On Wed Aug 21 13:43:54 EDT 2013, ba...@bitblocks.com wrote:
> On Aug 21, 2013, at 9:55 AM, erik quanstrom <quans...@quanstro.net> wrote:
>
> > On Wed Aug 21 12:09:26 EDT 2013, 9f...@hamnavoe.com wrote:
> >>> at least in terms of passing floating point test suites
> >>> (like python's) the NaN issue doesn't come up
> >>
> >> Actually it was a test suite that revealed the NaN errors.
> >> I wouldn't think it's something anyone needs in normal
> >> day-to-day computation, but sometimes boxes must be ticked.
> >
> > :-) it is hard to imagine how this is useful. it's not like
> > ∑{i→∞}-0 is interesting. at least ∏{i→∞}-0 has an alternating
> > sign. (so does it converge with no limit?)
> >
> > the difference i have seen is a situation like
> > atan2(-0, x) ≡ -π
> > atan2(+0, x) ≡ pi, ∀ x<0.
> >
> > any ideas on how this is useful?
>
>
> See comments by Stephen Canon in
> http://stackoverflow.com/questions/1565164/what-is-the-rationale-for-all-comparisons-returning-false-for-ieee754-nan-values
i think you selected a different antecedent for "this" than
i did. by "this" i ment to refer to -0.
- erik
