From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 43561 invoked by alias); 12 Mar 2018 16:10:28 -0000 Mailing-List: contact libc-alpha-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: libc-alpha-owner@sourceware.org Received: (qmail 43543 invoked by uid 89); 12 Mar 2018 16:10:27 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-2.0 required=5.0 tests=AWL,BAYES_00,RCVD_IN_DNSWL_NONE,SPF_PASS,URIBL_RED autolearn=ham version=3.3.2 spammy= X-HELO: relay1.mentorg.com Date: Mon, 12 Mar 2018 16:10:00 -0000 From: Joseph Myers To: Wilco Dijkstra CC: Steve Ellcey , Zack Weinberg , =?ISO-8859-2?Q?Ond=F8ej_B=EDlka?= , Siddhesh Poyarekar , "libc-alpha@sourceware.org" , nd Subject: Re: [PATCH 2/6] Remove slow paths from sin/cos In-Reply-To: Message-ID: References: <1520636722.6774.157.camel@cavium.com>, User-Agent: Alpine 2.20 (DEB 67 2015-01-07) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" X-ClientProxiedBy: svr-ies-mbx-01.mgc.mentorg.com (139.181.222.1) To svr-ies-mbx-01.mgc.mentorg.com (139.181.222.1) X-SW-Source: 2018-03/txt/msg00289.txt.bz2 On Mon, 12 Mar 2018, Wilco Dijkstra wrote: > Though these patches keep the ULP accuracy across the full range as is, > we could agree on higher ULP errors for large/huge range reduction cases > in the future. The main complexity is for certain rare inputs which happen to > be extremely close to an integer multiple of PI/2, and those few cases mean > you need significant extra work to guarantee 0.5 ULP error bound on range > reduction. I don't think the work for having an error bound not much more than 0.5ulp on the final result of sin/cos for large arguments is significantly different from the work for having an error bound of say 3ulp (the testsuite has a global maximum of 9ulp (16ulp for IBM long double) beyond which it will not accept errors even if those large errors are listed in libm-test-ulps files - that bound is simply based on the errors empirically observed at present, for functions other than Bessel functions and cpow which are known to have cases with much larger errors). -- Joseph S. Myers joseph@codesourcery.com