[PROJ] Cassini-Soldner ellipsoid form bug ?

[Michael Sumner]

I'm having trouble with Cassini-Soldner:

# Good point - agreeable coords
echo "-6 -71" | proj +proj=cass +R=6378137        # spherical  -217097.18
-7914445.72
echo "-6 -71" | proj +proj=cass +ellps=WGS84      # ellipsoidal -217749.76
-7891343.23

# Bad point - ellipsoidal diverges
echo "149 45" | proj +proj=cass +R=6378137        # spherical: 2377511.89
14538559.49
echo "149 45" | proj +proj=cass +ellps=WGS84      # ellipsoidal:
-2738664.72 28023005.14 (WRONG)

That second coordinate seems wildly wrong, I've compared with GeographicLib
which shows

lon,lat,x,y
-6.000000,-71.000000,-217749.757184,-7891343.215151
149.000000,45.000000,2381489.299010,14528505.93346

I've laid out a longer description exploring this (and includes the C++
wrapper for GeographicLib):

https://github.com/mdsumner/projcassini

I hope that's enough to show the problem, I found this very confusing but
the output of GeographicLib makes me more confident.

Cheers, Mike

-- 
Michael Sumner
Research Software Engineer
Australian Antarctic Division
Hobart, Australia
0438489030
e-mail: mdsumner at gmail.com
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