Mercurial > forge

comparison main/geometry/convhull.m @ 0:6b33357c7561 octave-forge

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
Initial revision
author pkienzle
date Wed, 10 Oct 2001 19:54:49 +0000
parents
children 188590228c32
comparison
equal deleted inserted replaced
-1:000000000000 0:6b33357c7561
1 ## Copyright (C) 2000 Kai Habel
2 ##
3 ## This program is free software; you can redistribute it and/or modify
4 ## it under the terms of the GNU General Public License as published by
5 ## the Free Software Foundation; either version 2 of the License, or
6 ## (at your option) any later version.
7 ##
8 ## This program is distributed in the hope that it will be useful,
9 ## but WITHOUT ANY WARRANTY; without even the implied warranty of
10 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 ## GNU General Public License for more details.
12 ##
13 ## You should have received a copy of the GNU General Public License
14 ## along with this program; if not, write to the Free Software
15 ## Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
16
17 ## -*- texinfo -*-
18 ## @deftypefn {Loadable Function} {@var{H} =} convhull (@var{x}, @var{y})
19 ## returns the index vector to the points of the enclosing convex hull
20 ## @end deftypefn
21 ## @seealso{delaunay, convhulln}
22
23 ## Author: Kai Habel <kai.habel@gmx.de>
24
25 function H = convhull (x,y)
26
27 if (nargin != 2)
28 usage ("convhull(x,y)");
29 endif
30
31 if (is_vector(x) && is_vector(y) && (length(x) == length(y)) )
32 i = convhulln([x(:), y(:)]);
33 endif
34
35 n = rows(i);
36 i=i'(:);
37 H = zeros(n + 1,1);
38
39 H(1) = i(1);
40 next_i = i(2);
41 i(2) = 0;
42 for k = 2:n
43 next_idx = find (i == next_i);
44
45 if (rem (next_idx, 2) == 0)
46 H(k) = i(next_idx);
47 next_i = i(next_idx - 1);
48 i(next_idx - 1) = 0;
49 else
50 H(k) = i(next_idx);
51 next_i = i(next_idx + 1);
52 i(next_idx + 1) = 0;
53 endif
54 endfor
55
56 H(n+1)=H(1);
57 endfunction