--- /dev/null
+## Copyright (C) 2004 Andrew Collier <abcollier@users.sourceforge.net>
+##
+## This program is free software; it is distributed in the hope that it
+## will be useful, but WITHOUT ANY WARRANTY; without even the implied
+## warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
+## the GNU General Public License for more details.
+##
+## You should have received a copy of the GNU General Public License
+## along with this file; see the file COPYING. If not, see
+## <http://www.gnu.org/licenses/>.
+
+## -*- texinfo -*-
+## @deftypefn {Function File} {} @var{az} = azimuth(@var{lat1},@var{lon1},@var{lat2},@var{lon2})
+## @deftypefnx {Function File} {} @var{az} = azimuth(@var{lat1},@var{lon1},@var{lat2},@var{lon2},@var{units})
+## @deftypefnx {Function File} {} @var{az} = azimuth(@var{pt1}, @var{pt2})
+## @deftypefnx {Function File} {} @var{az} = azimuth(@var{pt1}, @var{pt2},@var{units})
+##
+## Calculates the great circle azimuth from a point 1 to a point 2.
+## The latitude and longitude of these two points can either be given
+## independently or as columns of the matrices @var{pt1} and @var{pt2} in
+## the form [latitude longitude].
+##
+## The units for the input coordinates and output angles can be
+## "degrees" (the default) or "radians".
+##
+## @example
+## >> azimuth([10,10], [10,40])
+## ans = 87.336
+## >> azimuth([0,10], [0,40])
+## ans = 90
+## >> azimuth(pi/4,0,pi/4,-pi/2,"radians")
+## ans = 5.3279
+## @end example
+##
+## @seealso{elevation,distance}
+## @end deftypefn
+
+## Author: Andrew Collier <abcollier@users.sourceforge.net>
+## Adapted-by: Alexander Barth <abarth93@users.sourceforge.net>
+
+## Uses "four-parts" formula.
+
+function az = azimuth(varargin)
+ ## default units are degrees
+
+ units = "degrees";
+
+ [reg,prop] = parseparams(varargin);
+
+ if length(reg) == 2
+ pt1 = reg{1};
+ pt2 = reg{2};
+
+ a = pt1(:,1);
+ b = pt2(:,1);
+ C = pt2(:,2) - pt1(:,2);
+ elseif length(reg) == 4
+ a = reg{1};
+ b = reg{3};
+ C = reg{4} - reg{2};
+ else
+ error("Wrong number of type of arguments");
+ end
+
+ if length(prop) == 1
+ units = prop{1};
+
+ if (~strcmp(units,"degrees") & ~strcmp(units,"radians"))
+ error("Only degrees and radians are allowed as units");
+ end
+ elseif length(prop) > 1
+ error("Wrong number of type of arguments");
+ end
+
+ if (strcmp(units,"degrees"))
+ a = deg2rad(a);
+ b = deg2rad(b);
+ C = deg2rad(C);
+ end
+
+ az = atan2(sin(C) , cos(a) .* tan(b) - sin(a) .* cos(C) );
+
+ ## bring the angle in the interval [0 2*pi[
+
+ az = mod(az,2*pi);
+
+ ## convert to degrees if desired
+
+ if (strcmp(units,"degrees"))
+ az = rad2deg(az);
+ end
+endfunction
+
+## http://www.mathworks.com/access/helpdesk/help/toolbox/map/azimuth.shtml