Re: How do I bisect unbounded intervals?
> Date: Fri, 13 Jan 2012 00:29:21 -0500
> To: stds-1788 <stds-1788@xxxxxxxxxxxxxxxxx>
> From: Michel Hack <hack@xxxxxxxxxxxxxx>
> Subject: Re: How do I bisect unbounded intervals?
>
> Dan Zuras wrote:
> > Someone suggested an information theory midpoint. In
> > floating-point this is quite close to a geometric mean
> > in that it finds that floating-point number for which
> > the number of representable numbers between lo & mid
> > is nearly equal to the number between mid & hi.
> >
> > There is merit in this but I would not give it the name
> > "midpoint". Perhaps "split".
>
> Neat! Convert both endpoints to sortable, take the average,
> and convert back to floating-point! ("Sortable" is a crude but
> invertible transformation that permits basic string comparison
> to be applied to the bits. On big-endian machines for binary
> formats this involves inverting the sign bit and, if the input
> was negative, inverting all other bits as well. For DFP it's a
> bit more complicated but still doable.) (NaNs need to be dealt
> with first, or they would be bigger than infinity.)
>
> (This is unfortunately a Level 4 concept. Well, we are supposed
> to avoid Level 3 issues, but nobody said anything about Level 4!)
>
> Michel.
Which is why I said, & I quote,
"But that's about all I can say about it & still
be on the topic of standardizable things. :-)"
The smiley was more for irony than humor. :-)
So let's drop this topic now & get back to our day job.
OK?
Dan