Re: More on trits & tetrits... (long)
On 2010-04-22 17:09:49 -0400, Michel Hack wrote:
> Now you get into trouble defining arithmetic with exact and inexact zeros.
> For example, the inexact zeros resulting from underflow have a valid sign,
> but the sum or difference of two inexact zeros does not. Should that be
> a NaN, just like Inf-Inf?
In floating-point arithmetic, if you have an exact zero and signed
inexact zeros, you need a 4th zero (inexact zero with unknown sign)
and a 3rd infinity (infinity with unknown sign).
In interval arithmetic, such a problem would not occur AFAIK, e.g.
because a positive epsilon would make sense only as the lower bound.
--
Vincent Lefèvre <vincent@xxxxxxxxxx> - Web: <http://www.vinc17.net/>
100% accessible validated (X)HTML - Blog: <http://www.vinc17.net/blog/>
Work: CR INRIA - computer arithmetic / Arénaire project (LIP, ENS-Lyon)