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Update docstrings for convolution family of functions (conv, conv2, fftconv)
author Rik <octave@nomad.inbox5.com>
date Thu, 07 Oct 2010 11:27:03 -0700
parents a1dbe9d80eee
children e79f59d31a74
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1 ## Copyright (C) 1994, 1995, 1996, 1997, 1999, 2000, 2002, 2005, 2006,
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2 ## 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} {} fftconv (@var{a}, @var{b})
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22 ## @deftypefnx {Function File} {} fftconv (@var{a}, @var{b}, @var{n})
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23 ## Convolve two vectors using the FFT for computation.
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24 ##
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25 ## @code{c = fftconv (@var{a}, @var{b})} returns a vector of length equal to
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26 ## @code{length (@var{a}) + length (@var{b}) - 1}.
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27 ## If @var{a} and @var{b} are the coefficient vectors of two polynomials, the
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28 ## returned value is the coefficient vector of the product polynomial.
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29 ##
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30 ## The computation uses the FFT by calling the function @code{fftfilt}. If
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31 ## the optional argument @var{n} is specified, an N-point FFT is used.
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32 ## @seealso{deconv, conv, conv2}
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33 ## @end deftypefn
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34
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35 ## Author: KH <Kurt.Hornik@wu-wien.ac.at>
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36 ## Created: 3 September 1994
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37 ## Adapted-By: jwe
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38
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39 function c = fftconv (a, b, N)
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40
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41 if (nargin < 2 || nargin > 3)
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42 print_usage ();
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43 endif
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44
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45 if (! (isvector (a) && isvector (b)))
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46 error ("fftconv: both A and B must be vectors");
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47 endif
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48 la = length (a);
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49 lb = length (b);
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50 if ((la == 1) || (lb == 1))
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51 c = a * b;
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52 else
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53 lc = la + lb - 1;
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54 a(lc) = 0;
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55 b(lc) = 0;
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56 if (nargin == 2)
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57 c = fftfilt (a, b);
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58 else
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59 if (! (isscalar (N)))
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60 error ("fftconv: N must be a scalar");
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61 endif
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62 c = fftfilt (a, b, N);
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63 endif
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64 endif
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65
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66 endfunction
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68 %% FIXME: Borrow tests from conv.m. May need a tolerance on the assert comparison