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1 ## Copyright (C) 2007 Michael Goffioul |
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2 ## |
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3 ## This program is free software; you can redistribute it and/or modify |
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4 ## it under the terms of the GNU General Public License as published by |
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5 ## the Free Software Foundation; either version 2 of the License, or |
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6 ## (at your option) any later version. |
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7 ## |
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8 ## This program is distributed in the hope that it will be useful, |
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9 ## but WITHOUT ANY WARRANTY; without even the implied warranty of |
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10 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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11 ## GNU General Public License for more details. |
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12 ## |
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13 ## You should have received a copy of the GNU General Public License |
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14 ## along with this program; if not, write to the Free Software |
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15 ## Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA |
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16 ## 02110-1301 USA |
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17 |
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18 ## -*- texinfo -*- |
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19 ## @deftypefn {Function File} {[@var{x}, @var{y}, @var{z}] =} sphere (@var{n}) |
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20 ## @deftypefnx {Function File} {} sphere (@var{h}, @dots{}) |
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21 ## Generates three matrices in @code{meshgrid} format, such that |
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22 ## @code{surf (@var{x}, @var{y}, @var{z})} generates a unit sphere. |
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23 ## The matrices of @code{@var{n}+1}-by-@code{@var{n}+1}. If @var{n} is |
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24 ## omitted then a default value of 20 is assumed. |
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25 ## |
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26 ## Called with no return arguments, @code{sphere} call directly |
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27 ## @code{surf (@var{x}, @var{y}, @var{z})}. If an axes handle is passed |
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28 ## as the first argument, the the surface is plotted to this set of axes. |
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29 ## @seealso{peaks} |
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30 ## @end deftypefn |
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31 |
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32 function [xx, yy, zz] = sphere (h, n) |
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33 |
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34 have_h = false; |
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35 if (nargin > 1 && isscalar (h) && ishandle (h)) |
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36 if (! strcmp (get (h, "type"), "axes")) |
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37 error ("sphere: expecting first argument to be an axes object"); |
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38 endif |
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39 if (nargin == 1) |
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40 n = 20; |
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41 endif |
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42 have_h = true; |
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43 elseif (nargin == 1) |
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44 n = h; |
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45 else |
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46 n = 20; |
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47 endif |
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48 |
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49 theta = linspace (0, 2*pi, n+1); |
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50 phi = linspace (-pi/2, pi/2, n+1); |
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51 [theta,phi] = meshgrid (theta, phi); |
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52 |
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53 x = cos (phi) .* cos (theta); |
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54 y = cos (phi) .* sin (theta); |
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55 z = sin (phi); |
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56 |
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57 if (nargout > 0) |
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58 xx = x; |
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59 yy = y; |
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60 zz = z; |
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61 else |
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62 if (have_h) |
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63 oldh = gca (); |
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64 unwind_protect |
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65 axes (h); |
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66 surf (x, y, z); |
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67 unwind_protect_cleanup |
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68 axes (oldh); |
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69 end_unwind_protect |
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70 else |
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71 surf (x, y, z); |
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72 endif |
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73 endif |
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74 |
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75 endfunction |
