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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: almanac software
From: George Huxtable
Date: 2002 Mar 9, 06:37 +0000
From: George Huxtable
Date: 2002 Mar 9, 06:37 +0000
>At 6:54 PM +0000 3/8/02, Herbert Prinz wrote: >>Where commercial computer programs are concerned, this is mostly a >>thing of the >>past when computers were so slow and small that one had to make compromises. >>Nowadays, when all almanac programs come on CD roms and need 64 MB of memory >>just to bring the first window onto the screen, there is very little >>justification for truncating the theory of the moon after 200 terms. > >Some of us (Jay and I, at least!) are still producing >commercial almanac software for platforms that don't have CD drives >or 64 MB of memory! > >Hal =============== It really depends what you are running the program on, and for. I have implemented a program for positions of Sun, Moon, 4 planets, and the almanac-stars. The results appear never to exceed 0.2 minutes of arc divergence from the nautical almanac, and this I maintain is adequate for all navigational purposes. Good for the next 50 years, if delta-t is updated from time to time. This has been crammed into 16 kilobytes of memory on a Casio programmable pocket-calculator, now sadly unavailable. But it's dreadfully slow: 5 minutes to get coordinates for the Moon, or Jupiter or Saturn, which are the worst-cases. George Huxtable. ------------------------------ george@huxtable.u-net.com George Huxtable, 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK. Tel. 01865 820222 or (int.) +44 1865 820222. ------------------------------
