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scripts/polynomial/conv.m

changeset 10289: 4b124317dc38
parent:38a0f9dc0ab4
author: John W. Eaton <jwe@octave.org>
date: Tue Feb 09 20:58:55 2010 -0500 (44 minutes ago)
permissions: -rw-r--r--
description: base_properties::set_children: account for hidden children 
     1## Copyright (C) 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2002, 2004,

     2##               2005, 2006, 2007, 2008, 2009 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} {} conv (@var{a}, @var{b})

    22## Convolve two vectors.

    23##

    24## @code{y = conv (a, b)} returns a vector of length equal to

    25## @code{length (a) + length (b) - 1}.

    26## If @var{a} and @var{b} are polynomial coefficient vectors, @code{conv}

    27## returns the coefficients of the product polynomial.

    28## @seealso{deconv, poly, roots, residue, polyval, polyderiv, polyint}

    29## @end deftypefn

    30

    31## Author: Tony Richardson <arichard@stark.cc.oh.us>

    32## Created: June 1994

    33## Adapted-By: jwe

    34

    35function y = conv (a, b)

    36

    37  if (nargin != 2)

    38    print_usage ();

    39  endif

    40

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

    42    error ("conv: both arguments must be vectors");

    43  endif

    44

    45  la = length (a);

    46  lb = length (b);

    47

    48  ly = la + lb - 1;

    49

    50  ## Use the shortest vector as the coefficent vector to filter.

    51  ## Preserve the row/column orientation of the longer input.

    52  if (la <= lb)

    53    if (ly > lb)

    54      if (size (b, 1) <= size (b, 2))

    55        x = [b, (zeros (1, ly - lb))];

    56      else

    57        x = [b; (zeros (ly - lb, 1))];

    58      endif

    59    else

    60      x = b;

    61    endif

    62    y = filter (a, 1, x);

    63  else

    64    if (ly > la)

    65      if (size (a, 1) <= size (a, 2))

    66        x = [a, (zeros (1, ly - la))];

    67      else

    68        x = [a; (zeros (ly - la, 1))];

    69      endif

    70    else

    71      x = a;

    72    endif

    73    y = filter (b, 1, x);

    74  endif

    75

    76endfunction

    77

    78%!test

    79%!  x = ones(3,1);

    80%!  y = ones(1,3);

    81%!  b = 2;

    82%!  c = 3;

    83%!  assert (conv (x, x), [1; 2; 3; 2; 1]);

    84%!  assert (conv (y, y), [1, 2, 3, 2, 1]);

    85%!  assert (conv (x, y), [1, 2, 3, 2, 1]);

    86%!  assert (conv (y, x), [1; 2; 3; 2; 1]);

    87%!  assert (conv (c, x), [3; 3; 3]);

    88%!  assert (conv (c, y), [3, 3, 3]);

    89%!  assert (conv (x, c), [3; 3; 3]);

    90%!  assert (conv (y, c), [3, 3, 3]);

    91%!  assert (conv (b, c), 6);

    92%!error conv ([1, 2; 3, 4], 3);

    93%!error conv (2, []);

    94

    95%!test

    96%!  a = 1:10;

    97%!  b = 1:3;

    98%!  assert (size(conv(a,b)), [1, numel(a)+numel(b)-1])

    99%!  assert (size(conv(b,a)), [1, numel(a)+numel(b)-1])

   100

   101%!test

   102%!  a = (1:10).';

   103%!  b = 1:3;

   104%!  assert (size(conv(a,b)), [numel(a)+numel(b)-1, 1])

   105%!  assert (size(conv(b,a)), [numel(a)+numel(b)-1, 1])

   106

   107%!test

   108%!  a = 1:10;

   109%!  b = (1:3).';

   110%!  assert (size(conv(a,b)), [1, numel(a)+numel(b)-1])

   111%!  assert (size(conv(b,a)), [1, numel(a)+numel(b)-1])