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From "Bill Barker" <billwbar...@verizon.net>
Subject Re: svn commit: r984453 - /commons/proper/math/trunk/src/main/java/org/apache/commons/math/util/MathUtils.java
Date Thu, 12 Aug 2010 01:51:32 GMT


--------------------------------------------------
From: <dimpbx@apache.org>
Sent: Wednesday, August 11, 2010 8:55 AM
To: <commits@commons.apache.org>
Subject: svn commit: r984453 - 
/commons/proper/math/trunk/src/main/java/org/apache/commons/math/util/MathUtils.java

> Author: dimpbx
> Date: Wed Aug 11 15:55:14 2010
> New Revision: 984453
>
> URL: http://svn.apache.org/viewvc?rev=984453&view=rev
> Log:
> MathUtils.safeNorm (translation of enorm.f from Minpack) added
>
> Modified:
> 
> commons/proper/math/trunk/src/main/java/org/apache/commons/math/util/MathUtils.java
>
> Modified: 
> commons/proper/math/trunk/src/main/java/org/apache/commons/math/util/MathUtils.java
> URL: 
> http://svn.apache.org/viewvc/commons/proper/math/trunk/src/main/java/org/apache/commons/math/util/MathUtils.java?rev=984453&r1=984452&r2=984453&view=diff
> ==============================================================================
> ---  
> commons/proper/math/trunk/src/main/java/org/apache/commons/math/util/MathUtils.java 
> (original)
> +++ 
> commons/proper/math/trunk/src/main/java/org/apache/commons/math/util/MathUtils.java 
> Wed Aug 11 15:55:14 2010
> @@ -1955,4 +1955,119 @@ public static void checkOrder(double[] v
>             checkOrder(val, OrderDirection.DECREASING, strict);
>         }
>     }
> +
> + /**
> + * Returns the Cartesian norm (2-norm), handling both overflow and 
> underflow.
> + * Translation of the minpack enorm subroutine.
> + *
> + * The redistribution policy for MINPACK is available <a
> + * href="http://www.netlib.org/minpack/disclaimer">here</a>, for 
> convenience, it
> + * is reproduced below.</p>
> + *
> + * <table border="0" width="80%" cellpadding="10" align="center" 
> bgcolor="#E0E0E0">
> + * <tr><td>
> + *    Minpack Copyright Notice (1999) University of Chicago.
> + *    All rights reserved
> + * </td></tr>
> + * <tr><td>
> + * Redistribution and use in source and binary forms, with or without
> + * modification, are permitted provided that the following conditions
> + * are met:
> + * <ol>
> + *  <li>Redistributions of source code must retain the above copyright
> + *      notice, this list of conditions and the following 
> disclaimer.</li>
> + * <li>Redistributions in binary form must reproduce the above
> + *     copyright notice, this list of conditions and the following
> + *     disclaimer in the documentation and/or other materials provided
> + *     with the distribution.</li>
> + * <li>The end-user documentation included with the redistribution, if 
> any,
> + *     must include the following acknowledgment:
> + *     <code>This product includes software developed by the University 
> of
> + *           Chicago, as Operator of Argonne National Laboratory.</code>
> + *     Alternately, this acknowledgment may appear in the software 
> itself,
> + *     if and wherever such third-party acknowledgments normally 
> appear.</li>
> + * <li><strong>WARRANTY DISCLAIMER. THE SOFTWARE IS SUPPLIED "AS IS"
> + *     WITHOUT WARRANTY OF ANY KIND. THE COPYRIGHT HOLDER, THE
> + *     UNITED STATES, THE UNITED STATES DEPARTMENT OF ENERGY, AND
> + *     THEIR EMPLOYEES: (1) DISCLAIM ANY WARRANTIES, EXPRESS OR
> + *     IMPLIED, INCLUDING BUT NOT LIMITED TO ANY IMPLIED WARRANTIES
> + *     OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, TITLE
> + *     OR NON-INFRINGEMENT, (2) DO NOT ASSUME ANY LEGAL LIABILITY
> + *     OR RESPONSIBILITY FOR THE ACCURACY, COMPLETENESS, OR
> + *     USEFULNESS OF THE SOFTWARE, (3) DO NOT REPRESENT THAT USE OF
> + *     THE SOFTWARE WOULD NOT INFRINGE PRIVATELY OWNED RIGHTS, (4)
> + *     DO NOT WARRANT THAT THE SOFTWARE WILL FUNCTION
> + *     UNINTERRUPTED, THAT IT IS ERROR-FREE OR THAT ANY ERRORS WILL
> + *     BE CORRECTED.</strong></li>
> + * <li><strong>LIMITATION OF LIABILITY. IN NO EVENT WILL THE COPYRIGHT
> + *     HOLDER, THE UNITED STATES, THE UNITED STATES DEPARTMENT OF
> + *     ENERGY, OR THEIR EMPLOYEES: BE LIABLE FOR ANY INDIRECT,
> + *     INCIDENTAL, CONSEQUENTIAL, SPECIAL OR PUNITIVE DAMAGES OF
> + *     ANY KIND OR NATURE, INCLUDING BUT NOT LIMITED TO LOSS OF
> + *     PROFITS OR LOSS OF DATA, FOR ANY REASON WHATSOEVER, WHETHER
> + *     SUCH LIABILITY IS ASSERTED ON THE BASIS OF CONTRACT, TORT
> + *     (INCLUDING NEGLIGENCE OR STRICT LIABILITY), OR OTHERWISE,
> + *     EVEN IF ANY OF SAID PARTIES HAS BEEN WARNED OF THE
> + *     POSSIBILITY OF SUCH LOSS OR DAMAGES.</strong></li>
> + * <ol></td></tr>
> + * </table>
> + *

