Author: Eelco de Groot
Date: 08:28:04 04/30/05
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Hello Dieter, Thanks a lot for the advice and the site with the C-compiler! I will have a look at the compiler from mingw.org. Especially interesting I found all the functions and routines in the Cephes library you mentioned , by Stephen Moshier, for doing extended precision math and astronomy. I once started my own project in Pascal to write routines that could use arrays to do math in any precision you liked, but that is a still unfinished project, exists on paper only, as just a rough outline. For the HP 48 and 49 calculators there are similar routines, developed by Mika Heiskanen and others I believe, also symbolic math packages. Those numbers on the rating list from prof Elo remain a bit of a mystery! Maybe prof. Elo used tables that were not very precise to begin with, and he calculated the elo numbers corresponding to 50.5% to 51.49% as a range for 51% probability etc, rounding the elonumbers. So you get compounded rounding erors? The mathematical routines on available computers in those days were, it seems, still less precise for this purpose than the mathematical tables. I just read an account of the development of the HP 35 calculator in the early seventies (the first electronic slide rule), that calculator was with its ten digit precision more accurate than the IBM mainframes of the day.. (It's a nice site by the way, the HP-museum at http://www.hpmuseum.org/ ) http://www.hpmuseum.org/hp35.htm: "Hewlett-Packard Integrity and "The Bug" The HP-35 had numerical algorithms that exceeded the precision of most mainframe computers at the time. During development, Dave Cochran, who was in charge of the algorithms, tried to use a Burroughs B5500 to validate the results of the HP-35 but instead found too little precision in the former to continue. IBM mainframes also didn't measure up. This forced time-consuming manual comparisons of results to mathematical tables. A few bugs got through this process. For example: 2.02 ln ex resulted in 2 rather than 2.02. When the bug was discovered, HP had already sold 25,000 units which was a huge volume for the company. In a meeting, Dave Packard asked what they were going to do about the units already in the field and someone in the crowd said "Don't tell?" At this Packard's pencil snapped and he said: "Who said that? We're going to tell everyone and offer them, a replacement. It would be better to never make a dime of profit than to have a product out there with a problem". It turns out that less than a quarter of the units were returned. Most people preferred to keep their buggy calculator and the notice from HP offering the replacement." Eelco
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