Re: The current proposal

[Ralph Baker Kearfott <rbk@xxxxxxxxxxxxx>]

> Nate Hayes schrieb:
> > > > I think the point Siegfried makes is that the "ideal" mathematical
> > > > properties of the interval arithmetic should drive the implementation,
> > > > not the other way around.
> > > >
> > > > For example, the very simple formula for addition
> > > >
> > > >    [a,b] + [c,d] = [a+c,b+d]
> > > >
> > > > breaks down if c=d=Inf and a=-Inf. In that case, IEEE arithmetic
> > > > produces
> > > >
> > > >    (-Inf,b] + (Inf,Inf) = [NaN,Inf),
> > >
> > > which is indeed the current Intlab result. (No user of Intlab
> > > ever had complained about this meaningless construct; so Siegfried
> > > doesn't have to fear being grilled....)
> >
> > I believe this is a reasonable result in a software implementation, as it
> > becomes very expensive to return something different.
>
> It is quite cheap to convert (Inf,Inf) to NaN before doing the
> operation. This settles the issue within the framework of the Vienna
> Proposal.
>
> And even though this proposal is not the standard to be, it
> rebuts your claim that ''it becomes very expensive to return
> something different''.

I don't know what you talk about.
It only validates what I said: that returning [NaN,Inf) in a software
implementation is cheap and easy.

Nate Hayes
Sunfish Studio, LLC