[Octave-patch-tracker] [patch #10021] [octave forge] (mapping) meridianfwd

[Philip Nienhuis]

Follow-up Comment #22, patch #10021 (project octave):

Progress report:

After some (much) more experimenting with vincentyDirect.m, vincenty.m, and
after trying various examples I got a bit confused.
The test examples in the original geodeticfwd.m (from the comment #0) can't be
exactly reproduced by vincentyDirect.m as it stands.  The difference is about
10 km. But it looks like the original geodeticfwd.m was based on too simple
calculation methods. Anyway this needs to be sorted out before further work on
meridianfwd.m can continue.
That said, for angle displacement inputs vincentyDirect.m turns out to return
quite exact answers AFAICS. Inputting vincentyDirect.m's output into vicenty.m
and vice versa fairly exactly reproduces the input displacement and end
coordinates, resp.

In the mean time I improved the "new" geodeticfwd.m:
* absorbed the actual vincentyDirect.m code into it; geodeticfwd.m isn't a
wrapper for vincentyDirect.m anymore but self-contained;
* vectorized the code so multiple displacements can be computed relatively
rapidly in one call;
* geodeticfwd.m accepts scalars, vectors and 2D/ND arrays, provided all input
vectors and arrays match regarding sizes and dimensions. Scalars on the one
hand and vectors/arrays OTOH can be mixed;
* also check the ellipsoid LengthUnit to match that of the "length" input (to
avoid a potentially deceiving issue with length units).
These last changes are here:
http://hg.code.sf.net/p/octave/mapping/rev/347c2ac91480
There are still pending improvements: more BIST (esp. input validation),
remove some debug statements; maybe ellipsoid validity checks. That'll happen
later this week.

I did this to just leave A. Foltran's version as much as possible his work; I
intend to keep vincentyDirect.m in the mapping package for at least some
time.


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