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=-1.3 required=5.0 tests=BAYES_00,INVALID_MSGID autolearn=no autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 103376,885dab3998d28a4 X-Google-Attributes: gid103376,public From: Ken Garlington Subject: Re: Ariane 5 failure Date: 1996/10/29 Message-ID: <32765410.F6A@lmtas.lmco.com>#1/1 X-Deja-AN: 193051233 references: <96102813151485@psavax.pwfl.com> content-type: text/plain; charset=us-ascii organization: Lockheed Martin Tactical Aircraft Systems mime-version: 1.0 newsgroups: comp.lang.ada x-mailer: Mozilla 2.02 (Macintosh; I; 68K) Date: 1996-10-29T00:00:00+00:00 List-Id: Marin David Condic, 561.796.8997, M/S 731-93 wrote: > > robin writes: > >---The issue was not the addition of a new exception handler. > >The issue was that a magnitude check should have been > >performed on a conversion from double precision floating > >point to 16-bit integer, but it wasn't. > >Of course, having an exceptin handler for this specific purpose > >would have helped, and should have been included as a fallback. > > > > >Assuming that a new exception _handler_ had been added, then it _might > >made > > >a difference. > > > >You can be absolutely certain that it would have helped. > > > procedure ARIANE_FIVE_OPERATION is > X : FLOAT range -65536.0..65535.0 := 65535.0 ; > Y : INTEGER range -32768..32767 := 0 ; > begin > if (X not in -32768.0..32767.0) then > SHUT_DOWN_THE_CHANNEL_AND_PASS_CONTROL_TO_THE_OTHER_SIDE ; --Boom! > else > Y := INTEGER (X) ; > end if ; > end ARIANE_FIVE_OPERATION ; > > *Absolutely* certain? Well, in PL/I, it won't permit an exception handler to shut down the channel. :) (I wasn't going to answer the silly assertion posted above, but I'm glad someone did.) > > Seems that the above algorithm *DOES* have runtime checks to > constrain the assignment of a float to an integer, yet the > accommodation is still a *BAD* engineering decision. We can polish > and polish and polish the software all we want and perform all > sorts of runtime checks, but if the accommodation remains wrong, > we're polishing a turd. > > MDC > > Marin David Condic, Senior Computer Engineer ATT: 561.796.8997 > M/S 731-96 Technet: 796.8997 > Pratt & Whitney, GESP Fax: 561.796.4669 > P.O. Box 109600 Internet: CONDICMA@PWFL.COM > West Palm Beach, FL 33410-9600 Internet: CONDIC@FLINET.COM > =============================================================================== > "If you don't say anything, you won't be called on to repeat it." > > -- Calvin Coolidge > =============================================================================== -- LMTAS - "Our Brand Means Quality" For more info, see http://www.lmtas.com or http://www.lmco.com