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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 2, or (at your option) |
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8 ## 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, write to the Free |
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17 ## Software Foundation, 59 Temple Place - Suite 330, Boston, MA |
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18 ## 02111-1307, USA. |
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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 ## 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 ## @end deftypefn |
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27 |
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28 ## Author: AW <Andreas.Weingessel@ci.tuwien.ac.at> |
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29 ## Created: 14 September 1994 |
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30 ## Adapted-By: jwe |
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31 |
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32 function y = shift (x, b) |
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33 |
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34 if (nargin != 2) |
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35 usage ("shift (X, b)"); |
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36 endif |
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37 |
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38 [nr, nc] = size (x); |
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39 |
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40 if (nr == 0 || nc == 0) |
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41 error ("shift: x must not be empty"); |
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42 elseif (nr == 1) |
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43 x = x.'; |
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44 nr = nc; |
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45 nc = 0; |
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46 endif |
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47 |
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48 if (! (is_scalar (b) && b == round (b))) |
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49 error ("shift: b must be an integer"); |
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50 endif |
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51 |
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52 if (b >= 0) |
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53 b = rem (b, nr); |
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54 t1 = x (nr-b+1:nr, :); |
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55 t2 = x (1:nr-b, :); |
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56 y = [t1; t2]; |
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57 elseif (b < 0) |
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58 b = rem (abs (b), nr); |
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59 t1 = x (b+1:nr, :); |
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60 t2 = x (1:b, :); |
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61 y = [t1; t2]; |
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62 endif |
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63 |
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64 if (nc == 0) |
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65 y = reshape (y, 1, nr); |
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66 endif |
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67 |
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68 endfunction |
