net.sf.doodleproject.numerics4j.special
Class Gamma

java.lang.Object
  net.sf.doodleproject.numerics4j.special.Gamma

public final class Gamma
extends java.lang.Object

Utility class that provides methods related to the gamma family of functions.

Version:

$Revision: 1.2 $ $Date: 2007/10/25 04:44:14 $

Method Summary

static double	logGamma(double x) Returns the natural logarithm of the gamma function Γ(x) (1).
static double	regularizedGammaP(double a, double x) Returns the regularized gamma function P(a, x) (1).
static double	regularizedGammaQ(double a, double x) Returns the regularized gamma function Q(a, x) = 1 - P(a, x) (1).

Methods inherited from class java.lang.Object

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

Method Detail

logGamma

public static double logGamma(double x)

Returns the natural logarithm of the gamma function Γ(x) (1).

References:

1. Eric W. Weisstein. "Gamma Function." From MathWorld--A Wolfram Web Resource. http://mathworld.wolfram.com/GammaFunction.html

Parameters:

x - the point of evaluation.

Returns:

log(Γ(x))

regularizedGammaP

public static double regularizedGammaP(double a,
                                       double x)
                                throws NumericException

Returns the regularized gamma function P(a, x) (1).

References:

1. Eric W. Weisstein. "Regularized Gamma Function." From MathWorld--A Wolfram Web Resource. http://mathworld.wolfram.com/RegularizedGammaFunction.html

Parameters:

x - the evaluation point.

a - the a parameter.

Returns:

P(a, x)

Throws:

NumericException - if the value could not be computed.

regularizedGammaQ

public static double regularizedGammaQ(double a,
                                       double x)
                                throws NumericException

Returns the regularized gamma function Q(a, x) = 1 - P(a, x) (1).

References:

1. Eric W. Weisstein. "Regularized Gamma Function." From MathWorld--A Wolfram Web Resource. http://mathworld.wolfram.com/RegularizedGammaFunction.html

Parameters:

x - the evaluation point.

a - the a parameter.

Returns:

Q(a, x)

Throws:

NumericException - if the value could not be computed.