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1 ## Copyright (C) 1995, 1996 Kurt Hornik |
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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} {} shift (@var{x}, @var{b}) |
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21 ## @deftypefnx {Function File} {} shift (@var{x}, @var{b}, @var{dim}) |
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22 ## If @var{x} is a vector, perform a circular shift of length @var{b} of |
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23 ## the elements of @var{x}. |
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24 ## |
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25 ## If @var{x} is a matrix, do the same for each column of @var{x}. |
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26 ## If the optional @var{dim} argument is given, operate along this |
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27 ## dimension |
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28 ## @end deftypefn |
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29 |
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30 ## Author: AW <Andreas.Weingessel@ci.tuwien.ac.at> |
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31 ## Created: 14 September 1994 |
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32 ## Adapted-By: jwe |
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33 |
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34 function y = shift (x, b, dim) |
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35 |
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36 if (nargin != 2 && nargin != 3) |
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37 print_usage (); |
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38 endif |
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39 |
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40 if (! (isscalar (b) && b == round (b))) |
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41 error ("shift: b must be an integer"); |
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42 endif |
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43 |
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44 nd = ndims (x); |
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45 sz = size (x); |
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46 |
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47 if (nargin == 3) |
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48 if (! (isscalar (dim) && dim == round (dim)) && dim > 0 && |
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49 dim < (nd + 1)) |
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50 error ("shift: dim must be an integer and valid dimension"); |
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51 endif |
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52 else |
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53 ## Find the first non-singleton dimension |
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54 dim = 1; |
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55 while (dim < nd + 1 && sz (dim) == 1) |
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56 dim = dim + 1; |
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57 endwhile |
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58 if (dim > nd) |
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59 dim = 1; |
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60 endif |
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61 endif |
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62 |
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63 if (numel (x) < 1) |
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64 error ("shift: x must not be empty"); |
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65 endif |
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66 |
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67 d = sz (dim); |
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68 |
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69 idx = cell (); |
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70 for i = 1:nd |
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71 idx {i} = 1:sz(i); |
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72 endfor |
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73 if (b >= 0) |
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74 b = rem (b, d); |
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75 idx {dim} = [d-b+1:d, 1:d-b]; |
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76 elseif (b < 0) |
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77 b = rem (abs (b), d); |
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78 idx {dim} = [b+1:d, 1:b]; |
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79 endif |
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80 y = x (idx {:}); |
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81 |
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82 |
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83 endfunction |
