Hello, Marc Collin schrieb:
-ffast-math
Note that this requires a carefully written program otherwise it may not work reliably. From reading *@gcc.gnu.org and from the manpage ("This option should never be turned on by any -O option since it can result in incorrect output for programs which depend on an exact implementation of IEEE or ISO rules/specifications for math functions.") I think one should be really careful with this option. For my calculations, I don't dare it to use it - better 1% slower and correct than (potentially) 100% wrong and 1% faster.* For non-number crunching programs I would even be more careful. Tobias *In similar regard: Using GCC gfortran compiled Netlib LAPACK [SUSE's lapack.rpm] with the Intel Fortran Compiler (ifort) versus using the Intel Math Kernel Library mit ifort: With one of my programs the speedup was around one percent. [Ok, with one program: ifort compiled is 20% faster than gfortran compiled.] --------------------------------------------------------------------- To unsubscribe, e-mail: opensuse-factory+unsubscribe@opensuse.org For additional commands, e-mail: opensuse-factory+help@opensuse.org