Add a useful package (from Source forge) for octave

[CreaPhase.git] / octave_packages / mapping-1.0.7 / distance.m

diff --git a/octave_packages/mapping-1.0.7/distance.m b/octave_packages/mapping-1.0.7/distance.m
new file mode 100644 (file)
index 0000000..8b726ae
--- /dev/null
+++ b/octave_packages/mapping-1.0.7/distance.m
@@ -0,0 +1,44 @@
+## 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{dist} = distance(@var{pt1}, @var{pt2})
+##
+## Calculates the distance (in degrees) between @var{pt1} and @var{pt2}.
+##
+## @var{pt1} and @var{pt2} are two-column matrices of the form [latitude longitude].
+##
+## @example
+## >> distance([37,-76], [37,-9]) 
+## ans = 52.309
+## >> distance([37,-76], [67,-76])
+## ans = 30.000
+## @end example
+##
+## @seealso{azimuth,elevation}
+## @end deftypefn
+
+## Author: Andrew Collier <abcollier@users.sourceforge.net>
+
+## Uses "cosine formula".
+
+function dist = distance(pt1, pt2)
+  pt1 = deg2rad(pt1);
+  pt2 = deg2rad(pt2);
+
+  c = pi / 2 - pt1(1);
+  b = pi / 2 - pt2(1);
+  A = pt2(2) - pt1(2);
+
+  dist = rad2deg(acos(cos(b) * cos(c) + sin(b) * sin(c) * cos(A)));
+endfunction
+
+## http://www.mathworks.com/access/helpdesk/help/toolbox/map/distance.shtml