function outsig=filterbankz(b,a,insig,hopsize)
%FILTERBANKZ Filter bank with zero boundary condition
% Usage: outsig=filterbankz(b,a,insig);
% outsig=filterbankz(b,a,insig,hopsize);
%
% FILTERBANKZ(b,a,insig,hopsize) filters the input signal with the
% filters described in a and b. hopsize is a vector with a length
% equal to the number of filters. Each channel is sub-sampled by the
% corresponding hopsize.
%
% If a and b are matrices then each row corresponds to a subband
% channel.
%
% If insig is a matrix then filtering is applied along the columns.
%
% The output coefficients are stored a cell array. More precisely, the
% n'th cell of c, c{m}, is a 2D matrix of size M(n) xW and
% containing the output from the m'th channel subsampled at a rate of
% a(m). c{m}(n,l) is thus the value of the coefficient for time index
% n, frequency index m and signal channel l.
%
% See also: gammatone, ufilterbankz, auditoryfilterbank
%
% Url: http://amtoolbox.sourceforge.net/data/amt-test/htdocs/amt-0.9.8/doc/general/filterbankz.php
% Copyright (C) 2009-2015 Piotr Majdak and Peter L. Søndergaard.
% This file is part of AMToolbox version 0.9.8
%
% 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/>.
% AUTHOR : Peter L. Søndergaard
%% ------ Checking of input parameters ---------
error(nargchk(4,4,nargin));
%% ------ Computation --------------------------
[insig,siglen,dummy,nsigs,dim,permutedsize,order]=assert_sigreshape_pre(insig,[],[], ...
upper(mfilename));
nchannels=size(b,1);
outsig=cell(nchannels,1);
for ii=1:nchannels
% Calculate the new length in the time domain of this channel
outlen=ceil(siglen/hopsize);
% Do the actual filtering.
res = filter(b(ii,:),a(ii,:),insig);
% Subsample the output, reshape a multidimensional array to the correct size and store.
permutedsize(1)=outlen;
outsig{ii} = assert_sigreshape_post(res(1:hopsize:siglen,:),dim,permutedsize,order);
end;