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Class weka.core.SpecialFunctions 

java.lang.Object
   |
   +----weka.core.SpecialFunctions
public final class SpecialFunctions
extends Object
Class implementing some mathematical functions.

Version:
$Revision: 1.2 $
Author:
Eibe Frank (eibe@cs.waikato.ac.nz)

Constructor Index

o SpecialFunctions()

Method Index

o lnFactorial(double)
Returns natural logarithm of factorial using gamma function.
o lnGamma(double)
Returns natural logarithm of gamma function.
o log2Binomial(double, double)
Returns base 2 logarithm of binomial coefficient using gamma function.
o log2Multinomial(double, double[])
Returns base 2 logarithm of multinomial using gamma function.
o main(String[])
Main method for testing this class.

Constructors

o SpecialFunctions 
 public SpecialFunctions()

Methods

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

Parameters:
x - the value
Returns:
natural logarithm of factorial
o lnGamma 
 public static double lnGamma(double x)
Returns natural logarithm of gamma function. Converted to java from Numerical Recipes in C.

Parameters:
x - the value
Returns:
natural logarithm of gamma function
o log2Binomial 
 public static double log2Binomial(double a,
                                   double b) throws ArithmeticException
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
o log2Multinomial 
 public static double log2Multinomial(double a,
                                      double bs[]) throws ArithmeticException
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
o main 
 public static void main(String ops[])
Main method for testing this class. 

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