MathUtil.java Source code

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Here is the source code for MathUtil.java

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/*
 * $RCSfile: MathUtil.java,v $
 * $Revision: 1.1 $
 * $Date: 2005/02/11 05:02:25 $
 * $State: Exp $
 *
 * Class:                   MathUtil
 *
 * Description:             Utility mathematical methods
 *
 *
 *
 * COPYRIGHT:
 *
 * This software module was originally developed by Raphal Grosbois and
 * Diego Santa Cruz (Swiss Federal Institute of Technology-EPFL); Joel
 * Askelf (Ericsson Radio Systems AB); and Bertrand Berthelot, David
 * Bouchard, Flix Henry, Gerard Mozelle and Patrice Onno (Canon Research
 * Centre France S.A) in the course of development of the JPEG2000
 * standard as specified by ISO/IEC 15444 (JPEG 2000 Standard). This
 * software module is an implementation of a part of the JPEG 2000
 * Standard. Swiss Federal Institute of Technology-EPFL, Ericsson Radio
 * Systems AB and Canon Research Centre France S.A (collectively JJ2000
 * Partners) agree not to assert against ISO/IEC and users of the JPEG
 * 2000 Standard (Users) any of their rights under the copyright, not
 * including other intellectual property rights, for this software module
 * with respect to the usage by ISO/IEC and Users of this software module
 * or modifications thereof for use in hardware or software products
 * claiming conformance to the JPEG 2000 Standard. Those intending to use
 * this software module in hardware or software products are advised that
 * their use may infringe existing patents. The original developers of
 * this software module, JJ2000 Partners and ISO/IEC assume no liability
 * for use of this software module or modifications thereof. No license
 * or right to this software module is granted for non JPEG 2000 Standard
 * conforming products. JJ2000 Partners have full right to use this
 * software module for his/her own purpose, assign or donate this
 * software module to any third party and to inhibit third parties from
 * using this software module for non JPEG 2000 Standard conforming
 * products. This copyright notice must be included in all copies or
 * derivative works of this software module.
 *
 * Copyright (c) 1999/2000 JJ2000 Partners.
 * */

/**
 * This class contains a collection of utility methods fro mathematical
 * operations. All methods are static.
 * */
public class MathUtil {
    /** 
     * Method that calculates the Least Common Multiple (LCM) of two strictly
     * positive integer numbers.
     *
     * @param x1 First number
     *
     * @param x2 Second number
     * */
    public static final int lcm(int x1, int x2) {
        if (x1 <= 0 || x2 <= 0) {
            throw new IllegalArgumentException("Cannot compute the least " + "common multiple of two "
                    + "numbers if one, at least," + "is negative.");
        }
        int max, min;
        if (x1 > x2) {
            max = x1;
            min = x2;
        } else {
            max = x2;
            min = x1;
        }
        for (int i = 1; i <= min; i++) {
            if ((max * i) % min == 0) {
                return i * max;
            }
        }
        throw new Error("Cannot find the least common multiple of numbers " + x1 + " and " + x2);
    }

    /** 
     * Method that calculates the Least Common Multiple (LCM) of several
     * positive integer numbers.
     *
     * @param x Array containing the numbers.
     * */
    public static final int lcm(int[] x) {
        if (x.length < 2) {
            throw new Error("Do not use this method if there are less than" + " two numbers.");
        }
        int tmp = lcm(x[x.length - 1], x[x.length - 2]);
        for (int i = x.length - 3; i >= 0; i--) {
            if (x[i] <= 0) {
                throw new IllegalArgumentException("Cannot compute the least " + "common multiple of "
                        + "several numbers where " + "one, at least," + "is negative.");
            }
            tmp = lcm(tmp, x[i]);
        }
        return tmp;
    }

}