Package org.apache.commons.numbers.combinatorics

Class BinomialCoefficient

java.lang.Object

org.apache.commons.numbers.combinatorics.BinomialCoefficient

public final class BinomialCoefficient
extends Object

Representation of the binomial coefficient. It is "n choose k", the number of k-element subsets that can be selected from an n-element set.

Method Summary

Modifier and Type	Method	Description
static long	value(int n, int k)	Computes the binomial coefficient.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Details

value

public static long value(int n,
 int k)

Computes the binomial coefficient.

The largest value of n for which all coefficients can fit into a long is 66. Larger n may result in an ArithmeticException depending on the value of k.

Any min(k, n - k) >= 34 cannot fit into a long and will result in an ArithmeticException.

Parameters:

n - Size of the set.

k - Size of the subsets to be counted.

Returns:

n choose k.

Throws:

IllegalArgumentException - if n < 0, k < 0 or k > n.

ArithmeticException - if the result is too large to be represented by a long.