Re: Motion to finalise interval literals
Bill Walster replied to my question about Sun's meaning of [X]:
> Thanks for your query. I cannot find "degenerate mathematical interval"
> anywhere in the Interval Programming Reference manual. Please point me
> to the place you find unclear.
It came from John Pryce's post:
| From: John Pryce <j.d.pryce@xxxxxxxxxx>
| To: stds-1788 <stds-1788@xxxxxxxxxxxxxxxxx>
| Date: Wed, 5 Jun 2013 00:19:22 +0100
| Subject: Re: P1788: Motion 44 NO votes
| Message-ID: <214ECC9C-1B5D-468A-9865-8451D956B2D7@xxxxxxxxxx>
| References: <F43AD242-B81D-486C-BBE1-415D84D6CA91@xxxxxxxxxxxxx>
|
| ...
| 3.
| Bill Walster's query, May 30. This doesn't point out errors but does
| raise questions about our syntax for literals.
| > I am unable (perhaps it is me) to determine if the scheme implemented
| > in Sun's implementation of string to interval and interval to string
| > conversion will be standard conforming or not.
| ...
| > There are three displayable forms of an external interval:
| > (a) [Xinf, Xsup] represents the mathematical interval [Xinf, Xsup]
| > (b) [X] represents the degenerate mathematical interval [X, X]
| > (c) X represents the non-degenerate mathematical interval [x] + [-1,+1]uld
where I assumed he was quoting from the Sun reference.
I have now peeked at Sun's f95 Interval Reference. Section 2.9.2 is pretty
clear, but John *did* quote text, from 2.10.2.1 -- External Representations.
Section 2.10.2.2 -- Input -- then describes how such a singleton is converted
to an internal representation, by rounding down and up.
So all is clear now. The "external representation" is what corresponds to
our Level 1, the internal representations (for each KIND) are our Level 2.
Michel.
---Sent: 2013-06-06 13:56:53 UTC