Advice from someone who knows much more than me:
> C99 does not offer either issubnormal() or iszero(). > > Since C99 mode is in use, both issubnormal() and iszero() can be easily > implemented with the C99 fpclassify() classification macro: > > #include <math.h> > #undef issubnormal > #define issubnormal(x) (fpclassify(x) == FP_SUBNORMAL) > #undef iszero > #define iszero(x) (fpclassify(x) == FP_ZERO) > > No need to rely on anything Sun/Linux-specific, really.
