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[project @ 1995-01-11 20:52:10 by jwe]
author jwe
date Wed, 11 Jan 1995 20:52:10 +0000
parents 3470f1e25a79
children 611d403c7f3d
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1 # Copyright (C) 1995 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 the
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7 # Free Software Foundation; either version 2, or (at your option) any
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8 # later version.
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9 #
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10 # Octave is distributed in the hope that it will be useful, but WITHOUT
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11 # ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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12 # FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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13 # 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, 675 Mass Ave, Cambridge, MA 02139, USA.
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18
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19 function y = conv (a, b)
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20
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21 # usage: conv (a, b)
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22 #
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23 # Convolve two vectors.
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24 #
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25 # y = conv (a, b) returns a vector of length equal to length (a) +
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26 # length (b) -1.
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27 #
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28 # If a and b are polynomial coefficient vectors, conv returns the
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29 # coefficients of the product polynomial.
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30 #
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31 # SEE ALSO: deconv, poly, roots, residue, polyval, polyderiv, polyinteg
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32
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33 # Written by Tony Richardson (amr@mpl.ucsd.edu) June 1994.
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34
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35 if (nargin != 2)
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36 usage ("conv(a, b)");
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37 endif
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38
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39 if (is_matrix (a) || is_matrix (b))
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40 error("conv: both arguments must be vectors");
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41 endif
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42
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43 la = length (a);
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44 lb = length (b);
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45
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46 ly = la + lb - 1;
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47
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48 # Ensure that both vectors are row vectors.
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49 if (rows (a) > 1)
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50 a = reshape (a, 1, la);
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51 endif
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52 if (rows (b) > 1)
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53 b = reshape (b, 1, lb);
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54 endif
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55
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56 # Use the shortest vector as the coefficent vector to filter.
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57 if (la < lb)
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58 if (ly > lb)
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59 x = [b, zeros (1, ly - lb)];
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60 else
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61 x = b;
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62 endif
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63 y = filter (a, 1, x);
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64 else
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65 if(ly > la)
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66 x = [a, zeros (1, ly - la)];
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67 else
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68 x = a;
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69 endif
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70 y = filter (b, 1, x);
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71 endif
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72
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73 endfunction