[Proj] Accurate algorithm for geodesic calculations

Gerald I. Evenden geraldi.evenden at gmail.com
Sun Mar 1 10:52:47 EST 2009

On Saturday 28 February 2009 5:17:14 pm Charles Karney wrote:
> I've implemented an algorithm for geodesic calculations for an ellipsoid
> with the following features:
>  * It uses expansions accurate to 8th order in the ellipsoid flattening.
>    This gives 12 nm accuracy using doubles and 6 pm accuracy using long
>    doubles.

Ahh!  Nothing like overkilling a subject.   ;-)

Given that all other work with the Earth misses by many order of magnitude the 
need for such precision.

Oh well.


> The code itself (C++ classes and a program for doing geodesic
> calculations) is available at

Not to throw cold water on C++ which I can understand provides a useful 
service in certain applications but I feel that C++ contributes little, if 
anything, to small, limited application procedures.  Certainly, for someone 
with less than expert experience with C++, your code is nearly unreadable 
based upon previous experience.  In the TM code, C++ only obfuscated the 

Again, this is not a language war, only a comment on how to reach the widest 
audience.  Anyone who is an expert in C++ can easily understand a C procedure 
but the reverse in not true.

The whole religious complexion of the modern world is due
to the absence from Jerusalem of a lunatic asylum.
-- Havelock Ellis (1859-1939) British psychologist

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