NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Haversine formulae for Great Circles
From: Chuck Taylor
Date: 2001 Nov 18, 11:08 AM
From: Chuck Taylor
Date: 2001 Nov 18, 11:08 AM
George Huxtable wrote: > What an interesting contribution from Lu Abel! (copied below). Perhaps I > can add something to it. And you have, George. Thanks. One minor point. You wrote: > Lu has pointed to a difficulty in the use of the standard great-circle > distance formula. ... > > Even with this high > accuracy, distances of 0.1 nautical miles have started to go a bit > inaccurate, and distances which should be .01 miles are calculated as zero. > With a computer using single-precision, things would be a lot worse. So the > problem Lu has raised is a real one, in these special circumstances of > close approach. Why would one be interested in great circle routes for such short distances? Mercator Sailing or Mid-Latitude Sailing would seem much more applicable for distances under, say, 60 nautical miles. Chuck Taylor Everett, WA, USA
