Path: csiph.com!weretis.net!feeder6.news.weretis.net!news.misty.com!news.iecc.com!.POSTED.news.iecc.com!nerds-end From: gah4 Newsgroups: comp.compilers Subject: Re: C arithmetic, was Software proofs, was Are there different Date: Thu, 9 Feb 2023 00:37:09 -0800 (PST) Organization: Compilers Central Sender: johnl@iecc.com Approved: comp.compilers@iecc.com Message-ID: <23-02-036@comp.compilers> References: <23-01-092@comp.compilers> <23-02-003@comp.compilers> <23-02-019@comp.compilers> <23-02-025@comp.compilers> <23-02-026@comp.compilers> <23-02-029@comp.compilers> <23-02-034@comp.compilers> MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Injection-Info: gal.iecc.com; posting-host="news.iecc.com:2001:470:1f07:1126:0:676f:7373:6970"; logging-data="44137"; mail-complaints-to="abuse@iecc.com" Keywords: arithmetic, history, comment Posted-Date: 10 Feb 2023 13:16:36 EST X-submission-address: compilers@iecc.com X-moderator-address: compilers-request@iecc.com X-FAQ-and-archives: http://compilers.iecc.com In-Reply-To: <23-02-034@comp.compilers> Xref: csiph.com comp.compilers:3377 On Wednesday, February 8, 2023 at 8:50:19 AM UTC-8, Hans-Peter Diettrich wrote: (snip) > That's correct, the inprecise representation of FP numbers allows for > such tricks. The hidden bit trick can be used again with the FP > exponents, as I outlined in my Dynamic Floating Point Exponents proposal To continue discussion about OoO and the 360/91, S/360 specifies floating point divide with a truncated quotient. The 91 uses a Newton-Raphson divide algorithm, using its high-speed multiplier, to generate a rounded quotient. Along with imprecise interrupts, that is on the list of incompatibilities with other S/360 models. As for hidden bit, S/360 uses base 16 floating point, so no hidden bit. [I actually programmed a /91 in Fortran, so, yeah. -John]