function [res] = ABCDshunt(f,R,C,L)
%ABCDshunt - Generate a ABCD matrix corresponding to a shunt impedance
%
% Parameter:    f          Frequencies to use
%               R          The shunt R
%               C          The shunt C
%               L          The shunt L
% Returns:      res        The resulting ABCD matrix
%
% Example(s):
%
% Reference:
% 
%% ===========================================================================

%% ===========================================================================
% Copyright (C):                                        
%       2001-2009 by Forschungszentrum Telekommunikation Wien, Austria;
%                                                         All rights reserved.
% Project       : FTW's xDSLsimu
% Author(s)     : Tomas Nordstrom (Tomas.Nordstrom@FTW.at)
%		: Petr Kadlec (kadlec@ftw.at)
%
% CVS:       $Id: ABCDshunt.m 752 2009-01-02 13:03:52Z tono $
%% ===========================================================================
% Change History
%      2001-11-10 (ToNo) Created
%      2002-07-22 (Peka) Octave port
%      2003-11-03 (ToNo) Lists now use cell arrays for both Octave and Matlab
%% ===========================================================================

nf = size(f);

if nargin<4,
    jwL=inf;
else
    jwL=j*2*pi*f*L;
end;

if (nargin<3) || (C==0),
    jwC=0;
else
    jwC=j*2*pi*f*C;
end;

if R==0;
    R=inf;
end;
R=R*ones(nf);

OoZ= 1./R + jwC + 1./jwL;

res={{ones(nf), zeros(nf)},...
     {OoZ, ones(nf)}};