

getMoment in class Distribution

Parameters:

a - the center

n - the order

Returns:

the moment of order n about a

getCDF

public double getCDF(double x)

This method computes the cumulative distribution function.

Overrides:

getCDF in class Distribution

Parameters:

x - a number in the domain of the distribution

Returns:

the cumulative distsribution at x.

getQuantile

public double getQuantile(double p)

This method returns the quantile function

Overrides:

getQuantile in class Distribution

Parameters:

p - a number in (0, 1)

Returns:

the quantile of order p

getFailureRate

public double getFailureRate(double x)

This method computes the failure rate function.

Overrides:

getFailureRate in class Distribution

Parameters:

x - a number in the domain of the distribution

Returns:

the failure rate at x

getShape

public double getShape()

This method returns the shape parameter.

Returns:

the shape parameter

setShape

public void setShape(double k)

This method sets the shape parameter.

Parameters:

k - the shape parameter

getScale

public double getScale()

This method returns the scale parameter.

Returns:

the scale parameter

setScale

public void setScale(double b)

This method sets the scale parameter.

Parameters:

b - the scale parameter

toString

public java.lang.String toString()

This method returns a string that gives the name of the distribution and the values of the parameters.

Overrides:

toString in class Distribution

Returns:

a string giving the name of the distribution and the values of the parameters