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function [A,C,rcnd]=findAC(s,n,l,R,meth,tol,printw)
A=[];C=[];rcnd=[];
[nargout,nargin] = argn(0)
//FINDAC Finds the system matrices A and C of a discrete-time system, given the
// system order and the relevant part of the R factor of the concatenated
// block-Hankel matrices, using subspace identification techniques (MOESP
// or N4SID).
//
// [A,C] = FINDAC(S,N,L,R,METH,TOL,PRINTW) computes the system matrices
// A and C. The model structure is:
//
// x(k+1) = Ax(k) + Bu(k) + Ke(k), k >= 1,
// y(k) = Cx(k) + Du(k) + e(k),
//
// where x(k) and y(k) are vectors of length N and L, respectively.
//
// [A,C,RCND] = FINDAC(S,N,L,R,METH,TOL,PRINTW) also returns the vector
// RCND of length 4 containing the condition numbers of the matrices
// involved in rank decisions.
//
// S is the number of block rows in the block-Hankel matrices.
//
// METH is an option for the method to use:
// METH = 1 : MOESP method with past inputs and outputs;
// = 2 : N4SID method.
// Default: METH = 1.
// Matrix R, computed by FINDR, should be determined with suitable arguments
// METH and JOBD.
//
// TOL is the tolerance used for estimating the rank of matrices.
// If TOL > 0, then the given value of TOL is used as a lower bound
// for the reciprocal condition number.
// Default: prod(size(matrix))*epsilon_machine where epsilon_machine
// is the relative machine precision.
//
// PRINTW is a select for printing the warning messages.
// PRINTW = 1: print warning messages;
// = 0: do not print warning messages.
// Default: PRINTW = 0.
//
// See also FINDABCD, FINDBD, FINDBDK, FINDR, ORDER, SIDENT
//
// V. Sima 18-01-2000.
//
// Revisions:
//
nin = nargin;
nout = nargout;
//
if nin<7 then
printw = 0;
end
if nin<6 then tol = 0;end
if tol==[] then tol = 0;end
if nin<5 then meth = 1;end
if meth==[] then meth = 1;end
if nin<4 then
error('Wrong number of input arguments');
end
//
// Compute system matrices A and C.
job = 2;
nsmpl = 0;
if nout==1 then
A = sident(meth,job,s,n,l,R,tol,nsmpl,[],[],printw);
elseif nout==2 then
[A,C] = sident(meth,job,s,n,l,R,tol,nsmpl,[],[],printw);
elseif nout==3 then
[A,C,rcnd] = sident(meth,job,s,n,l,R,tol,nsmpl,[],[],printw);
else
error('Wrong number of output arguments');
end
//
// end findAC
endfunction
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