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- Newsgroups: comp.lang.ada,comp.lang.c,comp.lang.c++
- Path: newshub.cts.com!crash!telesoft!kst
- From: kst@thomsoft.com (Keith Thompson)
- Subject: Re: C/C++ knocks the crap out of Ada
- X-Nntp-Posting-Host: pulsar
- Message-ID: <DMwFqr.EGD@thomsoft.com>
- Originator: kst@pulsar
- Sender: news@thomsoft.com (USENET News Admin @flash)
- Organization: Thomson Software Products, San Diego, CA, USA
- References: <4etcmm$lpd@nova.dimensional.com> <4f4ptt$a1c@newsbf02.news.aol.com> <4g1b7n$l5@mailhub.scitec.com.au> <JSA.96Feb16135027@organon.com>
- Date: Sat, 17 Feb 1996 02:47:14 GMT
-
- Warning: this is off-topic (but interesting, IMHO).
-
- In <JSA.96Feb16135027@organon.com> jsa@organon.com (Jon S Anthony) writes:
- > In article <4g1b7n$l5@mailhub.scitec.com.au> ramsesy@rd.scitec.com.au (Ramses Youhana) writes:
- > > Didn't NASA loose a satelite due to a bug in a piece of Ada code?
- >
- > I don't think so. I believe that the only confirmed case of a probe
- > loss due to software was a Venus probe which had Fortran code (the
- > problem was a "lexical" error concerning spaces not acting as lexical
- > separators). The recent Mars probe that "vanished" was (last I saw)
- > thought to have been lost due to a small rupture in one of the on board
- > tanks. This caused the ship to go into uncontrolled tumbling. I don't
- > know what it was programmed with.
-
- The story that a Venus probe was destroyed by a Fortran error has been
- widely propagated, but it's inaccurate. The probe in question was
- Mariner 1, which was destroyed 4 minutes after launch on July 22, 1962.
- The real problem was a missing bar in a hand-written guidance equation.
- (A symbol in the equation that should have denoted smoothed velocity data;
- with the missing bar, it instead denoted raw velocity data). This error,
- in combination with a hardware failure, caused the guidance system to
- think the rocket's velocity was fluctuating erratically, when in fact
- it was all right. The automatic correction caused real fluctuations.
- As a result, the range safety operator had to destroy the missile, and
- the probe along with it.
-
- The infamous Fortran error, in which a programmer means to type
- DO 10 I = 1,10
- but instead types
- DO 10 I=1.10
- which, due to Fortran's bizarre lexical rules, is interpreted by the
- compiler as
- DO10I = 1.10
- actually occurred during Project Mercury. An orbit computation program
- with this bug worked well enough for the early suborbital flights, but
- discrepancies started showing up on calculations for the later orbital
- flights. The error was caught before it did any damage.
-
- This is a summary of an article in the RISKS digest (newsgroup
- comp.risks), issue 8.75, dated May 27, 1989. It should be available at
- the comp.risks archive site, <http://catless.ncl.ac.uk/Risks>, but I was
- unable to get through. The information is credited to Paul Ceruzzi's book
- "Beyond the Limits -- Flight Enters the Computer Age".
-
- --
- Keith Thompson (The_Other_Keith) kst@thomsoft.com
- TeleSoft^H^H^H^H^H^H^H^H Alsys^H^H^H^H^H Thomson Software Products
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