On 2010-02-22 05:23:39 +0100, Vincent Lefevre wrote:
> On 2010-02-22 02:58:19 +0000, Joseph S. Myers wrote:
> > For example, N1421 (Markham minutes) has a discussion that's clearly
> > presuming that a conditional
> >
> > #if defined(__STDC_IEC_559__) && (FLT_EVAL_METHOD == 1)
> >
> > may hold.
>
> Well, this is a bit unclear. I think this is OK, as long as rounding
> of a float operation is done to single precision (the exponent range
> may still be the one of the double format, in which case the value of
> FLT_EVAL_METHOD should be 1 as above). IEEE 754-1985 says:
[...]
Hmm... This doesn't seem to be allowed by the C language, though,
as C99 says for FLT_EVAL_METHOD == 1:
evaluate operations and constants of type float and double to the
range and precision of the double type,
^^^^^^^^^^^^^
So, this means that the precision of the double type should be single
precision in this case, but this is not allowed.
--
Vincent Lefèvre <vinc...@vinc17.net> - Web: <http://www.vinc17.net/>
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Work: CR INRIA - computer arithmetic / Arénaire project (LIP, ENS-Lyon)
