[Proj] Problems with Pittman geodesic??

[Gerald I. Evenden]

While checking out the accuracy of Vincenty vs. Pittman
I was fairly consistently getting agreement to micron or
better.

BUT not always!!!

I would appreciate anyone who has a Pittman geodesic routine
to test the following inverse (WGS84 ellipsoid):

point 1 at 0 lat, 0 lon and point 2 at 45N 90E.

With my version of Pittman I get a distance of 9993541.5348708
AND I get the same distance while changing the longitude of the
second point from about 89.6 to a hair over 90.

At 0,0/45,89.5:
Pittman: 9970963.0100082
Vincenty:9970963.01000801

At 0,0/45,89.6
Pittman: 9993541.5348708
Vincenty:9978847.65947167

Pittman remained constant in this longitude interval

At 0,0/45,90
Pittman:  9993541.5348708
Vincenty:10010386.3610382

Between 90.0000001 and 90.000001 Pittman finally came back
into near agreement with Vincenty.

Note: I did nothing to the Pittman FORTRAN loaned from Mugnier
other than compile it with gfortran and link to a C driver.

-- 
The whole religious complexion of the modern world is due
to the absence from Jerusalem of a lunatic asylum.
-- Havelock Ellis (1859-1939) British psychologist