Package org.apache.commons.numbers.combinatorics

Class Factorial

java.lang.Object

org.apache.commons.numbers.combinatorics.Factorial

public final class Factorial
extends Object

Factorial of a number.

Method Summary

Modifier and Type	Method	Description
static double	doubleValue(int n)	Computes the factorial of n.
static long	value(int n)	Computes the factorial of n.

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)

Computes the factorial of n.

Parameters:

n - Argument.

Returns:

n!

Throws:

IllegalArgumentException - if n < 0.

IllegalArgumentException - if n > 20 (the factorial value is too large to fit in a long).

doubleValue

public static double doubleValue(int n)

Computes the factorial of n.

The result should be small enough to fit into a double: The largest n for which n! does not exceed Double.MAX_VALUE is 170. Double.POSITIVE_INFINITY is returned for n > 170.

Parameters:

n - Argument.

Returns:

n!

Throws:

IllegalArgumentException - if n < 0.

Since:

1.1