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RE: [F&O]: Result of arithmetic involving Inf

From: Michael Kay <mhk@mhk.me.uk>
Date: Wed, 28 Jul 2004 10:11:11 +0100
To: "'Ashok Malhotra'" <ashok.malhotra@oracle.com>, "'Henry Zongaro'" <zongaro@ca.ibm.com>, <public-qt-comments@w3.org>
Message-Id: <20040728091204.492EAA18B1@frink.w3.org>

> Henry:
> I believe you are referring to adding, subtracting and 
> multiplying a finite
> number by +/- INF.  In this case, it seems reasonable that 
> the result should be
> +/- INF.  Also, INF + INF = INF and -INF - (-INF) = -INF.
> 
> While these seem reasonable, I come to that conclusion by 
> inference from what
> IEEE-754 does say and not from any direct statement therein.  
> If you were 
> quoting directly from 754 please provide a reference.  I 
> could not find one.
> 
> I suggest we remove statement you objected to and add notes 
> to op:numeric-add/subtract/multiply, covering these cases, 
> similar to the note we added for 
> op:numeric-divide.

We should not try to precis IEEE 754. It might seem helpful to the reader,
but the risk of introducing errors is far too high. Illustrate the effect by
examples, by all means (it's well recognized that these are non-normative),
but don't try to copy selected IEEE 754 statements into the rules.

Michael Kay
Received on Wednesday, 28 July 2004 05:12:04 UTC

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