[OSRS-PROJ] problem with azimuth and distance

[Pedro Morón Macías]

Here's a little problem I have with the PROJ4 library, and since I've
found no answer in the documentation nor in several sources, I'm trying
this list.

I have to determine latitude and longitude of a point given and initial
point latitude and longitude, and an azimuth and a distance from this
point.
I'm using the "geod" program to test the library and these are the
results:

csp1.pmm:~/csp98/swb/proj.4/src > geod +units=kmi +ellps=WGS84 <<EOF
> 80dN 10dE 90d 100
> EOF
79d51'53.25"N   19d27'54.76"E   -80d40'47.564"

In the example I want to determine the point at 90degrees azimuth and
100 nautic miles away from 80degrees North, 10degrees East.

The given azimuth equals to 90 degrees, then, why the resulting latitude
doesn't equal to 80 degrees North, like the starting point does?

Why the back azimuth doesn't equal to -90 degrees?


I'm sure this problem is not a bug of the PROJ4 library, and I want to
know where am I misusing the library...


Thanks a lot.




---------------------------------------------------------------
Pedro Moron Macias                         Ingeniero Industrial
SAINSEL Sistemas Navales, S.A.          Manuel Velasco Pando, 7
41007 SEVILLA - SPAIN                  mailto:pmoron at sainsel.es
Tel.:+34-954936401, Fax :+34-954936433, Home Tel.:+34-639349940
---------------------------------------------------------------
----------------------------------------
OSRS PRoject PROJ Discussion List
To Subscribe: send a message to majordomo at remotesensing.org with 'subscribe osrs-proj' in the body
To Unsubscribe: send a message to majordomo at remotesensing.org with 'unsubscribe osrs-proj' in the body
To Report Problems: send a message to owner-osrs-proj at remotesensing.org