org.apache.mahout.math.jet.stat

Class Gamma

java.lang.Object

org.apache.mahout.math.jet.stat.Gamma

public final class Gamma
extends Object

Partially deprecated until unit tests are in place. Until this time, this class/interface is unsupported.

Method Summary

Methods

Modifier and Type	Method and Description
static double	beta(double alpha, double beta) Returns the beta function of the arguments.
static double	gamma(double x) Returns the Gamma function of the argument.
static double	incompleteBeta(double alpha, double beta, double xx) Returns the regularized Incomplete Beta Function evaluated from zero to xx; formerly named ibeta.
static double	incompleteGamma(double alpha, double x) Returns the Incomplete Gamma function; formerly named igamma.
static double	incompleteGammaComplement(double alpha, double x) Returns the Complemented Incomplete Gamma function; formerly named igamc.
static double	logGamma(double x) Returns the natural logarithm of the gamma function; formerly named lgamma.

Methods inherited from class java.lang.Object

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

Method Detail

beta

public static double beta(double alpha,
          double beta)

Returns the beta function of the arguments.

                   -     -
                  | (a) | (b)
 beta( a, b )  =  -----------.
                     -
                    | (a+b)
 

Parameters:

alpha -

beta -

Returns:

The beta function for given values of alpha and beta.

gamma

public static double gamma(double x)

Returns the Gamma function of the argument.

incompleteBeta

public static double incompleteBeta(double alpha,
                    double beta,
                    double xx)

Returns the regularized Incomplete Beta Function evaluated from zero to xx; formerly named ibeta. See http://en.wikipedia.org/wiki/Incomplete_beta_function#Incomplete_beta_function

Parameters:

alpha - the alpha parameter of the beta distribution.

beta - the beta parameter of the beta distribution.

xx - the integration end point.

incompleteGamma

public static double incompleteGamma(double alpha,
                     double x)

Returns the Incomplete Gamma function; formerly named igamma.

Parameters:

alpha - the shape parameter of the gamma distribution.

x - the integration end point.

Returns:

The value of the unnormalized incomplete gamma function.

incompleteGammaComplement

public static double incompleteGammaComplement(double alpha,
                               double x)

Returns the Complemented Incomplete Gamma function; formerly named igamc.

Parameters:

alpha - the shape parameter of the gamma distribution.

x - the integration start point.

logGamma

public static double logGamma(double x)

Returns the natural logarithm of the gamma function; formerly named lgamma.