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=-1.9 required=5.0 tests=BAYES_00,FREEMAIL_FROM autolearn=ham autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 103376,f039470e8f537101 X-Google-Attributes: gid103376,public X-Google-ArrivalTime: 2003-07-23 22:24:47 PST Path: archiver1.google.com!postnews1.google.com!not-for-mail From: snarflemike@yahoo.com (Mike Silva) Newsgroups: comp.lang.ada Subject: Re: Ariane5 FAQ Date: 23 Jul 2003 22:24:47 -0700 Organization: http://groups.google.com/ Message-ID: <20619edc.0307232124.7324f8f@posting.google.com> References: <1058799152.775376@master.nyc.kbcfp.com> <1058816605.566685@master.nyc.kbcfp.com> <1058969472.350716@master.nyc.kbcfp.com> <1058982513.114816@master.nyc.kbcfp.com> <3F1ED712.2070405@attbi.com> <1058991539.971642@master.nyc.kbcfp.com> <3F1F12FB.2060901@attbi.com> NNTP-Posting-Host: 165.247.220.1 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit X-Trace: posting.google.com 1059024287 27902 127.0.0.1 (24 Jul 2003 05:24:47 GMT) X-Complaints-To: groups-abuse@google.com NNTP-Posting-Date: 24 Jul 2003 05:24:47 GMT Xref: archiver1.google.com comp.lang.ada:40749 Date: 2003-07-24T05:24:47+00:00 List-Id: Hyman Rosen wrote in message news:... > Robert I. Eachus wrote: > > It was if you see this value something is bad wrong, > > and maybe it can be figured out from a data dump. > > But the Ariane 4 code was not written such that a value > exceeding the assumed Ariane 4 range would cause such a > dump. The code was written to assume that the value would > not be exceeded, and to let the code do whatever it might > if the value was exceeded. A value between the spec max > and the overflow min would (probably) not have caused such > a dump. > > The code did "what it was designed to do" only on an Ariane 4. > On the Ariane 5, it did not do "what it was designed to do" > because the design did not cover out of range values. If the > design had covered such values, it would not have specified > one behavior for small large values and a different behavior > for large large values. It's perfectly normal to leave a margin of error, so that values "near" the calculated allowable values are treated in a different and less drastic way than values "far" from the calculated allowable values (and a 64-bit float can range very very "far" from +/-32767). The tradeoff between OTOH rejecting a value that is in reality good, and accepting a value that is in reality bad, is always one that has to be made. The Ariane-4 people were presumably happy with the tradeoff that resulted from the natural buffer which existed between their max calculated value of BH and the inherent range of a 16-bit integer.