From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=0.2 required=5.0 tests=BAYES_00,INVALID_MSGID, REPLYTO_WITHOUT_TO_CC autolearn=no autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: ffc1e,a48e5b99425d742a X-Google-Attributes: gidffc1e,public X-Google-Thread: fac41,a48e5b99425d742a X-Google-Attributes: gidfac41,public X-Google-Thread: f43e6,a48e5b99425d742a X-Google-Attributes: gidf43e6,public X-Google-Thread: 1108a1,5da92b52f6784b63 X-Google-Attributes: gid1108a1,public X-Google-Thread: 103376,a48e5b99425d742a X-Google-Attributes: gid103376,public From: kennel@nospam.lyapunov.ucsd.edu (Matt Kennel (Remove 'nospam' to reply)) Subject: Re: Papers on the Ariane-5 crash and Design by Contract Date: 1997/03/20 Message-ID: #1/1 X-Deja-AN: 226915421 References: <332B5495.167EB0E7@eiffel.com> <332D113B.4A64@calfp.co.uk> <5gm8a6$2qu$2@news.irisa.fr> Organization: The University of California at San Diego Reply-To: kennel@nospam.lyapunov.ucsd.edu Newsgroups: comp.lang.eiffel,comp.object,comp.software-eng,comp.programming.threads,comp.lang.ada Date: 1997-03-20T00:00:00+00:00 List-Id: Hmm. Doesn't it seem that the proper course for something like the overflow error would have been to set the result to a "NaN"?? This may propagate undesirably through part of the system, but the control software could realize that and proceed to use 'uncontaminated' inputs. Non-signalling 'NaN's are usually undesirable for running scientific research codes. We tend to get really upset when our hour long jobs do nothing but print out a datafile of NaN's, especially when the low-level signal handling on many CPUs mean the run will be extra-slow. As it would happen, the standard compiler options on workstations make silent NaN's the norm (where they are usually dumb), but yet the "abort everything upon overflow" was done on a rocket controller where continuing NaN's would be more useful. Murphy's cackling his head off. -- Matthew B. Kennel/Institute for Nonlinear Science, UCSD/ Don't blame me, I voted for Emperor Mollari.