On 11/26/2012 01:29 PM, Paul A. Bristow wrote:
http://gcc.gnu.org/onlinedocs/gcc-4.1.1/gcc/Optimize-Options.html
says
" -ffast-math Sets -fno-math-errno, -funsafe-math-optimizations, -fno-trapping-math,
-ffinite-math-only, <<<<<<<<<<<< so the IEEE pattern for infinity will never be set.
-fno-rounding-math, -fno-signaling-nans and fcx-limited-range.
This option causes the preprocessor macro __FAST_MATH__ to be defined.
"
So I fear that all bets are off as soon as you enable this option.
(and anyway const float a = 0.0f/0.0f; will be optimised away).
And dividing by zero is never a good idea ;-)
That was the fastest way I found to get a nan I would have written: const float a = std::numeric_limits<float>::quiet_NaN(); obtaining the same effect. Gaetano