On 2012-02-03 16:57:19 +0100, Michael Matz wrote: > > And it may be important that some identities (like cos^2+sin^2=1) be > > preserved. > > Well, you're not going to get this without much more work in sin/cos.
If you use the glibc sin() and cos(), you already have this (possibly up to a few ulp's). > > For the glibc, I've finally reported a bug here: > > > > http://sourceware.org/bugzilla/show_bug.cgi?id=13658 > > That is about 1.0e22, not the obscene 4.47460300787e+182 of the original > poster. But 1.0e22 cannot be handled correctly. > Btw, the correct results for sin are about .7021835074240, and > cos about -.71199601256024, so the sum is about -.0098125051362. His math > library didn't get these results in either way. Nevertheless it doesn't > make sense to require such precision for these input for a math library > intended to be used for normal means. That's just your opinion. > If you want to have precise numbers use an arbitrary precision math > library. This is double precision. An arbitrary precision math library (even though I develop one) shouldn't be needed. -- Vincent Lefèvre <vinc...@vinc17.net> - Web: <http://www.vinc17.net/> 100% accessible validated (X)HTML - Blog: <http://www.vinc17.net/blog/> Work: CR INRIA - computer arithmetic / AriC project (LIP, ENS-Lyon)
