From nobody Tue Dec 14 23:14:22 2021 X-Original-To: freebsd-hackers@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id 4FE5718D9BC6; Tue, 14 Dec 2021 23:14:25 +0000 (UTC) (envelope-from sgk@troutmask.apl.washington.edu) Received: from troutmask.apl.washington.edu (troutmask.apl.washington.edu [128.95.76.21]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (2048 bits) client-digest SHA256) (Client CN "troutmask", Issuer "troutmask" (not verified)) by mx1.freebsd.org (Postfix) with ESMTPS id 4JDDjF0n6Wz4p6B; Tue, 14 Dec 2021 23:14:24 +0000 (UTC) (envelope-from sgk@troutmask.apl.washington.edu) Received: from troutmask.apl.washington.edu (localhost [127.0.0.1]) by troutmask.apl.washington.edu (8.16.1/8.16.1) with ESMTPS id 1BENEMOB051104 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NO); Tue, 14 Dec 2021 15:14:23 -0800 (PST) (envelope-from sgk@troutmask.apl.washington.edu) Received: (from sgk@localhost) by troutmask.apl.washington.edu (8.16.1/8.16.1/Submit) id 1BENEMow051103; Tue, 14 Dec 2021 15:14:22 -0800 (PST) (envelope-from sgk) Date: Tue, 14 Dec 2021 15:14:22 -0800 From: Steve Kargl To: Warner Losh Cc: Mark Murray , FreeBSD Hackers , FreeBSD Current Subject: Re: What to do about tgammal? Message-ID: <20211214231422.GA51064@troutmask.apl.washington.edu> References: <20211204185352.GA20452@troutmask.apl.washington.edu> <20211213022223.GA41440@troutmask.apl.washington.edu> <813F29E3-8478-4282-9518-5943DE7B5492@FreeBSD.org> <20211214215106.GA50381@troutmask.apl.washington.edu> List-Id: Technical discussions relating to FreeBSD List-Archive: https://lists.freebsd.org/archives/freebsd-hackers List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-freebsd-hackers@freebsd.org MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Queue-Id: 4JDDjF0n6Wz4p6B X-Spamd-Bar: ---- Authentication-Results: mx1.freebsd.org; none X-Spamd-Result: default: False [-4.00 / 15.00]; REPLY(-4.00)[] X-ThisMailContainsUnwantedMimeParts: N On Tue, Dec 14, 2021 at 03:47:17PM -0700, Warner Losh wrote: > On Tue, Dec 14, 2021 at 3:23 PM Mark Murray wrote: > > > On 14 Dec 2021, at 21:51, Steve Kargl > > wrote: > > > Interval max ULP x at Max ULP > > > [6,1755.1] 0.873414 at 1.480588145237629047468e+03 > > > [1.0662,6] 0.861508 at 1.999467927053585410537e+00 > > > [1.01e-17,1.0661] 0.938041 at 1.023286481537296307856e+00 > > > [-1.9999,-1.0001] 3.157770 at -1.246957268051453610329e+00 > > > [-2.9999,-2.0001] 2.987659 at -2.220949465449893090070e+00 > > > > > > Note, 1.01e-17 can be reduced to soemthing like 1.01e-19 or > > > > Extra diffs most welcome! > > > > Those results have allayed my fears. Is 1e-17 sufficient to commit these > changes, or do > we need to work to get it down to 1e-19 for it to be acceptable? > Well, egg-on-the-face. I updated the sloppy limit to isolate x = 0 from 0x1p-56 to use 0x1p-116 and forgot to update my test scripts. The code in tgammal in the interval [-iota:iota] is if (x > iota) RETURNI(smaller_gam(x)); if (x > -iota) { if (x != 0) u.a = 1 - tiny; /* raise inexact */ RETURNI(1 / x); } so tgammal(x) -> 1/x as x -> 0. -- Steve