Re: Motion P1788/M0029.01: Level-3-interface-only --- Final version to vote on
On 2012-01-04 12:47:31 -0800, Dan Zuras Intervals wrote:
> > From: John Pryce <j.d.pryce@xxxxxxxxxxxx>
> > Subject: Re: Motion P1788/M0029.01: Level-3-interface-only --- Final version to vote on
> > Date: Wed, 4 Jan 2012 15:39:06 +0000
> > To: stds-1788 <stds-1788@xxxxxxxxxxxxxxxxx>
> >
> > Vincent
> >
> > On 4 Jan 2012, at 13:08, Vincent Lefevre wrote:
> > > Sorry, I'm quite late in the discussion...
> > > On 2011-12-14 15:37:26 -0800, Dan Zuras Intervals wrote:
> > >> If our compiler people do not object, I think this is an
> > >> excellent idea. The use of "type" as an abstraction &
> > >> "format" as the layout in memory is more in keeping with
> > >> the colloquial use of these words. Therefore, more clear
> > >> to our users.
> > >
> > > Well, in languages, the "type" notion carries more than an abstraction
> > > and even the layout in memory. For instance, in C, you have two
> > > different types "int" and "long", and they are different even if
> > > they have the same properties (same width and so on).
> > >
> > > One needs to be very careful here. For instance, what if you have
> > > an interval encoded by (inf,sup) and another one (-inf,sup), with
> > > the same abstraction (Level 3 is also the same). Would you consider
> > > that since the abstraction is the same, their type (in P1788) is
> > > also the same? If yes, would you allow operations between them?
>
> Vincent,
>
> I feel this brings up a false concern. For any given
> machine one would choose one or another (not both) on
> grounds of efficiency of implementation on THAT machine.
What if the machine provides heterogeneous FPU's? A good example is
the x86, with the conventional FPU and SSE, which can both support
the binary64 format.
--
Vincent Lefèvre <vincent@xxxxxxxxxx> - Web: <http://www.vinc17.net/>
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Work: CR INRIA - computer arithmetic / AriC project (LIP, ENS-Lyon)