Just for kicks last night I installed gcc3.01 which claims to have Athlon optimization, ie. -march=athlon. I recompiled Python and Numpy, and then ran a big simulation. The new compiler ran 200 seconds slower than the old gcc2.95 with plain -march=pentium. I need to go to the gcc website and see just what optimization they are claiming. Maybe I should have also used -02. Rob. -- The Numeric Python EM Project www.members.home.net/europax