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

[Philip Nienhuis]

Follow-up Comment #7, patch #10021 (project octave):

I read (IIRC on wikipedia) that the formulas generally used for this operation
(due to Vincenty) tend to break down on antipodal points [*].
Yet reckon.m seems to do fairly well for that case. Surprising as I found that
is is not very accurate in some other cases (not quite corner cases).
Where did you get the used equations from? couldn't find a reference in the
code.

I already had inserted 'wrapToPi (az)' as L.142 (see comment #4) but it didn't
make much difference here, still imaginary longitudes.

Indeed, I figured the erroneous longitudes would be due to a quadrant /
principal value issue.

I really hope the issues can be solved. geodeticfwd.m seems a very useful
function to me.

[*] https://en.wikipedia.org/wiki/Geodesics_on_an_ellipsoid

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