Date: Sun, 8 Jul 2012 20:13:21 -0600 From: Warner Losh <imp@bsdimp.com> To: Steve Kargl <sgk@troutmask.apl.washington.edu> Cc: Stephen Montgomery-Smith <stephen@missouri.edu>, freebsd-current@freebsd.org Subject: Re: Use of C99 extra long double math functions after r236148 Message-ID: <BD5D9101-99C8-45A5-BE20-1956D257E525@bsdimp.com> In-Reply-To: <20120709020107.GA53977@troutmask.apl.washington.edu> References: <20120528233035.GA77157@troutmask.apl.washington.edu> <4FC40DEA.8030703@missouri.edu> <20120529000756.GA77386@troutmask.apl.washington.edu> <4FC43C8F.5090509@missouri.edu> <20120529045612.GB4445@server.rulingia.com> <20120708124047.GA44061@zim.MIT.EDU> <210816F0-7ED7-4481-ABFF-C94A700A3EA0@bsdimp.com> <4FF9DA46.2010502@missouri.edu> <20120708235848.GB53462@troutmask.apl.washington.edu> <4FFA25EA.5090705@missouri.edu> <20120709020107.GA53977@troutmask.apl.washington.edu>
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On Jul 8, 2012, at 8:01 PM, Steve Kargl wrote: > Not to mention, I've seen way too many examples of 'x - y' > where cancellation of significant digits causes > problems. Throw in rather poor estimates of function > results with real poor ULP and you have problems. Are these problems significantly more or less than the usual #define I = talked about before? If the functions are so so, but much better than = the double version, we have a significant win, even if things aren't = perfect. If we weren't 13 past the publication date of the c99 standard, I'd be = more sympathetic to the 'we need a high quality implementation' = arguments. However, we can't let the perfect be the enemy of the good = here. We claim c99 conformance, yet don't have these functions.=20 After all, many of the original functions that were in our library had = sub-optimial performance which bruce optimized over many years. Why = can't we use this model here? Warner
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