newlib-cygwin/winsup/cygwin/math/isnan.c

int
isnan (double x)
{
  return __builtin_isnan (x);
}

int
isnanf (float x)
{
  return __builtin_isnan (x);
}

int
isnanl (long double x)
{
  return __builtin_isnan (x);
}