Package edu.cnm.deepdive

Class Factorials

java.lang.Object

edu.cnm.deepdive.Factorials

public final class Factorials
extends Object

Implements recursive and iterative forms of factorial computation, returning long and BigInteger results. (When n > 20, n! exceeds the range of values that can be represented by the long type.)

Note that for large values of n, the computation of n! is best done by methods other than those included here.

Method Summary

Modifier and Type	Method	Description
static BigInteger	bigIterative(int n)	Computes (recursively) and returns the factorial of n as a BigInteger.
static BigInteger	bigRecursive(int n)	Computes (recursively) and returns the factorial of n as a BigInteger.
static long	longIterative(int n)	Computes (iteratively) and returns n! as a long.
static long	longRecursive(int n)	Computes (recursively) and returns n! as a long.

Methods inherited from class java.lang.Object

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

Method Details

longRecursive

public static long longRecursive(int n)
                          throws IllegalArgumentException

Computes (recursively) and returns n! as a long. However, if (n > 20), the result overflows the range of long, and is meaningless.

Parameters:

n - Value for which factorial is computed.

Returns:

Factorial of n; that is, n!.

Throws:

IllegalArgumentException - If (n < 0) or (n > 20).

longIterative

public static long longIterative(int n)
                          throws IllegalArgumentException

Computes (iteratively) and returns n! as a long. However, if (n > 20), the result overflows the range of long, and is meaningless.

Parameters:

n - Value for which factorial is computed.

Returns:

Factorial of n; that is, n!.

Throws:

IllegalArgumentException - If (n < 0) or (n > 20).

bigRecursive

public static BigInteger bigRecursive(int n)
                               throws IllegalArgumentException

Computes (recursively) and returns the factorial of n as a BigInteger.

Parameters:

n - Value for which factorial is computed.

Returns:

Factorial of n; that is, n!.

Throws:

IllegalArgumentException - If (n < 0).

bigIterative

public static BigInteger bigIterative(int n)
                               throws IllegalArgumentException

Computes (recursively) and returns the factorial of n as a BigInteger.

Parameters:

n - Value for which factorial is computed.

Returns:

Factorial of n; that is, n!.

Throws:

IllegalArgumentException - If (n < 0).