weka.core
Class SpecialFunctions

java.lang.Object
  extended by weka.core.SpecialFunctions
All Implemented Interfaces:
RevisionHandler

public final class SpecialFunctions
extends java.lang.Object
implements RevisionHandler

Class implementing some mathematical functions.

Version:
$Revision: 1.8 $
Author:
Eibe Frank (eibe@cs.waikato.ac.nz)

Constructor Summary
SpecialFunctions()
           
 
Method Summary
 java.lang.String getRevision()
          Returns the revision string.
static double lnFactorial(double x)
          Returns natural logarithm of factorial using gamma function.
static double log2Binomial(double a, double b)
          Returns base 2 logarithm of binomial coefficient using gamma function.
static double log2Multinomial(double a, double[] bs)
          Returns base 2 logarithm of multinomial using gamma function.
static void main(java.lang.String[] ops)
          Main method for testing this class.
 
Methods inherited from class java.lang.Object
equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

SpecialFunctions

public SpecialFunctions()
Method Detail

lnFactorial

public static double lnFactorial(double x)
Returns natural logarithm of factorial using gamma function.

Parameters:
x - the value
Returns:
natural logarithm of factorial

log2Binomial

public static double log2Binomial(double a,
                                  double b)
Returns base 2 logarithm of binomial coefficient using gamma function.

Parameters:
a - upper part of binomial coefficient
b - lower part
Returns:
the base 2 logarithm of the binominal coefficient a over b

log2Multinomial

public static double log2Multinomial(double a,
                                     double[] bs)
Returns base 2 logarithm of multinomial using gamma function.

Parameters:
a - upper part of multinomial coefficient
bs - lower part
Returns:
multinomial coefficient of a over the bs

getRevision

public java.lang.String getRevision()
Returns the revision string.

Specified by:
getRevision in interface RevisionHandler
Returns:
the revision

main

public static void main(java.lang.String[] ops)
Main method for testing this class.