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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Bowditch [was Re: Hi (WAS: Re: ping)]
From: Roger M. Derby
Date: 2001 Jan 26, 14:45 EST
From: Roger M. Derby
Date: 2001 Jan 26, 14:45 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.i-DEADLINK-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 > >