jebl.math
Class GammaFunction

java.lang.Object
  jebl.math.GammaFunction

public class GammaFunction
extends Object

gamma function

Author:

Korbinian Strimmer

Constructor Summary

GammaFunction()

Method Summary

static double	incompleteGammaP(double a, double x) Incomplete Gamma function P(a,x) = 1-Q(a,x) (a cleanroom implementation of Numerical Recipes gammp(a,x); in Mathematica this function is 1-GammaRegularized)
static double	incompleteGammaP(double a, double x, double lnGammaA) Incomplete Gamma function P(a,x) = 1-Q(a,x) (a cleanroom implementation of Numerical Recipes gammp(a,x); in Mathematica this function is 1-GammaRegularized)
static double	incompleteGammaQ(double a, double x) Incomplete Gamma function Q(a,x) (a cleanroom implementation of Numerical Recipes gammq(a,x); in Mathematica this function is called GammaRegularized)
static double	lnGamma(double alpha) log Gamma function: ln(gamma(alpha)) for alpha>0, accurate to 10 decimal places

Methods inherited from class java.lang.Object

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

Constructor Detail

GammaFunction

public GammaFunction()

Method Detail

lnGamma

public static double lnGamma(double alpha)

log Gamma function: ln(gamma(alpha)) for alpha>0, accurate to 10 decimal places

Parameters:

alpha - argument

incompleteGammaQ

public static double incompleteGammaQ(double a,
                                      double x)

Incomplete Gamma function Q(a,x) (a cleanroom implementation of Numerical Recipes gammq(a,x); in Mathematica this function is called GammaRegularized)

Parameters:

a - parameter

x - argument

Returns:

function value

incompleteGammaP

public static double incompleteGammaP(double a,
                                      double x)

Incomplete Gamma function P(a,x) = 1-Q(a,x) (a cleanroom implementation of Numerical Recipes gammp(a,x); in Mathematica this function is 1-GammaRegularized)

Parameters:

a - parameter

x - argument

Returns:

function value

incompleteGammaP

public static double incompleteGammaP(double a,
                                      double x,
                                      double lnGammaA)

Incomplete Gamma function P(a,x) = 1-Q(a,x) (a cleanroom implementation of Numerical Recipes gammp(a,x); in Mathematica this function is 1-GammaRegularized)

Parameters:

a - parameter

x - argument

lnGammaA - precomputed lnGamma(a)

Returns:

function value