Thread Links Date Links
Thread Prev Thread Next Thread Index Date Prev Date Next Date Index

Re: Draft: P1788.1 Standard for Interval Arithmetic (Simplified)

I agree.  A major purpose of the standard is to
unambiguously define a particular behavior, especially
in cases in which different behaviors seem reasonable
for different reasons.  That enables predictability
and portability across platforms.

Giving such an example
would not change the normative part of the standard,
but would definitely clarify it, and thus make
it more valuable.

Baker

On 09/08/2015 03:46 AM, Walter Mascarenhas wrote:

I believe things would be clarified if the standard
stated explicitly the expected result for

    ceil(  [0.5, 1.0]_com )

  and

    ceil( [0.5, 0.75]_com )

All definitions have pros and cons and we have
passed the time to argue about "the best one",
but there should be no ambiguity on the standard
regarding the committee's choice.






On Tue, Sep 8, 2015 at 1:34 AM, Kreinovich, Vladik <vladik@xxxxxxxx
<mailto:vladik@xxxxxxxx>> wrote:

    So here is when we have a confusion: what should we look for:

    * the function is continuous on all the points from the interval

    or

    * the restriction of the function to the interval is continuous

    ceil is a good example when these two things are different

    ________________________________________
    From: stds-1788@xxxxxxxx <mailto:stds-1788@xxxxxxxx>
    [stds-1788@xxxxxxxx <mailto:stds-1788@xxxxxxxx>] on behalf of Oliver
    Heimlich [oliver@xxxxxxxxxxxxxxxxxxx
    <mailto:oliver@xxxxxxxxxxxxxxxxxxx>]
    Sent: Monday, September 07, 2015 10:24 PM
    To: Walter Mascarenhas
    Cc: Ned Nedialkov; IEEEP1788a
    Subject: Re: Draft: P1788.1 Standard for Interval Arithmetic
    (Simplified)

    On 07.09.2015 23:33, Walter Mascarenhas wrote:
     > Are you sure about the following statement in your message?
     >
     >  >> For example: ceil( [0.5, 1]_com ) = [1, 1]_dac, because ceil
    is not
     > continuous in 0.5, but the restriction of ceil is.

    Of course ceil is continuous in 0.5. I was thinking of the function
    roundTiesToAway. However, ceil is not continuous in 1, so the example
    still works.





--

---------------------------------------------------------------
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
---------------------------------------------------------------