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 428B33858C5F for ; Thu, 9 Feb 2023 17:49:01 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org 428B33858C5F 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="5.97,284,1669104000"; d="scan'208";a="96384240" Received: from orw-gwy-01-in.mentorg.com ([192.94.38.165]) by esa4.mentor.iphmx.com with ESMTP; 09 Feb 2023 09:48:59 -0800 IronPort-SDR: pfKdtPZgWvUVRbrDQNqBT9GiijsMkxT6UG9p0tk/2b/ssHg7RBEn/QDc0JQnOhX0HvnprjJbTF 1IN04ByL8++zH5ybAfYLNYoMBLxiY6HFDQeInFl8Wdbc5RH6hq3/H7mBFPfNk3CtZLn2TVBZnI MD5fe9ZtbcRiHZSdBTelQHp+CMK+pusqIyFx2h1t4Qepabncej5n4BMPWyq0McHaWHsEaHyiPa 8THCNGZX9cKAj2jq6/OjGa4pIQhlQ5mZGaka+tMkYxtyyUqXl4cYc2tY9E0D2EZ93LQzC0C/Uo BfI= Date: Thu, 9 Feb 2023 17:48:54 +0000 From: Joseph Myers To: Paul Zimmermann CC: Subject: Re: known maximal errors In-Reply-To: Message-ID: <704826d1-1a69-ba2-9398-709d22195910@codesourcery.com> References: MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" X-Originating-IP: [137.202.0.90] X-ClientProxiedBy: svr-ies-mbx-13.mgc.mentorg.com (139.181.222.13) To svr-ies-mbx-10.mgc.mentorg.com (139.181.222.10) X-Spam-Status: No, score=-3108.5 required=5.0 tests=BAYES_00,HEADER_FROM_DIFFERENT_DOMAINS,KAM_DMARC_STATUS,SPF_HELO_PASS,SPF_PASS,TXREP autolearn=no autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: On Thu, 9 Feb 2023, Paul Zimmermann via Libc-alpha wrote: > Hi, > > [1] gives a maximal known error of 0 ulp for hypotf on x86_64, but the > following gives an error of 1 ulp: This is generated from libm-test-ulps files. You can add inputs resulting in larger errors to auto-libm-test-in and regenerate the relevant auto-libm-test-out-* file (and then architecture maintainers should update their libm-test-ulps files as appropriate). If an input results in a larger error than the known maximum, but not large enough to be considered a bug and thus result in test failures whatever is put in libm-test-ulps, then it should be appropriate to add to auto-libm-test-in. > For binary64 sin a maximal known error of 2 ulps is given but I can only > find an error of 0.516 ulps, thus rounding to 1. > Do you have an example with 2 ulps on x86_64 ? libm-test-ulps files aren't often regenerated from scratch (note that they reflect maximal errors for the test inputs across a range of configurations, that may vary in e.g. when the compiler chose to contract operations, or whether an optimized implementation for a particular processor was used, so running the testsuite in a single configuration may not suffice to produce libm-test-ulps that will then result in it passing for all configurations). So they may well contain entries that were correct for a previous version of the code but exceed the maximum error that can occur with the current code. -- Joseph S. Myers joseph@codesourcery.com