GammaFunction (Terrier Information Retrieval Platform 4.1 API)

All Implemented Interfaces:

Serializable
```
public abstract class GammaFunction
extends Object
implements Serializable
```
Base class for implementations of the Gamma function. Use getGammaFunction() to obtain an instance. The exact instance can be controlled by property gamma.function For consistency when computing logarithms of the gamma function, all implementations assume positive input values. In practice, as the gamma function can generate large values, normal usage should use compute_log() anyway.
Properties:
<ul>
gamma.function - class name of the Gamma function implementation. Defaults to use WikipediaLanczosGammaFunction

Constructors
Constructor and Description
`GammaFunction()`

Methods
Modifier and Type	Method and Description
`abstract double`	`compute_log(double number)` Get the value of the log of gamma function for the specified number.
`abstract double`	`compute(double number)` Get the value of the gamma function for the specified number.
`static long`	`factorial(long n)` Compute factorial of n, for 0 < n < 21.
`static GammaFunction`	`getGammaFunction()` Obtain an instance of GammaFunction
`static void`	`main(String[] args)`

Class GammaFunction