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view main/geometry/convhull.m @ 0:6b33357c7561 octave-forge
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author | pkienzle |
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date | Wed, 10 Oct 2001 19:54:49 +0000 |
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children | 188590228c32 |
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## Copyright (C) 2000 Kai Habel ## ## This program is free software; you can redistribute it and/or modify ## it under the terms of the GNU General Public License as published by ## the Free Software Foundation; either version 2 of the License, or ## (at your option) any later version. ## ## This program 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 program; if not, write to the Free Software ## Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA ## -*- texinfo -*- ## @deftypefn {Loadable Function} {@var{H} =} convhull (@var{x}, @var{y}) ## returns the index vector to the points of the enclosing convex hull ## @end deftypefn ## @seealso{delaunay, convhulln} ## Author: Kai Habel <kai.habel@gmx.de> function H = convhull (x,y) if (nargin != 2) usage ("convhull(x,y)"); endif if (is_vector(x) && is_vector(y) && (length(x) == length(y)) ) i = convhulln([x(:), y(:)]); endif n = rows(i); i=i'(:); H = zeros(n + 1,1); H(1) = i(1); next_i = i(2); i(2) = 0; for k = 2:n next_idx = find (i == next_i); if (rem (next_idx, 2) == 0) H(k) = i(next_idx); next_i = i(next_idx - 1); i(next_idx - 1) = 0; else H(k) = i(next_idx); next_i = i(next_idx + 1); i(next_idx + 1) = 0; endif endfor H(n+1)=H(1); endfunction