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1 ### Copyright (C) 1996 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 function y = conv (a, b) |
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33 |
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34 ## Written by Tony Richardson (amr@mpl.ucsd.edu) June 1994. |
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35 |
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36 if (nargin != 2) |
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37 usage ("conv(a, b)"); |
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38 endif |
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39 |
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40 if (is_matrix (a) || is_matrix (b)) |
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41 error("conv: both arguments must be vectors"); |
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42 endif |
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43 |
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44 la = length (a); |
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45 lb = length (b); |
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46 |
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47 ly = la + lb - 1; |
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48 |
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49 ## Ensure that both vectors are row vectors. |
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50 if (rows (a) > 1) |
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51 a = reshape (a, 1, la); |
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52 endif |
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53 if (rows (b) > 1) |
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54 b = reshape (b, 1, lb); |
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55 endif |
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56 |
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57 ## Use the shortest vector as the coefficent vector to filter. |
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58 if (la < lb) |
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59 if (ly > lb) |
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60 x = [b, (zeros (1, ly - lb))]; |
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61 else |
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62 x = b; |
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63 endif |
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64 y = filter (a, 1, x); |
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65 else |
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66 if(ly > la) |
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67 x = [a, (zeros (1, ly - la))]; |
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68 else |
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69 x = a; |
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70 endif |
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71 y = filter (b, 1, x); |
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72 endif |
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73 |
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74 endfunction |
