[Proj] Test points double stereographic projection

[OvV_HN]

As promised, and a bit sooner than expected (if at all):
pretty good test points for the double stereographic projection, sterea in 
libproj/proj.

Double stereographic projection
======================

Examples.
My values, compared with (near) official sources.
My values are calculated with a reincarnation of libprojs sterea.

Prince Edward Island
---------------------
Source:
A manual for geodetic coordinate transformations in the maritime provinces, 
D.B. Thomson, E.J. Krakiwsky, R.R. Steeves, Technical Report No. 48, July 
1977, Department of Geodesy and Geomatics Engineering, University of New 
Brunswick, Canada.
http://gge.unb.ca/Pubs/TR48.pdf

lat = 46d 42m 28.147s; lon = -64d 29m 34.014s;
lat0 = 47.25d; lon0 = -63;
x0 = 7e5; y0 = 4e5;
k0 = 0.999912;
Clarke 1866 ellipsoid
->
x = 585855.4464; source: 585855.446 m
y = 340817.7602; source: 340817.760 m


Rijksdriehoeksstelsel Nederland (The Netherlands)
-------------------------------
Source:
"Coördinatentransformator" by Ed Stevenhagen.
https://rdinfo.kadaster.nl/

x = 100000; y = 400000;
lat0 = 52d 9m 22.178s; lon0 = 5d 23m 15.500s;
x0 = 155000.00; y0 = 463000.00;
k0 = 0.9999079;
Bessel 1841 ellipsoid
->
lat = 51d 35m 13.69685s;  source: 51d 35m 13.7s;
lon =  4d 35m 38.106473s; source:  4d 35m 38.1s;
This is without grid interpolation.


Romanian Stereo-70
-------------------
Source:
The Official Viteaz Page
Transformation between the Transylvanian grid coordinates.
Gábor Timár, Space Research Group, Dept. of Geophysics, Eötvös University of 
Budapest, Hungary.
Calculator: viteaz.xls
http://sas2.elte.hu/tg/viteaz_en.htm

x = 430869.000; y = 482668.000;
lat0 = 46; lon0 = 25;
x0 = 5e5; y0 = 5e5;
k0 = 0.99975;
Krasowski 1940 ellipsoid
->
lat = 45d 50m 26.01090s; source: 45d 50m 26.01s
lon = 24d 06m 35.64460s; source: 24d  6m 35.64s


Yours,

Oscar van Vlijmen