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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 ## usage: conv (a, b) |
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21 ## |
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22 ## Convolve two vectors. |
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23 ## |
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24 ## y = conv (a, b) returns a vector of length equal to length (a) + |
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25 ## length (b) -1. |
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26 ## |
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27 ## If a and b are polynomial coefficient vectors, conv returns the |
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28 ## coefficients of the product polynomial. |
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29 ## |
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30 ## SEE ALSO: deconv, poly, roots, residue, polyval, polyderiv, polyinteg |
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31 |
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32 ## Author: Tony Richardson <amr@mpl.ucsd.edu> |
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33 ## Created: June 1994 |
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34 ## Adapted-By: jwe |
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35 |
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36 function y = conv (a, b) |
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37 |
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38 if (nargin != 2) |
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39 usage ("conv(a, b)"); |
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40 endif |
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41 |
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42 if (! (is_vector (a) && is_vector (b))) |
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43 error("conv: both arguments must be vectors"); |
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44 endif |
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45 |
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46 la = length (a); |
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47 lb = length (b); |
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48 |
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49 ly = la + lb - 1; |
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50 |
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51 ## Ensure that both vectors are row vectors. |
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52 if (rows (a) > 1) |
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53 a = reshape (a, 1, la); |
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54 endif |
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55 if (rows (b) > 1) |
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56 b = reshape (b, 1, lb); |
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57 endif |
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58 |
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59 ## Use the shortest vector as the coefficent vector to filter. |
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60 if (la < lb) |
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61 if (ly > lb) |
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62 x = [b, (zeros (1, ly - lb))]; |
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63 else |
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64 x = b; |
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65 endif |
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66 y = filter (a, 1, x); |
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67 else |
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68 if(ly > la) |
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69 x = [a, (zeros (1, ly - la))]; |
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70 else |
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71 x = a; |
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72 endif |
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73 y = filter (b, 1, x); |
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74 endif |
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75 |
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76 endfunction |
