Safely calculate hypotenuse value. - Java java.lang

Java examples for java.lang:Math Operation

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Description

Safely calculate hypotenuse value.

Demo Code

/**   Basic numeric operations not included in standard Java run-time library.
 *
 *   <p>/* w w  w.  jav a  2s  .  c o m*/
 *   The binomial methods are modified from those in the Colt library.
 *   </p>
 *
 *   <p>
 *   The following methods for trigonometric functions come from the
 *   Sfun class written by Visual Numerics.
 *   </p>
 *
 *   <ul>
 *   <li>acosh</li>
 *   <li>asinh</li>
 *   <li>atanh</li>
 *   <li>cot</li>
 *   <li>cosh</li>
 *   <li>sinh</li>
 *   <li>tanh</li>
 *   </ul>
 *
 *   <p>
 *   These methods are covered by the following license.
 *   </p>
 *
 * -------------------------------------------------------------------------
 *   $Id: Sfun.java,v 1.1.1.1 1999/03/05 21:43:39 brophy Exp $
 * -------------------------------------------------------------------------
 * Copyright (c) 1997 - 1998 by Visual Numerics, Inc. All rights reserved.
 *
 * Permission to use, copy, modify, and distribute this software is freely
 * granted by Visual Numerics, Inc., provided that the copyright notice
 * above and the following warranty disclaimer are preserved in human
 * readable form.
 *
 * Because this software is licensed free of charge, it is provided
 * "AS IS", with NO WARRANTY.  TO THE EXTENT PERMITTED BY LAW, VNI
 * DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
 * TO ITS PERFORMANCE, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 * VNI WILL NOT BE LIABLE FOR ANY DAMAGES WHATSOEVER ARISING OUT OF THE USE
 * OF OR INABILITY TO USE THIS SOFTWARE, INCLUDING BUT NOT LIMITED TO DIRECT,
 * INDIRECT, SPECIAL, CONSEQUENTIAL, PUNITIVE, AND EXEMPLARY DAMAGES, EVEN
 * IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
 *
 * -------------------------------------------------------------------------
 */
//package com.java2s;

public class Main {
    public static void main(String[] argv) throws Exception {
        double a = 2.45678;
        double b = 2.45678;
        System.out.println(hypot(a, b));
    }

    /**   Safely calculate hypotenuse value.
     *
     *   @param   a   One leg of triangle.
     *   @param   b   Second leg of triangle.
     *
     *   @return      Hypotenuse value.
     *
     *   <p>
     *   The hypotenuse value is given mathematically as
     *   the sqrt( a^2 + b^2 ).  The method implemented
     *   here reduces the chances of cancellation and
     *   roundoff error.  If the |a| > |b|, we compute
     *   the hypotenuse as:
     *   </p>
     *
     *   <p>
     *  hypotenuse   = |a| * sqrt( 1 + (b/a) * (b/a) )
     *   </p>
     *
     *   <p>
     *   Otherwise b != 0 compute the hypotenuse as:
     *   </p>
     *
     *   <p>
     *  hypotenuse   = |b| * sqrt( 1 + (a/b) * (a/b) )
     *   </p>
     *
     *   <p>
     *   If b is zero, the hypotenuse is zero.
     *   </p>
     */

    public static double hypot(double a, double b) {
        double r;

        if (Math.abs(a) > Math.abs(b)) {
            r = b / a;
            r = Math.abs(a) * Math.sqrt(1.0D + r * r);
        } else if (b != 0) {
            r = a / b;
            r = Math.abs(b) * Math.sqrt(1.0D + r * r);
        } else {
            r = 0.0D;
        }

        return r;
    }
}

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