Date: Sun, 4 Jan 2015 00:27:03 -0500 From: Pedro Giffuni <pfg@freebsd.org> To: Steve Kargl <sgk@troutmask.apl.washington.edu> Cc: freebsd-numerics@FreeBSD.org Subject: Re: glibc math improvements Message-ID: <CE6A1215-FD5E-4535-9CF7-081649C06898@freebsd.org> In-Reply-To: <20150104043745.GA79370@troutmask.apl.washington.edu> References: <884D1A4A-76B7-4E7B-939A-6FD7D6D6D18D@freebsd.org> <20150104043745.GA79370@troutmask.apl.washington.edu>
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> Il giorno 03/gen/2015, alle ore 23:37, Steve Kargl <sgk@troutmask.apl.washington.edu> ha scritto: > > On Sat, Jan 03, 2015 at 10:00:58PM -0500, Pedro Giffuni wrote: >> >> This blog post was covered by Phoronix: >> http://developerblog.redhat.com/2015/01/02/improving-math-performance-in-glibc/ <http://developerblog.redhat.com/2015/01/02/improving-math-performance-in-glibc/>; >> >> Not sure any of that stuff is applicable to our implementation but it looks like an interesting link to share nevertheless. >> > > AFAICT, it is not applicable. The improvements are in > a 768-bit multi-precision computation of pow() to get an > accurate answer. The article mentions that the technique > may be applied to exp() and log(), but the table-driven > methods that Bruce, David, and I used for logl, expl, and > exp2l are quite accurate (somewhere around ulp < 0.55 or so). > OK, I see, apparently the improvements only apply for worst-case scenarios but we never hit them. A test suite would have been interesting but there is no trace of them in the blog. thanks, Pedro.home | help
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