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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 ## usage: y = shift (x, b) |
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18 ## |
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19 ## If x is a vector, perform a circular shift of length b of the |
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20 ## elements of x. |
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21 ## |
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22 ## If x is a matrix, do the same for each column of x. |
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23 |
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24 ## Author: AW <Andreas.Weingessel@ci.tuwien.ac.at> |
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25 ## Created: 14 September 1994 |
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26 ## Adapted-By: jwe |
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27 |
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28 function y = shift (x, b) |
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29 |
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30 if (nargin != 2) |
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31 error ("usage: shift (X, b)"); |
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32 endif |
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33 |
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34 [nr nc] = size (x); |
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35 |
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36 if (nr == 0 || nc == 0) |
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37 error ("shift: x must not be empty"); |
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38 elseif (nr == 1) |
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39 x = x.'; |
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40 nr = nc; |
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41 nc = 0; |
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42 endif |
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43 |
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44 if (! (is_scalar (b) && b == round (b))) |
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45 error ("shift: b must be an integer"); |
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46 endif |
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47 |
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48 if (b >= 0) |
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49 b = rem (b, nr); |
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50 y = [x (nr - b + 1 : nr, :); x (1 : nr - b, :)]; |
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51 elseif (b < 0) |
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52 b = rem (abs (b), nr); |
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53 y = [x (b + 1 : nr, :); x (1 : b, :)]; |
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54 endif |
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55 |
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56 if (nc == 0) |
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57 y = reshape (y, 1, nr); |
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58 endif |
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59 |
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60 endfunction |
