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Re: Candidate Recommendation

From: Andrew Robbins <andjrob@gmail.com>
Date: Wed, 16 Dec 2009 04:30:13 -0500
Message-ID: <4B28A8A5.9000600@gmail.com>
To: David Carlisle <davidc@nag.co.uk>
CC: www-math@w3.org
Before MathML3 becomes a true Recommendation, I thought I should point 
out that the example given in 4.2.1.2 "Strict uses of <cn>" for the 
"hexdouble" datatype mentions that this holds 64 bits and 16 hexdigits 
(which is correct), but the example uses 8 hexdigits (which is incorrect).

On the same subject, I was wondering why the "hexdouble" was created 
(since the type did not exist in MathML2), and whether it would be more 
economical to reference C99, and use its hexidecimal notation for 
floats. A nice page descriping C99 hex doubles can be found at 
<http://www.gnu.org/software/libc/manual/html_node/Parsing-of-Floats.html>. 
Using this notation, a hex double could be encoded with the "double" 
type, so the "hexdouble" type wouldn't be needed at all, and <cn> would 
be easier to implement in C99 (with strtod), obviously. The reason the 
"99" is important is that C89 did not have a notation for NaNs, but C99 
does have a notation for NaNs, so there is a one-to-one mapping between 
C99 hex double notation and the binary form.

Regards,

Andrew Robbins
Received on Thursday, 17 December 2009 11:21:11 GMT

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