Baker, P1788
Chair, are we ready to vote?
I apologise for having written about this motion "Here is text to vote
on", or similar. Well, yes, but motion 46 is not about the actual
wording but about the content. (BTW that means it passes on simple
majority, not two thirds.)
This is important because the motion is in danger of being endlessly
bogged down in the debate
"Do we want a small, basic standard or a larger, fuller-featured
standard?"
As it relates to motion 46:
- Do we want rational number literals such as "22/7"? NO!! (e.g.
Jürgen) YES!! (e.g. Dmitry)
- Do we want other number literals to follow (a) the syntax of the
host language,
or (b) a minimal syntax whose productions are common to all widely
used languages?
[I started with (b), which was criticised; changed to (a);
now there is pressure to go back to (b).]
- etc.
It seems clear we need both a "full" standard, and a "basic" one that
is a subset.
We have a willing candidate to be "Technical Editor for the Basic
Standard" (TEBS) and I hope we can shortly announce he has accepted
the chair's formal invitation. His role is to create the basic subset
and, I hope, a simplified document that describes only that subset.
The basic standard will be angled toward ease of implementation.
That being so, I ask us to vote on motion 46 concentrating on the
principles. Please ignore issues of what details are in or out of the
subset: you will have your say on these when the TEBS makes his
proposals.
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Motion 46, revision of 13 July 2013.
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The syntax and semantics of interval literals shall be as specified in
the attached extract from Draft 7.3.
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Clarification
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- The TEBS will choose a subset to form the definition of interval
literals in the basic standard. ("Subset" means any literal that
conforms to the basic standard also conforms to the full standard.)
- The main principles you are voting on, as I see it, are:
1. Interval literals (ILs) have a mathematical value. Converting
them to finite precision intervals is a separate operation.
2. ILs are what the Level 2 constructor text2interval(), of any
finite precision type, takes as input.
3. ILs have a close relation to interval I/O: it shall be possible
to write an internal interval to an IL, and read an IL to an
internal interval, preserving containment in either direction.
(Not directly covered by this motion, but relevant.)
4. Inf-sup form "[1.2,3.4]" and uncertain form "12.345?6" are both
a Good Thing.
- Whether number literals follow the host language syntax or a simple
language-independent syntax, is left to the TEBS to decide.
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Notes
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- In the new text I have added a definition of what "last place" (an
integer) and "unit in last place" (ulp) mean in this context, since I
learned they have more than one meaning and are unfamiliar to some.
[Example. For the decimal strings 123 and 123. , as well as 0 and 0. ,
the last place is 0 and one ulp is 1. For .123 and 0.123 , as well as
.000 and 0.000 , the last place is −3 and one ulp is 0.001.]
- I hope to have corrected an error in the definition of "exponent
field" for uncertain form, which was inconsistent as to whether the
prefix character 'e' was included or not.
- This was the original version of the motion.
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Motion
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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.