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1 ## Copyright (C) 1995, 1996, 1999, 2000, 2002, 2003, 2004, 2005, 2006, |
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2 ## 2007 Kurt Hornik |
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3 ## |
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4 ## This file is part of Octave. |
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5 ## |
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6 ## Octave is free software; you can redistribute it and/or modify it |
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7 ## under the terms of the GNU General Public License as published by |
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8 ## the Free Software Foundation; either version 3 of the License, or (at |
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9 ## your option) any later version. |
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10 ## |
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11 ## Octave is distributed in the hope that it will be useful, but |
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12 ## WITHOUT ANY WARRANTY; without even the implied warranty of |
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13 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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14 ## General Public License for more details. |
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15 ## |
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16 ## You should have received a copy of the GNU General Public License |
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17 ## along with Octave; see the file COPYING. If not, see |
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18 ## <http://www.gnu.org/licenses/>. |
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19 |
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20 ## -*- texinfo -*- |
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21 ## @deftypefn {Function File} {} shift (@var{x}, @var{b}) |
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22 ## @deftypefnx {Function File} {} shift (@var{x}, @var{b}, @var{dim}) |
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23 ## If @var{x} is a vector, perform a circular shift of length @var{b} of |
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24 ## the elements of @var{x}. |
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25 ## |
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26 ## If @var{x} is a matrix, do the same for each column of @var{x}. |
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27 ## If the optional @var{dim} argument is given, operate along this |
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28 ## dimension |
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29 ## @end deftypefn |
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30 |
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31 ## Author: AW <Andreas.Weingessel@ci.tuwien.ac.at> |
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32 ## Created: 14 September 1994 |
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33 ## Adapted-By: jwe |
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34 |
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35 function y = shift (x, b, dim) |
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36 |
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37 if (nargin != 2 && nargin != 3) |
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38 print_usage (); |
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39 endif |
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40 |
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41 if (! (isscalar (b) && b == round (b))) |
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42 error ("shift: b must be an integer"); |
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43 endif |
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44 |
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45 nd = ndims (x); |
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46 sz = size (x); |
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47 |
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48 if (nargin == 3) |
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49 if (! (isscalar (dim) && dim == round (dim)) && dim > 0 && |
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50 dim < (nd + 1)) |
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51 error ("shift: dim must be an integer and valid dimension"); |
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52 endif |
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53 else |
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54 ## Find the first non-singleton dimension |
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55 dim = 1; |
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56 while (dim < nd + 1 && sz (dim) == 1) |
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57 dim = dim + 1; |
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58 endwhile |
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59 if (dim > nd) |
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60 dim = 1; |
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61 endif |
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62 endif |
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63 |
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64 if (numel (x) < 1) |
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65 error ("shift: x must not be empty"); |
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66 endif |
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67 |
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68 d = sz (dim); |
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69 |
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70 idx = cell (); |
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71 for i = 1:nd |
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72 idx{i} = 1:sz(i); |
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73 endfor |
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74 if (b >= 0) |
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75 b = rem (b, d); |
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76 idx{dim} = [d-b+1:d, 1:d-b]; |
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77 elseif (b < 0) |
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78 b = rem (abs (b), d); |
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79 idx{dim} = [b+1:d, 1:b]; |
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80 endif |
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81 y = x(idx{:}); |
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82 |
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83 endfunction |
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84 |
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85 %!test |
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86 %! a = [1, 2, 3]; |
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87 %! b = [4, 5, 6]; |
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88 %! c = [7, 8, 9]; |
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89 %! |
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90 %! r = [a, b, c]; |
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91 %! m = [a; b; c]; |
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92 %! |
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93 %! assert((shift (r, 3) == [c, a, b] |
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94 %! && shift (r, -6) == [c, a, b] |
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95 %! && shift (r, -3) == [b, c, a] |
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96 %! && shift (m, 1) == [c; a; b] |
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97 %! && shift (m, -2) == [c; a; b])); |
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98 |
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99 %!error shift (); |
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100 |
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101 %!error shift (1, 2, 3, 4); |
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102 |
