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1 ## Copyright (C) 2007 Sylvain Pelissier |
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2 ## |
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3 ## This file is part of Octave. |
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4 ## |
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5 ## Octave is free software; you can redistribute it and/or modify it |
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6 ## under the terms of the GNU General Public License as published by |
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7 ## the Free Software Foundation; either version 3 of the License, or (at |
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8 ## your option) any later version. |
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9 ## |
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10 ## Octave is distributed in the hope that it will be useful, but |
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11 ## WITHOUT ANY WARRANTY; without even the implied warranty of |
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12 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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13 ## General Public License for more details. |
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14 ## |
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15 ## You should have received a copy of the GNU General Public License |
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16 ## along with Octave; see the file COPYING. If not, see |
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17 ## <http://www.gnu.org/licenses/>. |
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18 |
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19 ## -*- texinfo -*- |
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20 ## @deftypefn {Function File} {[@var{x}, @var{y}, @var{z}] =} ellipsoid (@var{xc},@var{yc}, @var{zc}, @var{xr}, @var{yr}, @var{zr}, @var{n}) |
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21 ## @deftypefnx {Function File} {} ellipsoid (@var{h}, @dots{}) |
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22 ## Generate three matrices in @code{meshgrid} format that define an |
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23 ## ellipsoid. Called with no return arguments, @code{ellipsoid} calls |
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24 ## directly @code{surf (@var{x}, @var{y}, @var{z})}. If an axes handle |
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25 ## is passed as the first argument, the the surface is plotted to this |
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26 ## set of axes. |
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27 ## @seealso{sphere} |
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28 ## @end deftypefn |
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29 |
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30 ## Author: Sylvain Pelissier <sylvain.pelissier@gmail.com> |
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31 |
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32 function [xx, yy, zz] = ellipsoid (varargin) |
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33 |
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34 [h, varargin, nargin] = __plt_get_axis_arg__ ((nargout > 0), "ellipsoid", |
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35 varargin{:}); |
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36 |
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37 if (nargin != 6 && nargin != 7) |
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38 print_usage (); |
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39 endif |
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40 |
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41 xc = varargin{1}; |
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42 yc = varargin{2}; |
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43 zc = varargin{3}; |
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44 xr = varargin{4}; |
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45 yr = varargin{5}; |
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46 zr = varargin{6}; |
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47 |
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48 if (nargin == 5) |
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49 n = 20; |
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50 else |
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51 n = varargin{7}; |
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52 endif |
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53 |
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54 theta = linspace (0, 2 * pi, n + 1); |
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55 phi = linspace (-pi / 2, pi / 2, n + 1); |
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56 [theta, phi] = meshgrid (theta, phi); |
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57 |
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58 x = xr .* cos (phi) .* cos (theta) + xc; |
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59 y = yr .* cos (phi) .* sin (theta) + yc; |
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60 z = zr .* sin (phi) + zc; |
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61 |
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62 if (nargout > 0) |
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63 xx = x; |
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64 yy = y; |
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65 zz = z; |
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66 else |
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67 surf (h, x, y, z); |
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68 endif |
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69 |
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70 endfunction |
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71 |
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72 %!demo |
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73 %! ellipsoid (0, 0, 1, 2, 3, 4, 20); |