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Subject: Re: Bowditch [was Re: Hi (WAS: RE: ping)]
From: Roger M. Derby (derbyrm@XXX.XXX)
Date: Fri Jan 26 2001 - 14:45:11 EST
Just a word of caution that I'm sure is unnecessary. When I was programming
a VAX to do great-circle calculations (path length and departure) using the
equations from Bowditch, I got some very strange results. These turned out
to be caused by the machine's math library making different assumptions
about quadrant than was used by Bowditch. I finally made up a table of
entries for two points a few nm apart using paths that hit all four
quadrents and the four cardinal points and then checking against
"reasonable" answers. Had to add several IF-THENs before Singapore was a
long way from the Lizard and in the correct direction.
Roger
----- Original Message -----
From: "Hal Mueller" <hal@XXX.XXX>
To: <NAVIGATION-L@XXX.XXX>
Sent: Friday, January 26, 2001 2:25 PM
Subject: [NAV-L] Bowditch [was Re: Hi (WAS: RE: ping)]
> >I don't have Bowditch yet, but I do have the French
> >admiralty manuals and I don't see why the formulas would not yield the
same
> >results?
>
> I would hope they would! :P
>
> I note, also, that the 1995 edition of Bowditch is online in PDF
> format at http://www.irbs.com/bowditch/. At first glance the
> sections containing formulas look better organized and more tightly
> written than in my hardcopy 1977 edition.
>
> Oh yeah, regarding forms: is there something on the Handspring site
> to preview your forms? Their dev tools (free) are at
> http://www.handspring.com/developers/sw_dev.jhtml. I use
> Codewarrior, so haven't explored the Handspring stuff.
>
> H
>
> ----
> Hal Mueller hal@XXX.XXX
> Mobile Geographics LLC http://www.mobilegeographics.com/
> Seattle, Washington (206) 297-9575
>
>
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