The NOTICE.txt file should be updated to reflect this.  Since we already 
include the text above in LICENSE.txt, I'm -0 on repeating it here.

> + * @param v vector of doubles
> + * @return the 2-norm of the vector
> + */
> + public static double safeNorm(double[] v) {
> +    double rdwarf = 3.834e-20;
> +    double rgiant = 1.304e+19;
> +    double s1=0.0;
> +    double s2=0.0;
> +    double s3=0.0;
> +    double x1max = 0.0;
> +    double x3max = 0.0;
> +    double floatn = (double)v.length;
> +    double agiant = rgiant/floatn;
> +    for (int i=0;i<v.length;i++) {
> +        double xabs = Math.abs(v[i]);
> +        if (xabs<rdwarf || xabs>agiant) {
> +            if (xabs>rdwarf) {
> +                if (xabs>x1max) {
> +                    double r=x1max/xabs;
> +                    s1=1.0+s1*r*r;
> +                    x1max=xabs;
> +                } else {
> +                    double r=xabs/x1max;
> +                    s1+=r*r;
> +                }
> +            } else {
> +                if (xabs>x3max) {
> +                 double r=x3max/xabs;
> +                 s3=1.0+s3*r*r;
> +                 x3max=xabs;
> +                } else {
> +                    if (xabs!=0.0) {
> +                        double r=xabs/x3max;
> +                        s3+=r*r;
> +                    }
> +                }
> +            }
> +        } else {
> +         s2+=xabs*xabs;
> +        }
> +    }
> +    double norm;
> +    if (s1!=0.0) {
> +        norm = x1max*Math.sqrt(s1+(s2/x1max)/x1max);
> +    } else {

It makes the code more readable if you do:
        if(condition) {
        } else if(other condition) {
        } else {
        }

  Since it isn't in checkstyle, I'm guessing that there is no official 
policy on this.  So this is just my opinion.

> +        if (s2==0.0) {
> +            norm = x3max*Math.sqrt(s3);
> +        } else {
> +            if (s2>=x3max) {
> +                norm = Math.sqrt(s2*(1.0+(x3max/s2)*(x3max*s3)));
> +            } else {
> +                norm = Math.sqrt(x3max*((s2/x3max)+(x3max*s3)));
> +            }
> +        }
> +    }
> +    return norm;
> +}
> +
> }
>
> 

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