FILTERBANKLENGTH - Filterbank length from signal

function L=filterbanklength(Ls,a)
%FILTERBANKLENGTH  Filterbank length from signal
%   Usage: L=filterbanklength(Ls,a);
%
%   FILTERBANKLENGTH(Ls,a) returns the length of a filterbank with
%   time shifts a, such that it is long enough to expand a signal of
%   length Ls.
%
%   If the filterbank length is longer than the signal length, the signal
%   will be zero-padded by FILTERBANK or UFILTERBANK.
%
%   If instead a set of coefficients are given, call FILTERBANKLENGTHCOEF.
%
%   See also: filterbank, filterbanklengthcoef
%
%   Url: http://ltfat.github.io/doc/filterbank/filterbanklength.html

% Copyright (C) 2005-2023 Peter L. Soendergaard <peter@sonderport.dk> and others.
% This file is part of LTFAT version 2.6.0
%
% 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/>.

complainif_notenoughargs(nargin,2,upper(mfilename));
complainif_notposint(Ls,'Ls',upper(mfilename));

if ~isnumeric(a) || any(a(:)<=0)
  error('%s: "a" must be numeric consisting of positive numbers ony.',...
        upper(mfilename));
end;

if isvector(a)
    a= a(:);
end

lcm_a=a(1);
for m=2:size(a,1)
  lcm_a=lcm(lcm_a,a(m,1));
end;

L=ceil(Ls/lcm_a)*lcm_a;