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    Re: Direct methods
    From: Michael Dorl
    Date: 2007 Nov 05, 05:58 -0600

    At 03:43 PM 11/4/2007, you wrote:
    >Michael Dorl wrote-
    >| Back in 1999, I sat down and worked out the spherical trig for this
    >| problem.  It may be found at
    >| http://ns.doit.wisc.edu/~mdorl/Sight%20Reduction%20write%20up.doc
    >| I am pretty sure it handles all the quadrant problems  I did not consider
    >| problems at angles when the trig functions misbehave.
    >That's interesting, and timely. Except in detail, it's on exactly the same
    >lines as the procedure quoted in John Karl's book. Understand one , and you
    >will understand the other.
    >However, one of those details is a silly error in Michael Dorl's program, in
    >which his final equation for Cos(T), on the last page, should  not be-
    >cos(T) = [Sin(AltJ)-Cos(DeclJ)Sin(Lat)] / Cos(DeclJ)Cos(Lat)
    >but instead-
    >cos(T) = [Sin(AltJ)-Sin(DeclJ)Sin(Lat)] / Cos(DeclJ)Cos(Lat)
    >Mike will kick himself when he sees it! Making that change, and allowing for
    >different notation, his equations for Sin(Lat) and for Cos(T) then
    >correspond EXACTLY with John Karl's 7.5d and 7.5e.
    Well shucks :-(  I did have it right in the c++ program so I must have made
    the error when I wrote up the description.
    Many thanks for pointing it out, I will fix it.
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