On Fri, 9 Jun 2006, Vladimir G. Ivanovic wrote: > > On Fri, 2006-06-09 at 07:47 +0200, Michael Weyershäuser wrote: > > I don't recommend -ffast-math on a global basis (or at all), it gets you > > right where the Pentium fdiv bug brought us some years ago: floating > > point operations will be faster, but they could get a wrong result in > > some occasions... > > Linus seems to use -ffast-math: > http://gcc.gnu.org/ml/gcc/2001-07/msg02150.html. At least in 2001 he > did.
I use it too, in my numerical simulations of the Schroedigner equation, I think it is fairly standard in the numerics community. My understanding is that it results in a fairly consistent and predictable loss of precision for some operations, nothing like the catastrophic *errors* in the the intel fdiv bug. Of course, for algorithms that are sensitive to precision, it can (and does) cause problems. Cheers, Ian
