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scripts/signal/fftconv.m

changeset 10289: 4b124317dc38
parent:93c65f2a5668
author: John W. Eaton <jwe@octave.org>
date: Tue Feb 09 20:58:55 2010 -0500 (48 minutes ago)
permissions: -rw-r--r--
description: base_properties::set_children: account for hidden children 
     1## Copyright (C) 1994, 1995, 1996, 1997, 1999, 2000, 2002, 2005, 2006,

     2##               2007 John W. Eaton

     3##

     4## This file is part of Octave.

     5##

     6## Octave is free software; you can redistribute it and/or modify it

     7## under the terms of the GNU General Public License as published by

     8## the Free Software Foundation; either version 3 of the License, or (at

     9## your option) any later version.

    10##

    11## Octave is distributed in the hope that it will be useful, but

    12## WITHOUT ANY WARRANTY; without even the implied warranty of

    13## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

    14## General Public License for more details.

    15##

    16## You should have received a copy of the GNU General Public License

    17## along with Octave; see the file COPYING.  If not, see

    18## <http://www.gnu.org/licenses/>.

    19

    20## -*- texinfo -*-

    21## @deftypefn {Function File} {} fftconv (@var{a}, @var{b}, @var{n})

    22## Return the convolution of the vectors @var{a} and @var{b}, as a vector

    23## with length equal to the @code{length (a) + length (b) - 1}.  If @var{a}

    24## and @var{b} are the coefficient vectors of two polynomials, the returned

    25## value is the coefficient vector of the product polynomial.

    26##

    27## The computation uses the FFT by calling the function @code{fftfilt}.  If

    28## the optional argument @var{n} is specified, an N-point FFT is used.

    29## @end deftypefn

    30

    31## Author: KH <Kurt.Hornik@wu-wien.ac.at>

    32## Created: 3 September 1994

    33## Adapted-By: jwe

    34

    35function c = fftconv (a, b, N)

    36

    37  if (nargin < 2 || nargin > 3)

    38    print_usage ();

    39  endif

    40

    41  if (! (isvector (a) && isvector (b)))

    42    error ("fftconv: both a and b should be vectors");

    43  endif

    44  la = length (a);

    45  lb = length (b);

    46  if ((la == 1) || (lb == 1))

    47    c = a * b;

    48  else

    49    lc = la + lb - 1;

    50    a(lc) = 0;

    51    b(lc) = 0;

    52    if (nargin == 2)

    53      c = fftfilt (a, b);

    54    else

    55      if (! (isscalar (N)))

    56        error ("fftconv: N has to be a scalar");

    57      endif

    58      c = fftfilt (a, b, N);

    59    endif

    60  endif

    61

    62endfunction