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    Re: Navigation formula problem
    From: Trevor Kenchington
    Date: 2004 Oct 19, 13:54 +0000

    I think something is badly wrong with your numbers. You have the boat
    and the museum differing by about 0.01 degrees of latitude, or around
    1.1 km in northing, as well as by a little over 0.001 degrees of
    longitude or around 68m. So the distance between the two positions, as
    you have quoted them, must be a touch over 1100 metres (I make it
    1109.6), not 685.
    Trevor Kenchington
    You wrote:
    > Hi,
    > I'm currently trying to debug a formula which does the following:
    > Input
    > -----
    > - Position A latitude
    > - Position A longitude
    > - Position B bearing from Position A (Azimuth)
    > - Position B distance from Position A
    > Output
    > ------
    > - Position B latitude
    > - Position B longitude
    > You can check out the formula(e) in a spreadsheet at:
    > http://www.cowcam.com/navigation/PointBposn.xls
    > - Fill in the "Input" in the green cells and you should get "Output" in
    > the lilac ones
    > However, this doesn't match against the following known information (at
    > least according to my GPS and combined with some Great Circle PHP
    > scripting):
    > The boat is located at +52.371987 lat, +4.882612 long
    > The Rijksmuseum at +52.362108 lat, +4.883987 long
    > The distance from the boat to the Rijksmusem is calculated as 0.68456 km
    > The bearing from the boat to the Rijksmuseum is calculated as 175.13 deg
    > The bearing from the Rijksmuseum to the boat is calculated as 355.13 deg
    > I've been playing with the sheet for ages now and can't seem to get it
    > to what the GPS says.
    > Anyone got any ideas? I'd really appreciate it if you do...
    > Thanks in advance,
    > Sam
    Trevor J. Kenchington PhD                         Gadus{at}iStar.ca
    Gadus Associates,                                 Office(902) 889-9250
    R.R.#1, Musquodoboit Harbour,                     Fax   (902) 889-9251
    Nova Scotia  B0J 2L0, CANADA                      Home  (902) 889-3555
                         Science Serving the Fisheries

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