Re: Inexact floating-point compare

In article <[EMAIL PROTECTED]> [EMAIL PROTECTED] (Nick Maclaren) writes:
 > In article <[EMAIL PROTECTED]>, Dik T. Winter <[EMAIL PROTECTED]> wrote:
 > >In article <[EMAIL PROTECTED]> "Fred J. Tydeman" <[EMAIL PROTECTED]> writes:
...
 > > > the compare is done internally as a subtract, the subtract results in
 > > > an underflow (so two different numbers near the minimum normalized
 > > > value, when subtracted produce a subnormal number) that is then 
 > > > flushed to zero, so compare equal.
 > >
 > >Yup.  But modern machines (IEEE) do not.  ...
 > 
 > A fair proportion of 'IEEE' machines, aren't.  A very common feature
 > is to support denormalised numbers optionally, in software, or not at
 > all.  In all cases, this will usually lead to the comparison of two
 > different denormalised numbers treating them as equal.

Yup, indeed, I can imagine that the processor treats denormal input
for operations as zero, and traps when the flush to zero flag is not
set.  But such numbers can not be the result of an operation in this
case.
-- 
dik t. winter, cwi, kruislaan 413, 1098 sj  amsterdam, nederland, +31205924131
home: bovenover 215, 1025 jn  amsterdam, nederland; http://www.cwi.nl/~dik/