Path: csiph.com!xmission!usenet.csail.mit.edu!news.iecc.com!.POSTED.news.iecc.com!nerds-end From: Hans-Peter Diettrich Newsgroups: comp.compilers Subject: Re: C arithmetic, was Software proofs, was Are there different Date: Wed, 8 Feb 2023 15:24:55 +0100 Organization: Compilers Central Sender: johnl@iecc.com Approved: comp.compilers@iecc.com Message-ID: <23-02-034@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> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Injection-Info: gal.iecc.com; posting-host="news.iecc.com:2001:470:1f07:1126:0:676f:7373:6970"; logging-data="12088"; mail-complaints-to="abuse@iecc.com" Keywords: arithmetic Posted-Date: 08 Feb 2023 11:50:16 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: <23-02-029@comp.compilers> Xref: csiph.com comp.compilers:3375 On 2/7/23 2:31 PM, Hans-Peter Diettrich wrote: > On 2/6/23 10:26 PM, gah4 wrote: > >> Too bad for those CDC computers, and Unisys computers. >> Last I know of sign-magnitude is the IBM 7090 and 7094. > > AFAIK use IEEE-754 floating point numbers still sign-magnitude > representation. > Then the same representation of integral numbers may have advantages in > computations. > > DoDi > [I presume the sign-magnitude is to enable the hidden bit trick, > which doesn't apply in unscaled integers. -John] 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 . DoDi