Re: Motion 46: finalise interval literals, amendments
Michel,
That's a good point. That makes me think it is not
as easy to dismiss the text2interval function.
However, what about this argument: If Ned's
function gives, say, as a lower bound,
the largest floating point number less than
or equal to the value represented by the text
corresponding to the lower bound, won't the
lower bound of the interval hull (what you
called "union") also be the best floating
point lower bound (with a corresponding argument
for the upper bound)?
Baker
----- Original Message -----
From: "Michel Hack" <mhack@xxxxxxx>
To: "stds-1788" <stds-1788@xxxxxxxxxxxxxxxxx>
Sent: Wednesday, June 26, 2013 8:56:16 AM
Subject: Re: Motion 46: finalise interval literals, amendments
Ned Nedialkov wrote:
>> I meant take a string that represents one decimal number, e.g. "0.1".
>> Then text2interval("0.1") will return the binary interval containing 0.1.
>>
>> Then leave to the user to convert left and right bounds. This will make
>> it simpler for the standard and more flexible for the user.
Baker Kearfott replied:
> The user would then rely on the P-1788 floating-point-to-interval
> constructor "nums2interval".
No -- Ned's text2interval() returns an interval enclosing the singleton.
The next step would therefore be the Union operator.
Ned's approach could also be used for midrad input, by first constructing
two intervals imid and irad, and then taking Union(imid-irad,imid+irad).
This approach guarantees enclosure. We should check if there are cases
where the enclosure is not tightest, assuming the primitives do return
a tightest enclosure in the target format.
Michel.
---Sent: 2013-06-26 15:05:11 UTC
--
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Ralph Baker Kearfott, rbk@xxxxxxxxxxxxx (337) 482-5346 (fax)
(337) 482-5270 (work) (337) 993-1827 (home)
URL: http://interval.louisiana.edu/kearfott.html
Department of Mathematics, University of Louisiana at Lafayette
(Room 217 Maxim D. Doucet Hall, 1403 Johnston Street)
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