/usr/share/octave/packages/signal-1.3.2/convmtx.m is in octave-signal 1.3.2-1+b1.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 | ## Copyright (C) 2003 David Bateman <adb014@gmail.com>
##
## This program is free software; you can redistribute it and/or modify it under
## the terms of the GNU General Public License as published by the Free Software
## Foundation; either version 3 of the License, or (at your option) any later
## version.
##
## This program is distributed in the hope that it will be useful, but WITHOUT
## ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
## FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
## details.
##
## You should have received a copy of the GNU General Public License along with
## this program; if not, see <http://www.gnu.org/licenses/>.
## -*- texinfo -*-
## @deftypefn {Function File} {} convmtx (@var{a}, @var{n})
## If @var{a} is a column vector and @var{x} is a column vector
## of length @var{n}, then
##
## @code{convmtx(@var{a}, @var{n}) * @var{x}}
##
## gives the convolution of of @var{a} and @var{x} and is the
## same as @code{conv(@var{a}, @var{x})}. The difference is if
## many vectors are to be convolved with the same vector, then
## this technique is possibly faster.
##
## Similarly, if @var{a} is a row vector and @var{x} is a row
## vector of length @var{n}, then
##
## @code{@var{x} * convmtx(@var{a}, @var{n})}
##
## is the same as @code{conv(@var{x}, @var{a})}.
## @end deftypefn
## @seealso{conv}
function b = convmtx (a, n)
if (nargin != 2)
print_usage;
endif
[r, c] = size(a);
if ((r != 1) && (c != 1)) || (r*c == 0)
error("convmtx: expecting vector argument");
endif
b = toeplitz([a(:); zeros(n-1,1)],[a(1); zeros(n-1,1)]);
if (c > r)
b = b.';
endif
endfunction
%!assert(convmtx([3,4,5],3),[3,4,5,0,0;0,3,4,5,0;0,0,3,4,5])
%!assert(convmtx([3;4;5],3),[3,0,0;4,3,0;5,4,3;0,5,4;0,0,5])
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