Path: nntp.eternal-september.org!news.eternal-september.org!eternal-september.org!.POSTED!not-for-mail From: anton@mips.complang.tuwien.ac.at (Anton Ertl) Newsgroups: comp.lang.forth Subject: Re: Parsing timestamps? Date: Mon, 14 Jul 2025 10:11:57 GMT Organization: Institut fuer Computersprachen, Technische Universitaet Wien Lines: 34 Message-ID: <2025Jul14.121157@mips.complang.tuwien.ac.at> References: <1f433fabcb4d053d16cbc098dedc6c370608ac01@i2pn2.org> <878qkvwh3w.fsf@nightsong.com> <874ivjw48w.fsf@nightsong.com> <91e8859d9cb678b7ce7a8a5f341de513@www.novabbs.com> <2025Jul11.122254@mips.complang.tuwien.ac.at> <954cf34891bed0677fd79af0b676c50613dc1443@i2pn2.org> <2025Jul13.110141@mips.complang.tuwien.ac.at> <2d6811168025a74b3ff51a78efb75947d36a0146@i2pn2.org> <2025Jul14.080413@mips.complang.tuwien.ac.at> <87qzyjuqn0.fsf@nightsong.com> Injection-Date: Mon, 14 Jul 2025 12:28:40 +0200 (CEST) Injection-Info: dont-email.me; posting-host="b97952ea380ba87722f1ef4924298ed7"; logging-data="3542083"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX19Z9NXu/Y6KJttBZ4OjZK9D" Cancel-Lock: sha1:HGK6TOLXsLNGqonFInXt0SMEDIU= X-newsreader: xrn 10.11 Paul Rubin writes: >anton@mips.complang.tuwien.ac.at (Anton Ertl) writes: >> So just use the same implementations of transcentental functions, and >> your results will be bit-identical > >Same implementations = same FP operations in the exact same order? Same operations with the same data flow. Independent operations can be reordered. >That >seems hard to ensure, if the functions are implemented in a language >that leaves anything up to a compiler. Even gcc heeds data flow of FP operations unless you tell it with -fastmath that anything goes. >Also, in the early implementations x87, 68881, NS320something(?), >transcententals were included in the coprocessor and the workings >weren't visible. The bigger problem with at least x87 is that math you don't always get bit-identical results even for basic operations such as addition, thanks to double rounding. So even if you implement transcendentals yourself based basic operations, you can see results that are not bit-identical. - anton -- M. Anton Ertl http://www.complang.tuwien.ac.at/anton/home.html comp.lang.forth FAQs: http://www.complang.tuwien.ac.at/forth/faq/toc.html New standard: https://forth-standard.org/ EuroForth 2023 proceedings: http://www.euroforth.org/ef23/papers/ EuroForth 2024 proceedings: http://www.euroforth.org/ef24/papers/