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1 ## Copyright (C) 2001, 2003, 2004, 2005, 2006, 2007, 2008 Paul Kienzle |
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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{s1}, @var{s2}, @dots{}, @var{sN}] =} ind2sub (@var{dims}, @var{ind}) |
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21 ## Convert a linear index into subscripts. |
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22 ## |
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23 ## The following example shows how to convert the linear index @code{8} |
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24 ## in a 3-by-3 matrix into a subscript. The matrix is linearly indexed |
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25 ## moving from one column to next, filling up all rows in each column. |
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26 ## @example |
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27 ## [r, c] = ind2sub ([3, 3], 8) |
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28 ## @result{} r = 2 |
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29 ## c = 3 |
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30 ## @end example |
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31 ## @seealso{sub2ind} |
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32 ## @end deftypefn |
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33 |
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34 ## Author: Paul Kienzle <pkienzle@kienzle.powernet.co.uk> |
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35 ## Adapted-by: jwe |
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36 |
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37 function varargout = ind2sub (dims, ind) |
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38 |
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39 if (nargin == 2) |
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40 if (isvector (dims) && all (round (dims) == dims)) |
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41 if (isnumeric (ind) && all (round (ind) == ind)) |
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42 ntot = prod (dims); |
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43 if (all (ind > 0 & ind <= ntot)) |
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44 nd = length (dims); |
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45 if (nargout > 0) |
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46 vlen = nargout; |
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47 else |
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48 vlen = 1; |
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49 endif |
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50 if (nd > vlen); |
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51 dims(vlen) = prod (dims(vlen:nd)); |
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52 dims(vlen+1:nd) = []; |
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53 endif |
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54 nd = length (dims); |
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55 scale = [1; cumprod(dims(:))]; |
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56 for i = nd:-1:2 |
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57 k = (ind >= scale(i)); |
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58 r = ones (size (ind)); |
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59 t = zeros (size (ind)); |
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60 t(k) = floor ((ind(k) - 1) / scale(i)); |
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61 r(k) = t(k) + 1; |
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62 varargout{i} = r; |
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63 ind(k) -= t(k) * scale(i); |
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64 endfor |
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65 varargout{1} = ind; |
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66 for i = nd+1:vlen |
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67 varargout{i} = ones (size (ind)); |
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68 endfor |
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69 else |
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70 error ("ind2sub: index out of range"); |
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71 endif |
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72 else |
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73 error ("ind2sub: expecting integer-valued index argument"); |
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74 endif |
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75 else |
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76 error ("ind2sub: expecting dims to be an integer vector"); |
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77 endif |
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78 else |
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79 print_usage (); |
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80 endif |
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81 |
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82 |
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83 endfunction |
