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1 ## Copyright (C) 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2002, 2004, |
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2 ## 2005, 2006, 2007 John W. Eaton |
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3 ## |
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4 ## This file is part of Octave. |
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5 ## |
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6 ## Octave is free software; you can redistribute it and/or modify it |
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7 ## under the terms of the GNU General Public License as published by |
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8 ## the Free Software Foundation; either version 3 of the License, or (at |
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9 ## your option) any later version. |
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10 ## |
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11 ## Octave is distributed in the hope that it will be useful, but |
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12 ## WITHOUT ANY WARRANTY; without even the implied warranty of |
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13 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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14 ## General Public License for more details. |
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15 ## |
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16 ## You should have received a copy of the GNU General Public License |
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17 ## along with Octave; see the file COPYING. If not, see |
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18 ## <http://www.gnu.org/licenses/>. |
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19 |
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20 ## -*- texinfo -*- |
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21 ## @deftypefn {Function File} {} conv (@var{a}, @var{b}) |
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22 ## Convolve two vectors. |
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23 ## |
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24 ## @code{y = conv (a, b)} returns a vector of length equal to |
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25 ## @code{length (a) + length (b) - 1}. |
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26 ## If @var{a} and @var{b} are polynomial coefficient vectors, @code{conv} |
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27 ## returns the coefficients of the product polynomial. |
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28 ## @seealso{deconv, poly, roots, residue, polyval, polyderiv, polyinteg} |
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29 ## @end deftypefn |
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30 |
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31 ## Author: Tony Richardson <arichard@stark.cc.oh.us> |
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32 ## Created: June 1994 |
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33 ## Adapted-By: jwe |
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34 |
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35 function y = conv (a, b) |
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36 |
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37 if (nargin != 2) |
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38 print_usage (); |
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39 endif |
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40 |
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41 if (! (isvector (a) && isvector (b))) |
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42 error("conv: both arguments must be vectors"); |
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43 endif |
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44 |
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45 la = length (a); |
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46 lb = length (b); |
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47 |
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48 ly = la + lb - 1; |
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49 |
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50 ## Ensure that both vectors are row vectors. |
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51 if (rows (a) > 1) |
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52 a = reshape (a, 1, la); |
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53 endif |
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54 if (rows (b) > 1) |
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55 b = reshape (b, 1, lb); |
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56 endif |
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57 |
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58 ## Use the shortest vector as the coefficent vector to filter. |
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59 if (la < lb) |
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60 if (ly > lb) |
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61 x = [b, (zeros (1, ly - lb))]; |
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62 else |
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63 x = b; |
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64 endif |
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65 y = filter (a, 1, x); |
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66 else |
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67 if(ly > la) |
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68 x = [a, (zeros (1, ly - la))]; |
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69 else |
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70 x = a; |
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71 endif |
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72 y = filter (b, 1, x); |
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73 endif |
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74 |
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75 endfunction |
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76 |
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77 %!assert(all (all (conv (ones (3, 1), ones (3, 1)) == [1, 2, 3, 2, 1]))); |
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78 |
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79 %!assert(all (all (conv (ones (1, 3), ones (3, 1)) == [1, 2, 3, 2, 1]))); |
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80 |
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81 %!assert(all (all (conv (3, [1, 2, 3]) == [3, 6, 9]))); |
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82 |
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83 %!error conv ([1, 2; 3, 4], 3); |
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84 |
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85 %!assert(conv (2, 3),6); |
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86 |
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87 %!error conv (2, []); |
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88 |
