Re: [Proj] wrong computation of meridinal distance / pj mlfn.c

Peter Albert peter.albert at
Wed Jul 13 02:11:28 EDT 2005

Hi Cliff,

> Geocentric latitude is not the same as geodetic latitude

well, I thought I correctly incorporated those differences: The geodetic
latitude is what goes into proj and what is used within the approximation in
pj_mlfn.c. However, for the "manual" integration of the elliptical integral
[int(sqrt(a-es*(cos(t)^2)) dt)] you do have to use the geocentric latitude
(it is just based on the ellipse being defined as x=a*cos(t), y=b*sin(t)).
So I used an arbitrary geodetic latitude with proj and the corresponding
geocentric latitude for my calculations. 



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