Mercurial > hg > octave-nkf
annotate scripts/geometry/convhull.m @ 12575:d0b799dafede
Grammarcheck files for 3.4.1 release.
| author | Rik <octave@nomad.inbox5.com> |
|---|---|
| date | Mon, 04 Apr 2011 15:33:46 -0700 |
| parents | c792872f8942 |
| children | 7ff0bdc3dc4c |
| rev | line source |
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| 11523 | 1 ## Copyright (C) 2000-2011 Kai Habel |
| 6823 | 2 ## |
| 3 ## This file is part of Octave. | |
| 4 ## | |
| 5 ## Octave is free software; you can redistribute it and/or modify it | |
| 6 ## under the terms of the GNU General Public License as published by | |
| 7016 | 7 ## the Free Software Foundation; either version 3 of the License, or (at |
| 8 ## your option) any later version. | |
| 6823 | 9 ## |
| 10 ## Octave is distributed in the hope that it will be useful, but | |
| 11 ## WITHOUT ANY WARRANTY; without even the implied warranty of | |
| 12 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
| 13 ## General Public License for more details. | |
| 14 ## | |
| 15 ## You should have received a copy of the GNU General Public License | |
| 7016 | 16 ## along with Octave; see the file COPYING. If not, see |
| 17 ## <http://www.gnu.org/licenses/>. | |
| 6823 | 18 |
| 19 ## -*- texinfo -*- | |
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20 ## @deftypefn {Function File} {@var{H} =} convhull (@var{x}, @var{y}) |
| 6846 | 21 ## @deftypefnx {Function File} {@var{H} =} convhull (@var{x}, @var{y}, @var{opt}) |
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Grammarcheck files for 3.4.1 release.
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22 ## Return the index vector to the points of the enclosing convex hull. The |
| 6823 | 23 ## data points are defined by the x and y vectors. |
| 24 ## | |
| 25 ## A third optional argument, which must be a string, contains extra options | |
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26 ## passed to the underlying qhull command. See the documentation for the |
| 6823 | 27 ## Qhull library for details. |
| 28 ## | |
| 29 ## @seealso{delaunay, convhulln} | |
| 30 ## @end deftypefn | |
| 31 | |
| 6826 | 32 ## Author: Kai Habel <kai.habel@gmx.de> |
| 6823 | 33 |
| 6826 | 34 function H = convhull (x, y, opt) |
| 6823 | 35 |
| 6826 | 36 if (nargin != 2 && nargin != 3) |
| 6823 | 37 print_usage (); |
| 38 endif | |
| 39 | |
| 6826 | 40 if (isvector (x) && isvector (y) && length (x) == length (y)) |
| 6823 | 41 if (nargin == 2) |
| 6826 | 42 i = convhulln ([x(:), y(:)]); |
| 43 elseif (ischar (opt) || iscell (opt)) | |
| 44 i = convhulln ([x(:), y(:)], opt); | |
| 6823 | 45 else |
| 6826 | 46 error ("convhull: third argument must be a string or cell array of strings"); |
| 6823 | 47 endif |
| 48 else | |
| 6826 | 49 error ("convhull: first two input arguments must be vectors of same size"); |
| 6823 | 50 endif |
| 51 | |
| 6826 | 52 n = rows (i); |
| 6823 | 53 i = i'(:); |
| 6826 | 54 H = zeros (n + 1, 1); |
| 6823 | 55 |
| 56 H(1) = i(1); | |
| 57 next_i = i(2); | |
| 58 i(2) = 0; | |
| 59 for k = 2:n | |
| 60 next_idx = find (i == next_i); | |
| 61 | |
| 62 if (rem (next_idx, 2) == 0) | |
| 63 H(k) = i(next_idx); | |
| 64 next_i = i(next_idx - 1); | |
| 65 i(next_idx - 1) = 0; | |
| 66 else | |
| 67 H(k) = i(next_idx); | |
| 68 next_i = i(next_idx + 1); | |
| 69 i(next_idx + 1) = 0; | |
| 70 endif | |
| 71 endfor | |
| 72 | |
| 73 H(n + 1) = H(1); | |
| 74 endfunction | |
| 75 | |
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76 %!testif HAVE_QHULL |
| 6823 | 77 %! x = -3:0.5:3; |
| 78 %! y = abs (sin (x)); | |
| 79 %! assert (convhull (x, y, {"s","Qci","Tcv","Pp"}), [1;7;13;12;11;10;4;3;2;1]) | |
| 80 | |
| 81 %!demo | |
| 82 %! x = -3:0.05:3; | |
| 83 %! y = abs (sin (x)); | |
| 84 %! k = convhull (x, y); | |
| 85 %! plot (x(k),y(k),'r-',x,y,'b+'); | |
| 86 %! axis ([-3.05, 3.05, -0.05, 1.05]); |