math.cern

Class BetaFun

java.lang.Object

math.cern.BetaFun

public final class BetaFun
extends Object

This is a utility class that provides computation methods related to the Beta family of functions.

Implementation:

Some code taken and adapted from the Java 2D Graph Package 2.4, which in turn is a port from the Cephes 2.2 Math Library (C). Most Cephes code (missing from the 2D Graph Package) directly ported.

Author:

wolfgang.hoschek@cern.ch

Method Summary

Modifier and Type	Method and Description
static double	beta(double alpha, double beta) Returns the Beta function of the arguments.
static double	incompleteBeta(double alpha, double beta, double x) Returns the Incomplete Beta Function evaluated from zero to x.
static double	lnBeta(double alpha, double beta) Returns the natural logarithm of the beta function.

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.

                          -         -
                         | (alpha) | (beta)
 Beta( alpha, beta )  =  ------------------.
                            -
                           | (alpha+beta)
 

Parameters:

alpha - the alpha parameter

beta - the beta parameter

Returns:

the value of the beta function

lnBeta

public static double lnBeta(double alpha,
                            double beta)

Returns the natural logarithm of the beta function.

Parameters:

alpha - the alpha parameter

beta - the beta parameter

Returns:

the value of the natural log of the beta function

incompleteBeta

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

Returns the Incomplete Beta Function evaluated from zero to x.

Parameters:

alpha - the alpha parameter of the beta distribution.

beta - the beta parameter of the beta distribution.

x - the integration end point.

Returns:

the value of the incomplete beta function