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Re: Canonical representation of -0.0

From: Arjohn Kampman <arjohn.kampman@aduna.biz>
Date: 15 Oct 2003 15:30:27 +0200
Message-ID: <3F8CF27C.4010607@aduna.biz>
To: Xan Gregg <xan.gregg@jmp.com>
Cc: www-xml-schema-comments@w3.org




Xan Gregg wrote:

>> Reading through the definition of the datatype 'decimal' and working
>> on an algorithm that normalizes these, I came across an exotic case that
>> might not be correctly normalized when the specs are followed. This case
>> is the decimal -0.0. If I understand the specs correctly, the canonical
>> form of this decimal is again -0.0, but I would expect it to be 0.0. I
>> scanned through the errate but couldn't find anything that's related to
>> this. Can someone tell me if this is an error in the XML Schema
>> datatypes specs?
> 
> 
> Looks like an error in the description of canonical represention.  The 
> canonicl represention is defined by prohibiting certain lexical 
> representation, but "-0.0" is not prohibited, as you've observed. 
> However, there is no negative zero in the value space of decimal, so 
> "-0.0" presumably represents the same value as "0.0" (but, by 
> definition, only one of them can be the canonical representation).  Or 
> perhaps it is an error that "-0.0" is a valid lexical representation at 
> all.

Thanks for the feedback. I have made my algorithm such that it
normalizes "-0.0" to "0.0". I saw that similar behaviour is specified
for floats and doubles, so this looks like the most sensible thing to
do.

Thanks again,

Arjohn Kampman

-- 
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Received on Wednesday, 15 October 2003 09:32:01 UTC

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