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1 ## Copyright (C) 1996, 1997 John W. Eaton |
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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} {} prepad (@var{x}, @var{l}, @var{c}) |
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22 ## @deftypefnx {Function File} {} postpad (@var{x}, @var{l}, @var{c}) |
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23 ## |
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24 ## Prepends (appends) the scalar value @var{c} to the vector @var{x} |
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25 ## until it is of length @var{l}. If the third argument is not |
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26 ## supplied, a value of 0 is used. |
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27 ## |
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28 ## If @code{length (@var{x}) > @var{l}}, elements from the beginning (end) of |
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29 ## @var{x} are removed until a vector of length @var{l} is obtained. |
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30 ## |
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31 ## If @var{x} is a matrix, elements are prepended or removed from each row. |
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32 ## @end deftypefn |
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33 |
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34 ## Author: Tony Richardson <arichard@stark.cc.oh.us> |
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35 ## Created: June 1994 |
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36 |
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37 function y = prepad (x, l, c) |
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38 |
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39 if (nargin == 2) |
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40 c = 0; |
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41 elseif (nargin < 2 || nargin > 3) |
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42 usage ("prepad (x, l) or prepad (x, l, c)"); |
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43 endif |
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44 |
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45 if (! ismatrix (x)) |
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46 error ("first argument must be a vector or matrix"); |
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47 elseif (! isscalar (l)) |
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48 error ("second argument must be a scaler"); |
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49 endif |
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50 |
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51 if (l < 0) |
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52 error ("second argument must be non-negative"); |
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53 endif |
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54 |
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55 [nr, nc] = size (x); |
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56 if (nr == 1) |
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57 if (nc >= l) |
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58 y = x(nc-l+1:nc); |
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59 else |
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60 y = [c*ones(1,l-nc), x]; |
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61 endif |
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62 else |
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63 if (nr >= l) |
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64 y = x(nr-l+1:nr,:); |
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65 else |
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66 y = [c*ones(l-nr,nc); x]; |
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67 endif |
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68 endif |
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69 |
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70 endfunction |
