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,d901a50a5adfec3c X-Google-Attributes: gid103376,public X-Google-Thread: 1094ba,9f0bf354542633fd X-Google-Attributes: gid1094ba,public From: William Clodius Subject: Re: Fortran or Ada? Date: 1998/09/30 Message-ID: <361241FC.2847@lanl.gov>#1/1 X-Deja-AN: 396351142 Content-Transfer-Encoding: 7bit References: <36068E73.F0398C54@meca.polymtl.ca> <6u8r5o$aa4$1@nnrp1.dejanews.com> <360A3446.8AD84137@lmco.com> <6udre0$ha1$1@nnrp1.dejanews.com> <19980925.185359.250@yktvmv.watson.ibm.com> <6uifdr$dog$1@nnrp1.dejanews.com> <19980928.184428.604@yktvmv.watson.ibm.com> <19980929.214309.386@yktvmv.watson.ibm.com> Content-Type: text/plain; charset=us-ascii Organization: Los Alamos National Lab Mime-Version: 1.0 Newsgroups: comp.lang.fortran,comp.lang.ada Date: 1998-09-30T00:00:00+00:00 List-Id: jbs@yktvmv.watson.ibm.com wrote: > > The accident report indicates that they deliberately > chose not to do it in this case because they were worried about > performance. This would seem to indicate that turning off the > error check is not cheap (in terms of performance). > James B. Shearer I repeat: "For reasons of reliability computer systems on rockets and satellites are implemented using processors that are several generations behind commercial processors in performance. Also, there is always a tendency to add features so that system utilization closely matches maximum allowed utilization. As a result every potential and unnecessary increase in processor load is avoided however small. However, this was only one of several reasons given for not protecting this value. Protecting this value (for the Ariane 4) was viewed as unnecessary and dangerous. Quoting the report. "The reason for the three remaining variables, including the one denoting horizontal bias, being unprotected was that further reasoning indicated that they were either physically limited or that there was a large margin of safety, a reasoning which in the case of the variable BH turned out to be faulty. It is important to note that the decision to protect certain variables but not others was taken jointly by project partners at several contractual levels." -- William B. Clodius Phone: (505)-665-9370 Los Alamos Nat. Lab., NIS-2 FAX: (505)-667-3815 PO Box 1663, MS-C323 Group office: (505)-667-5776 Los Alamos, NM 87545 Email: wclodius@lanl.gov