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Re: Fwd: Motion 44.01 PLEASE VOTE - I vote No

Thanks, Baker.
Well, the interval standard needs to give users a way to specify exactly to WHAT interval a given string is converted.
This is exactly what is done in Sun's Fortran string input conversion and interval output conversion. Thus, it is possible to specify that the interval [0.1, 0.1] is to be interpreted as the infinite precision real number equal to 1/10, or as the exact real interval [0,2/10].
Other features include the ability to enter 0.1000 and to have this automatically converted to [0.0999, 0.1001].
It is these kinds of details that contribute to ease of use and reliability than I believe should be permitted by the standard. This is why I also believe in general that the standard should not be prescriptive, but rather should be permissive, provided only that containment is never violated, both on conversion from and to strings, which includes I/O.
By your qustion "Is text2interval([.1,.1]) unique? do you mean the result of text2interval (.), then I believe the answer should be NO and there needs to be a way to specify more details about the conversion process, as described above and in the Fortran Reference Manual, which I believe people might benefit from reading in its entirety. The same goes for the conversion interval2text(.). 

See: <http://docs.oracle.com/cd/E19059-01/stud.10/819-0503/819-0503.pdf>

Cheers,

Bill



On 5/31/13 2:27 AM, Ralph Baker Kearfott wrote:

Bill, P-1788,

Indeed, 9.6.8 does not specify exactly to WHAT interval the
string is converted, but refers to clause 13.  It is made
specific in 13.2 (specification for "text2interval"), and we
haven't formally processed the actual text of 13.2 yet.  My
reading of 13.2 is that, in general, the only requirement
is that text2interval return an enclosure for the human-understood
number or interval represented by "s", but that for an interval
type based on the 754 format, it should return the tightest
such enclosure.  My reading of this is that, if the Sun F95
interval implementation does not claim to be based on IEEE 754,
it is conforming as long as it returns an interval containing
the result, but, if it claims to be a 754-conforming type,
it must return the tightest such interval.

For example,
for a non-754 conforming type, text2interval([.5,.5]) could store
the binary representation (or other internal representation) of [.5,.5]
or it could store its internal representation corresponding
to [.4,.6]. For a 754-conforming type, text2interval([.5,.5]) must return 
an internal representation of the point interval [.5,.5], but
text2interval([.1,.1]) would need to return a non-zero-width
interval that must be the narrowest such interval containing [.1,.1].

Please correct me if I am wrong.

Shall we put some non-normative examples in clause 13?

Hopefully we can process clause 13 soon.

A question:  Is text2interval([.1,.1]) unique?
             (This would be important for reproducibility.)

Best regards,

Baker

P.S. Bill, I have added your name to the p-1788 list, so it should
     accept email from you.

On 05/30/2013 09:14 PM, Corliss, George wrote:



Begin forwarded message:
*From: *"G. William (Bill) Walster" <bill@xxxxxxxxxxx <mailto:bill@xxxxxxxxxxx>> 
*Subject: **Re: Motion 44.01 PLEASE VOTE - I vote No*
*Date: *May 30, 2013 6:29:08 PM CDT
*Cc: *"Corliss, George" <george.corliss@xxxxxxxxxxxxx <mailto:george.corliss@xxxxxxxxxxxxx>> 

George,
I am unable to send the following to the P1788 email address <stds-1788@xxxxxxxxxxxxxxxxx> that I have. So, will you please forward it to the alias for me? 

Thanks in advance,

Bill

=====email to P1788=========
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. The Sun Fortran 95 implementation explicitly deals with strings as infinitely precise decimal numbers versus strings in which interval width is determined by the last decimal digit in a string.
If the Sun Fortran implementation is standard conforming, or if the draft can be updated to allow the sun string conversion implementation to be standard conforming, I will change my vote to Yes.
See Section 2.9.2 starting on page 98 of Sun's Interval Arithmetic Programming Reference. 

Cheers,

Bill


On 5/30/13 8:48 AM, Ian McIntosh wrote:


I vote YES on Motion 44 Constructors.
- Ian McIntosh IBM Canada Lab Compiler Back End Support and Development