Java BigInteger Factorial factorial(BigInteger n)

Description

Compute the Factorial of n, often written as c! in mathematics.

License

Open Source License

Parameter

Parameter	Description
n	Note: n &gt;= 0. This BigInteger <code>n</code> will be 0 after this method finishes.

Return

n * (n-1) * (n-2) * ... * 1

Declaration

public static BigInteger factorial(BigInteger n) 

Method Source Code

//package com.java2s;
/*//from ww  w  . ja  va  2s  .  co m
 This file is part of ELKI:
 Environment for Developing KDD-Applications Supported by Index-Structures
    
 Copyright (C) 2015
 Ludwig-Maximilians-Universit?t M?nchen
 Lehr- und Forschungseinheit f?r Datenbanksysteme
 ELKI Development Team
    
 This program is free software: you can redistribute it and/or modify
 it under the terms of the GNU Affero General Public License as published by
 the Free Software Foundation, either version 3 of the License, or
 (at your option) any later version.
    
 This program is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 GNU Affero General Public License for more details.
    
 You should have received a copy of the GNU Affero General Public License
 along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

import java.math.BigInteger;

public class Main {
    /**
     * Compute the Factorial of n, often written as <code>c!</code> in
     * mathematics.
     * <p>
     * Use this method if for large values of <code>n</code>.
     * </p>
     *
     * @param n Note: n &gt;= 0. This {@link BigInteger} <code>n</code> will be 0
     *        after this method finishes.
     * @return n * (n-1) * (n-2) * ... * 1
     */
    public static BigInteger factorial(BigInteger n) {
        BigInteger nFac = BigInteger.ONE;
        while (n.compareTo(BigInteger.ONE) > 0) {
            nFac = nFac.multiply(n);
            n = n.subtract(BigInteger.ONE);
        }
        return nFac;
    }

    /**
     * Compute the Factorial of n, often written as <code>c!</code> in
     * mathematics.
     *
     * @param n Note: n &gt;= 0
     * @return n * (n-1) * (n-2) * ... * 1
     */
    public static long factorial(int n) {
        long nFac = 1;
        for (long i = n; i > 0; i--) {
            nFac *= i;
        }
        return nFac;
    }
}

Related

1. factorial(BigInteger n)
2. factorial(BigInteger number)
3. factorial(BigInteger originValue)