On Mittwoch, 3. März 2004 04:51, Curtis L. Olson wrote:
> In Linux isnan() is defined in math.h. Is this a portable function (errr
> macro) available to everyone?
I do not remember which standard isnan is according to. I know that SunOS 5.4
and HP-UX 9, all systems from about 4 years ago or older, already had the
isnan function.
But there is an alternative you can use
#define isnan(x) ((x) != (x))
The standard covering floatingpoint arithmetics, IEEE754 requires that this is
equivalent.
Some compilers may optimize such things away with a true value when they are
allowed to violate IEEE754 via compiler flags. I can imaginge that gcc's
-mno-ieee-fp flag does things like that.
For that case create a single small c file containing only this small
function. Compile this one without optimizations and use it ...
Greetings
Mathias
--
Mathias Fröhlich, email: [EMAIL PROTECTED]
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