RE: Do I have a second? Re: Motion to finalise interval literals
I tried to say that I second, but my message seems to have bounced back
________________________________________
From: stds-1788@xxxxxxxx [stds-1788@xxxxxxxx] On Behalf Of Ralph Baker Kearfott [rbk@xxxxxxxxxxxxx]
Sent: Wednesday, June 05, 2013 12:54 PM
To: stds-1788
Subject: Do I have a second? Re: Motion to finalise interval literals
P-1788,
Do I have a formal second to this motion?
Baker
On 06/05/2013 04:51 AM, John Pryce wrote:
> P1788
> Though motion 44 passed, there hasn't been IMO sufficient discussion on the form of interval literals. I propose this, to crystallise people's objections if any, get helpful modifications, and hopefully lead to a consensus.
> John Pryce
>
> ======
> Motion
> ======
> The syntax and semantics of interval literals shall be
> - as specified in Draft 7.1 circulated as 20130402Level1and2textV7.1Sent.pdf;
> - with the addition of the singleton interval form [x] which is equivalent to [x,x].
>
> The standard will not at this stage include a facility for named constants such as pi to be included in the definition of an interval literal.
>
> =========
> Rationale
> =========
> People of repute have supported the 3 different forms of number literal and 4 forms of interval literal, so I think they will prove useful in practice. The [x] form is a trivial addition, very common in the literature (and used by the Sun interval languages).
>
> I'm less certain of allowing more than one kind of number literal in one interval literal, e.g.
> <22/7 +- 0x6p-3>
> (encloses \pi, I think). E.g. can parsing problems occur?
>
> I'm also not sure the proposed syntax is locale-proofable. Locale experts please help.
>
> So people looking for nasty examples would be helpful.
>
> The reason for omitting named constants is that when proposed before, people thought "Ah, that means we can have constant expressions as well". If one allows (exact real) pi as an endpoint, say, then surely one needs pi/4? pi/6? But where does one stop? What about 1.23+tan(pi/7)? With only a few operations allowed, one can produce expressions whose sign is incredibly hard to determine, or undecidable I believe.
>
> So any such feature should await a revision of the standard IMO.
>
--
---------------------------------------------------------------
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)
Box 4-1010, Lafayette, LA 70504-1010, USA
---------------------------------------------------------------