You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: poly2ac.m
    path of file: ./repos/malini/Codes/FC_EC_calculation code/DynamicEC/tsa
    
    the code of the file until where you have to start completion: function ACF=poly2ac(a,efinal)
% converts an AR polynomial into an autocorrelation sequence
% [R] = poly2ac(a [,efinal] );
%
% see also ACOVF ACORF AR2RC RC2AR DURLEV AC2POLY, POLY2RC, RC2POLY, RC2AC, AC2RC, POLY2AC
% 

%       $Id: poly2ac.m 5090 2008-06-05 08:12:04Z schloegl $
%       Copyright (C) 1998-2002,2008 by Alois Schloegl <a.schloegl@ieee.org>
%
%    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/>.


fprintf(2,'ERROR: POLY2AC does not work yet. Sorry\n');
return;


    
function ACF=poly2ac(a,efinal)
% converts an AR polynomial into an autocorrelation sequence
% [R] = poly2ac(a [,efinal] );
%
% see also ACOVF ACORF AR2RC RC2AR DURLEV AC2POLY, POLY2RC, RC2POLY, RC2AC, AC2RC, POLY2AC
% 

%       $Id: poly2ac.m 5090 2008-06-05 08:12:04Z schloegl $
%       Copyright (C) 1998-2002,2008 by Alois Schloegl <a.schloegl@ieee.org>
%
%    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/>.


fprintf(2,'ERROR: POLY2AC does not work yet. Sorry\n');
return;

mfilename='POLY2AC';
if ~exist('rc2ar','file')
        fprintf(2,'Error %s: RC2AR.M not found. \n Download TSA toolbox from http://www.dpmi.tu-graz.ac.at/~schloegl/matlab/tsa/\n',mfilename);
        return;
end