From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from esa4.mentor.iphmx.com (esa4.mentor.iphmx.com [68.232.137.252]) by sourceware.org (Postfix) with ESMTPS id 0C6763858D1E for ; Wed, 17 Aug 2022 16:52:41 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 0C6763858D1E Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=codesourcery.com Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=mentor.com X-IronPort-AV: E=Sophos;i="5.93,243,1654588800"; d="scan'208";a="81464142" Received: from orw-gwy-02-in.mentorg.com ([192.94.38.167]) by esa4.mentor.iphmx.com with ESMTP; 17 Aug 2022 08:52:41 -0800 IronPort-SDR: 8WW7i9610XiSPhlQlLl9+RIeNu67n6kDEguYBENkTbDCCA9EoOxmZt10hWLGk4/3rRoB3N+rVK xZyY3ZPwdKPkHf3wA0jbFp5eN2pf6n34qEYdhFZcIxGEk/5Oy9oOnc1025RXR3+qLSwuPnfULW az+dgO0StzIWhn7mikip1RzL1/ghr0HxlLrD6PxB4TPHHoAFyRUPLdSDA2K3ziYSJGHWgbVxiC 4ctugxc83el57fYyi/TZLgNcTGP3QSv52qJ5zOEjtRMnH6YsDJInSCC9brBgH+kfviLsWwzgcq Hr8= Date: Wed, 17 Aug 2022 16:52:36 +0000 From: Joseph Myers X-X-Sender: jsm28@digraph.polyomino.org.uk To: Wilco Dijkstra CC: Michael Hudson-Doyle , GNU C Library Subject: Re: [PATCH] Ensure calculations happen with desired rounding mode in y1lf128 In-Reply-To: Message-ID: References: User-Agent: Alpine 2.22 (DEB 394 2020-01-19) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" X-Originating-IP: [137.202.0.90] X-ClientProxiedBy: svr-ies-mbx-14.mgc.mentorg.com (139.181.222.14) To svr-ies-mbx-10.mgc.mentorg.com (139.181.222.10) X-Spam-Status: No, score=-3111.5 required=5.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS, KAM_DMARC_STATUS, KAM_NUMSUBJECT, SPF_HELO_PASS, SPF_PASS, TXREP, T_SCC_BODY_TEXT_LINE autolearn=no autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 17 Aug 2022 16:52:43 -0000 On Wed, 17 Aug 2022, Wilco Dijkstra via Libc-alpha wrote: > When you design a polynomial to be very accurate, it actually works in > all rounding modes without extra effort. For this function it seems like In the Bessel function case, accurate results near zeros in the intermediate range (the range where multiple terms of a series are needed before applying range reduction, see Harrison's paper ) may require extra internal precision when computing the phase. And some precision extension techniques only work in round-to-nearest (we only have that Bessel function approach implemented in glibc for float, where using double internally avoids such rounding mode problems for precision extension). -- Joseph S. Myers joseph@codesourcery.com