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    Re: Almanacs, theory and use.
    From: Fred Hebard
    Date: 2007 Nov 21, 08:57 -0500

    the assumed position has to be fairly close to your actual position
    to work.  If your longitude is out 180 degrees, it might even be off
    180 degrees (there are two intersections of the circles of position
    on the globe).  Even if you chose the right point of intersection,
    you have to be fairly close, a few degrees.  What you can do then is
    take the newfound position as a second assumed position and rework
    the calculation.
    
    On Nov 21, 2007, at 5:29 AM, Isonomia wrote:
    
    >
    > Thanks again for all the links.
    >
    > I've worked out how it is possible to use a simple table to calculate
    > azimuth.
    >
    > My confusion came about because I read that the "assumed position" was
    > an arbitrary position, however given that a 3 significant digit cosine
    > take one page in a log table, then for an arbitrary two angle sum, one
    > is talking about hundreds of pages for a 4 significant figure double
    > angle table.
    >
    > From what I understand so far, the assumed position isn't arbitrary,
    > but is a whole number of degrees away from the geographic position,
    > making the tables much much smaller (by some 3600x)
    >
    > To be in simply, I was misled into believing the assumed position was
    > something to do with the desired outcome, rather than a simplification
    > of the calculation!
    >
    >
    > >
    
    
    
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