dev.nm.number.big

Class BigIntegerUtils

java.lang.Object

dev.nm.number.big.BigIntegerUtils

public final class BigIntegerUtils
extends Object

These are the utility functions to manipulate BigInteger.

See Also:

Class BigInteger

Method Summary

Modifier and Type	Method and Description
static BigInteger	combination(int n, int k) Compute the combination function or the binomial coefficient.
static BigInteger	factorial(int n) Compute the n factorial.
static BigInteger	permutation(int n, int k) Compute the permutation function.

Methods inherited from class java.lang.Object

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

Method Detail

factorial

public static BigInteger factorial(int n)

Compute the n factorial.

Parameters:

n - an integer

Returns:

n!

See Also:

Wikipedia: Factorial

combination

public static BigInteger combination(int n,
                                     int k)

Compute the combination function or the binomial coefficient. It is the number of k-combinations (each of size k) from a set k with n elements (size n).

Parameters:

n - the size of the full set

k - the size of a combination

Returns:

n! / (n-k)! / k!

See Also:

Wikipedia: Combination

permutation

public static BigInteger permutation(int n,
                                     int k)

Compute the permutation function. It is the number of k-permutations (each of size k) from a set k with n elements (size n).

Parameters:

n - the size of the full set

k - the size of a permutation

Returns:

n! / (n-k)!

See Also:

Wikipedia: Permutation