On Mon, Oct 06, 2008 at 11:23:32PM -0700, jackfrost wrote: > > > Ian Lance Taylor-3 wrote: > > > > Try -ffast-math. I think it's the default for icc when optimizing. > > Ian > > > > I've tried -ffast-math. > with the same result. Since the two tests are nothing but sin and exp calls respectively, you need to get faster/vector versions of the sin/exp routines. If you are using the development version of the compiler you can use either AMD's optimized math library (acml) or Intel's optimized math library (svml), both of which provide vectorized versions of sin/exp. You will need to download these libraries from AMD or Intel respectively. For the default versions of exp and sin that is in glibc, you will need to talk to the GLIBC folks to get faster versions installed in the library. Faster versions were originally proposed in 2006, and it got bogged down in the glibc process. The person who did the initial work (Evandro Menezes) has since left AMD, but if its important to you, maybe you can work with the GLIBC maintainers to get faster versions in libm. Unfortunately, it is a long process, and can be frustrating at times to satistify all of the accuracy/speed constraints in glibc. -- Michael Meissner, IBM 4 Technology Place Drive, MS 2203A, Westford, MA, 01886, USA meissner@xxxxxxxxxxxxxxxxxx
