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1 ## Copyright (C) 1995, 1996 Kurt Hornik |
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2 ## |
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3 ## This program is free software; you can redistribute it and/or modify |
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4 ## it under the terms of the GNU General Public License as published by |
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5 ## the Free Software Foundation; either version 2, or (at your option) |
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6 ## any later version. |
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7 ## |
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8 ## This program is distributed in the hope that it will be useful, but |
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9 ## WITHOUT ANY WARRANTY; without even the implied warranty of |
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10 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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11 ## General Public License for more details. |
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12 ## |
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13 ## You should have received a copy of the GNU General Public License |
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14 ## along with this file. If not, write to the Free Software Foundation, |
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15 ## 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
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16 |
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17 ## -*- texinfo -*- |
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18 ## @deftypefn {Function File} {} shift (@var{x}, @var{b}) |
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19 ## If @var{x} is a vector, perform a circular shift of length @var{b} of |
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20 ## the elements of @var{x}. |
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21 ## |
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22 ## If @var{x} is a matrix, do the same for each column of @var{x}. |
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23 ## @end deftypefn |
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24 |
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25 ## Author: AW <Andreas.Weingessel@ci.tuwien.ac.at> |
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26 ## Created: 14 September 1994 |
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27 ## Adapted-By: jwe |
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28 |
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29 function y = shift (x, b) |
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30 |
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31 if (nargin != 2) |
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32 usage ("shift (X, b)"); |
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33 endif |
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34 |
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35 [nr, nc] = size (x); |
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36 |
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37 if (nr == 0 || nc == 0) |
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38 error ("shift: x must not be empty"); |
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39 elseif (nr == 1) |
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40 x = x.'; |
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41 nr = nc; |
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42 nc = 0; |
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43 endif |
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44 |
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45 if (! (is_scalar (b) && b == round (b))) |
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46 error ("shift: b must be an integer"); |
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47 endif |
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48 |
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49 if (b >= 0) |
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50 b = rem (b, nr); |
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51 t1 = x (nr-b+1:nr, :); |
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52 t2 = x (1:nr-b, :); |
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53 y = [t1; t2]; |
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54 elseif (b < 0) |
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55 b = rem (abs (b), nr); |
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56 t1 = x (b+1:nr, :); |
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57 t2 = x (1:b, :); |
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58 y = [t1; t2]; |
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59 endif |
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60 |
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61 if (nc == 0) |
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62 y = reshape (y, 1, nr); |
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63 endif |
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64 |
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65 endfunction |
