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: 103376,54889de51045a215 X-Google-Attributes: gid103376,public X-Google-ArrivalTime: 2003-10-19 09:26:27 PST Path: archiver1.google.com!news2.google.com!news.maxwell.syr.edu!newsfeed.mathworks.com!wn13feed!worldnet.att.net!204.127.198.203!attbi_feed3!attbi_feed4!attbi.com!rwcrnsc51.ops.asp.att.net.POSTED!not-for-mail Message-ID: <3F92BB1A.202@comcast.net> From: "Robert I. Eachus" User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.0.2) Gecko/20021120 Netscape/7.01 X-Accept-Language: en-us, en MIME-Version: 1.0 Newsgroups: comp.lang.ada Subject: Re: += in ada References: <3F7316F7.219F@mail.ru> <17cd177c.0310010606.52da88f3@posting.google.com> <3F8BC74F.2CFBFF37@0.0> <1066312000.671303@master.nyc.kbcfp.com> <1066322883.139702@master.nyc.kbcfp.com> <3F8F372D.9040801@comcast.net> <3F8F4559.50306@noplace.com> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit NNTP-Posting-Host: 24.34.139.183 X-Complaints-To: abuse@comcast.net X-Trace: rwcrnsc51.ops.asp.att.net 1066580786 24.34.139.183 (Sun, 19 Oct 2003 16:26:26 GMT) NNTP-Posting-Date: Sun, 19 Oct 2003 16:26:26 GMT Organization: Comcast Online Date: Sun, 19 Oct 2003 16:26:26 GMT Xref: archiver1.google.com comp.lang.ada:1140 Date: 2003-10-19T16:26:26+00:00 List-Id: Russ wrote: > Oh, I see. So efficiency is no longer an issue. Well, excuse me, but I > think we'd be better off leaving that judgment to each application > developer. Controlling a building temperature is one thing, but > delivering a cruise missile to Saddam Hussein's front door is quite > another. No. Efficiency on the level you are talking about, in Ada, is something we delegate to the compiler. We want software engineers, safety engineers, and security experts to be able to worry about much trickier stuff. Do you want your security experts searching code for potential buffer overruns, or looking for covert timing channels? In Ada, we prefer to leave the stuff that machines can do best to machines. > Do you have any idea whatsoever how much computation is potentially > involved in computing optimal conflict-free trajectories for thousands > of airplanes? Here's a suggestion: if you don't know WTF you are > talking about, STFU. If you would like to get serious on this subject, ask me about an Ada implementation of the assignment problem that used sparse matrices, and a very fast algorithm. (The air traffic control problem is just a huge assignment problem. You want to assign aircraft to airspace most efficiently, subject to the very important constraint that there is at most one airplane in any available airspace. ;-) As for whether or not that work is applicable to air traffic control, it was done as part of the RSIP upgrade of AWACS. A major potential problem was that increasing the radar sensitivity would be useless without the ability to effectively track and manage all that traffic. That is the level at which you should be worrying about efficiency, not the micro efficency of allocating temporaries. And besides, as I said, in modern CPUs, anything you learned about that in school is totally obsolete. That probably includes all classes in Assembler being taught right now. -- Robert I. Eachus "Quality is the Buddha. Quality is scientific reality. Quality is the goal of Art. It remains to work these concepts into a practical, down-to-earth context, and for this there is nothing more practical or down-to-earth than what I have been talking about all along...the repair of an old motorcycle." -- from Zen and the Art of Motorcycle Maintenance by Robert Pirsig