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    Re: Haversine formulae for Great Circles
    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
    

       
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