org.apache.mahout.math.jet.math
Class Arithmetic

java.lang.Object
  extended by org.apache.mahout.math.jet.math.Arithmetic

public final class Arithmetic
extends Object

Arithmetic functions.


Method Summary
static double binomial(long n, long k)
          Efficiently returns the binomial coefficient, often also referred to as "n over k" or "n choose k".
static double logFactorial(int k)
          Returns log(k!).
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Method Detail

binomial

public static double binomial(long n,
                              long k)
Efficiently returns the binomial coefficient, often also referred to as "n over k" or "n choose k". The binomial coefficient is defined as

Returns:
the binomial coefficient.

logFactorial

public static double logFactorial(int k)
Returns log(k!). Tries to avoid overflows. For k<30 simply looks up a table in O(1). For k>=30 uses stirlings approximation.

Parameters:
k - must hold k >= 0.


Copyright © 2008–2014 The Apache Software Foundation. All rights reserved.