Re: -0 and +0
Vincent,
On 04/25/2013 08:08 AM, Vincent Lefevre wrote:
On 2013-04-25 05:50:08 -0500, Ralph Baker Kearfott wrote:
At this point, I will need to review all of our motions; perhaps
someone can help remind me. I vaguely recall we decided we would
have only one 0, and not -0 and +0 in the standard. (Of course,
this would not mean implementers could not use this 754 feature
in implementing 1788.)
This is a bit meaningless: What does "have only one 0" mean? At
which level? ...
I think John summarized it well: We're considering only
CLOSED intervals, and how do we interpret -0 and +0
in that context? In any case, I am beginning to
regret bringing up the issue, which may be a bit
of a red herring, in the first place. I thought I was
merely commenting on an innocuous issue of notation.
AFAIK, the main point that was decided about this is Motion 3,
which says:
The P1788 Interval arithmetic standard defines intervals as
closed and connected sets of real numbers.
That means that ±Infinity may be used to denote an unbounded
interval but are never considered as members of an interval.
YES!
This is at Level 1 and Level 2. Representation (Level 3) is another
matter, where you can't ignore that a number format may have signed
zeros...
and we may possibly not specify that much at level 3. Isn't
level 3 still up in the air, anyway?
Best regards,
Baker
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Ralph Baker Kearfott, rbk@xxxxxxxxxxxxx (337) 482-5346 (fax)
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URL: http://interval.louisiana.edu/kearfott.html
Department of Mathematics, University of Louisiana at Lafayette
(Room 217 Maxim D. Doucet Hall, 1403 Johnston Street)
Box 4-1010, Lafayette, LA 70504-1010, USA
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