1extern int __isnanf(float f);
2extern int __isnan(double f);
3extern int __isnanl(long double f);
4#define isnan(x) \
5	(sizeof (x) == sizeof (float)                \
6	? __isnanf (x)                    \
7	: sizeof (x) == sizeof (double)               \
8	? __isnan (x) : __isnanl (x))
9
10