From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on inbox.vuxu.org X-Spam-Level: X-Spam-Status: No, score=-3.0 required=5.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED,RCVD_IN_MSPIKE_H3, RCVD_IN_MSPIKE_WL autolearn=ham autolearn_force=no version=3.4.2 Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by inbox.vuxu.org (OpenSMTPD) with SMTP id 058ee5fc for ; Wed, 12 Feb 2020 04:07:33 +0000 (UTC) Received: (qmail 18303 invoked by uid 550); 12 Feb 2020 04:07:32 -0000 Mailing-List: contact musl-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Reply-To: musl@lists.openwall.com Received: (qmail 18282 invoked from network); 12 Feb 2020 04:07:31 -0000 X-Authentication-Warning: key0.esi.com.au: damianm owned process doing -bs Date: Wed, 12 Feb 2020 15:07:17 +1100 (AEDT) From: Damian McGuckin To: musl@lists.openwall.com In-Reply-To: <20200212020023.GV1663@brightrain.aerifal.cx> Message-ID: References: <20200211193059.GH23985@port70.net> <20200211232432.GU1663@brightrain.aerifal.cx> <20200212020023.GV1663@brightrain.aerifal.cx> User-Agent: Alpine 2.02 (LRH 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; format=flowed; charset=US-ASCII Subject: Re: [musl] casinh function accuracy problem On Tue, 11 Feb 2020, Rich Felker wrote: > My minimal criterion for large-scale improvements of src/complex would > be fixing any remaining cases where inf/nan behavior is badly wrong or > there's catastrophic error (>2^52 ulp, or even just >2^20 ulp or so). > Beyond that, I think "reducing ulp error" would be nice but hard to > quantify and make a goal without having an idea how bad it is now, not > to mention without having rigorous error bounds on the real math > library functions. I think INF/NaN behaviour at the fundamental level is flawed. This initialization: double complex x = 1.0e+200 + INFINITY * I; on every compiler I try, yields an 'x' of NaN + INFINITY i Whereas if I compute double complex a = 2.0 + 1.0e200 * I; double complex b = 1.0e200 + 1.0 * I; double x = a * b; then 'x' prints correctly as 1.0e+200 + INF * I; Regards - Damian Pacific Engineering Systems International, 277-279 Broadway, Glebe NSW 2037 Ph:+61-2-8571-0847 .. Fx:+61-2-9692-9623 | unsolicited email not wanted here Views & opinions here are mine and not those of any past or present employer