On 02/17/2010 02:26 PM, Vincent Lefevre wrote: > 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). Maybe this is a bug. There is a version of sincos in the IBM Accurate Mathematical Library but it's not used in this case. Andrew.
