javanpst.distributions.common.continuous

Class GammaDistribution

java.lang.Object

javanpst.distributions.common.continuous.GammaDistribution

All Implemented Interfaces:

Distribution

public final class GammaDistribution
extends java.lang.Object
implements Distribution

A Gamma distribution.

Constructor Summary

Constructors

Constructor and Description
GammaDistribution() Default builder.
GammaDistribution(double alpha, double beta) Builder.
GammaDistribution(GammaDistribution old) Copy constructor Creates a copy of a given gamma distribution

Method Summary

Modifier and Type	Method and Description
double	computeCumulativeProbability(double value) Computes cumulative probability at a given point of the gamma distribution.
double	computeProbability(double value) Computes mass probability at a given point of the gamma distribution.
double	getAlpha() Gets the alpha parameter
double	getBeta() Gets the beta parameter
double	getK() Gets the K parameter (an alias of alpha)
double	getLambda() Gets the lambda parameter (an alias of 1/beta)
double	regularizedGammaP(double a, double x) Computes regularized gamma P function
double	regularizedGammaQ(double a, double x) Computes regularized gamma Q function
void	setAlpha(double value) Sets alpha value Value must be positive
void	setBeta(double value) Sets beta value Value must be positive
void	setK(double value) Sets K value (an alias of alpha) Value must be positive
void	setLambda(double value) Sets lambda value (an alias of (1/beta)) Value must be positive
java.lang.String	toString() To String method.

Methods inherited from class java.lang.Object

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

Constructor Detail

GammaDistribution

public GammaDistribution()

Default builder. Creates a chi-square distribution with 1 degree of freedom

GammaDistribution

public GammaDistribution(double alpha,
                         double beta)

Builder. Creates a gamma distribution with specified values of alpha and beta

Parameters:

alpha -

beta -

GammaDistribution

public GammaDistribution(GammaDistribution old)

Copy constructor Creates a copy of a given gamma distribution

Parameters:

old - uniform distribution to copy

Method Detail

setAlpha

public void setAlpha(double value)

Sets alpha value Value must be positive

Parameters:

value - alpha value

setK

public void setK(double value)

Sets K value (an alias of alpha) Value must be positive

Parameters:

value - alpha value

setBeta

public void setBeta(double value)

Sets beta value Value must be positive

Parameters:

value - alpha value

setLambda

public void setLambda(double value)

Sets lambda value (an alias of (1/beta)) Value must be positive

Parameters:

value - alpha value

getAlpha

public double getAlpha()

Gets the alpha parameter

Returns:

value of alpha

getK

public double getK()

Gets the K parameter (an alias of alpha)

Returns:

value of K

getBeta

public double getBeta()

Gets the beta parameter

Returns:

value of beta

getLambda

public double getLambda()

Gets the lambda parameter (an alias of 1/beta)

Returns:

value of lambda

computeProbability

public double computeProbability(double value)

Computes mass probability at a given point of the gamma distribution.

Specified by:

computeProbability in interface Distribution

Parameters:

value - point selected

Returns:

mass probability at 'value'

computeCumulativeProbability

public double computeCumulativeProbability(double value)

Computes cumulative probability at a given point of the gamma distribution.

Specified by:

computeCumulativeProbability in interface Distribution

Parameters:

value - point selected

Returns:

cumulative probability at 'value'

regularizedGammaP

public double regularizedGammaP(double a,
                                double x)

Computes regularized gamma P function

Parameters:

a - a parameter

x - x value

Returns:

value of the regularized gamma P function

regularizedGammaQ

public double regularizedGammaQ(double a,
                                double x)

Computes regularized gamma Q function

Parameters:

a - a parameter

x - x value

Returns:

value of the regularized gamma Q function

toString

public java.lang.String toString()

To String method.

Overrides:

toString in class java.lang.Object

Returns:

string representation of the distribution