repicea.math

Class GammaFunction

java.lang.Object

repicea.math.GammaFunction

public class GammaFunction
extends java.lang.Object

This class implements the Gamma function.

Constructor Summary

Constructors

Constructor and Description
GammaFunction()

Method Summary

Modifier and Type	Method and Description
static double	gamma(double z) This method returns the result of the Gamma function.
static double	inverseGamma(double z) This method implements the approximation of the inverse Gamma function designed by David W.
static double	logGamma(double z) This method returns the logarithm of the Gamma function.

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

gamma

public static double gamma(double z)

This method returns the result of the Gamma function. The implementation is the Lanczos approximation.

Parameters:

z -

Returns:

a double

logGamma

public static double logGamma(double z)

This method returns the logarithm of the Gamma function.

Parameters:

z -

Returns:

a double

inverseGamma

public static double inverseGamma(double z)

This method implements the approximation of the inverse Gamma function designed by David W. Cantrell (see http://mathforum.org/kb/message.jspa?messageID=342551&tstart=0).

Parameters:

z - a double equal or greater than 1.

Returns:

a double