Inverse +proj=cass: fix non-convergence on inputs where easting=false_easting or northing=false_northing

[rouault]

Fixes #4385

For a unknown reason, a test in pj_generic_inverse_2d() was skipping adding the iterative correction terms when the input was such that easting=false_easting or northing=false_northing, causing the function to do nothing useful and fail after its maximum allowed number of iterations was reached. The remove tests might or might not have been needed... Only future will tell...

[jjimenezshaw]

pj_generic_inverse_2d is used in
src/projections/cass.cpp
src/projections/adams.cpp (three times)
src/projections/wink2.cpp

Should we test those projections in that circumstance as well?

[rouault]

Should we test those projections in that circumstance as well?

Seems to work fine.

$ echo 0 0 | bin/proj +proj=adams_ws2 +x_0=100000 +y_0=200000 | bin/proj -I +proj=adams_ws2 +x_0=100000 +y_0=200000
0dE 0dN

$ echo 0 0 | bin/proj +proj=wink2 +x_0=100000 +y_0=200000 | bin/proj -I +proj=wink2 +x_0=100000 +y_0=200000
0dE 0dN

[jjimenezshaw]

$ echo 0 0 | bin/proj +proj=adams_ws2 +x_0=100000 +y_0=200000 | bin/proj -I +proj=adams_ws2 +x_0=100000 +y_0=200000

Should it be this to change around the y=0 once applied the false northing?
echo 300000 200000 | bin/proj +proj=adams_ws2 +x_0=100000 +y_0=200000

[rouault]

Should it be this to change around the y=0 once applied the false northing?
echo 300000 200000 | bin/proj +proj=adams_ws2 +x_0=100000 +y_0=200000

hum, you meant with the -I flag right?

Wrks fine:

$ echo 300000 200000 | bin/proj -d 8 -I +proj=adams_ws2 +x_0=100000 +y_0=200000
3.59296648 0.00000000

$ echo 3.59296648 0.00000000 | bin/proj -d 8 +proj=adams_ws2 +x_0=100000 +y_0=200000
300000.00005671 200000.00000000