On 2010-02-16 15:39:31 +0100, Christoph Groth wrote: > Thank you all very much for clarifying this issue. I am very much > surprised that x87 instructions behave differently on AMD and Intel > processors but this seems indeed to be the case. That's for elementary functions only (e.g. fsincos here). On http://www.vinc17.net/research/testlibm/ you can see that different platforms give different results. Differencies may be due to the OS, the C library and/or the hardware. Note that on x86_64 machines, sin and cos are correctly rounded (this is not proved, but probably true in practice, assuming no bugs in the implementation). I wonder why GCC doesn't use these functions by default instead of glibc's sincos (which could be enabled only with an option like -ffast-math). -- Vincent Lefèvre <vincent@xxxxxxxxxx> - Web: <http://www.vinc17.net/> 100% accessible validated (X)HTML - Blog: <http://www.vinc17.net/blog/> Work: CR INRIA - computer arithmetic / Arénaire project (LIP, ENS-Lyon)
