On 8/11/07, Jonathan Bober <[EMAIL PROTECTED]> wrote: > (3a)What I think might be the best idea, at least on Linux, is to change > the compilation settings for quad double so that the fpu fix is not > needed. There are two ways to do this: If a processor supports sse2, > then passing gcc -march=whatever -msse2 -mfpmath=sse (maybe the -march > isn't needed) will cause gcc to use sse registers and instructions for > doubles, and these have the proper precision. In fact, gcc already does > this by default for x86-64 cpus, so the quad double package doesn't even > need the fpu fix on those architectures. Also, this has the added > benefit of being faster. > > (3b)For processors that don't support sse2, gcc can be passed the > -ffloat-store option, which fixes the problem by storing doubles in > memory after every operation, ensuring that they are always correctly > rounded to double precision. This slows things down a little bit, but > would probably be much simpler than option (1). > > Personally, I think that I like options 3a and 3b. These would probably > require rewriting the configure script for quad double. I don't know how > to do that, but it probably isn't that hard.
>From what you say, it sounds like we should *definitely* do 3 if it works, and as soon as possible no less. That said, I am not personally going to do this because I don't understand the issues well enough, or how to test that I haven't messed anything up. I hope somebody will volunteer to create a new quaddouble package that implements your idea *and* tests that it really works. Moreover, whoever does that should definitely write to the quaddouble authors and ask them to add instructions to their README -- currently the quaddouble README strongly suggests that the only option is using their f_fpu_fix_start functions. -- William --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to sage-devel@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sage-devel URLs: http://sage.scipy.org/sage/ and http://modular.math.washington.edu/sage/ -~----------~----~----~----~------~----~------~--~---