function [Gd,K,R]=decouple(G)
% 計算多變量控制系統的解耦網絡Gd及狀態反饋矩陣

% Copyright 2001-2002 ECUST. 
%   $Revision: 1.1 $  $Date: 2002/01/26 14:18:26 $

G=ss(G);a=G.a;b=G.b;c=G.c;d=G.d;[m,n]=size(c);D0=c(1,:)*b;alf(1)=0;
for i=2:m;for j=0:n-1;D0=[D0;c(i,:)*a^j*b];
    if rank(D0)==i,alf(i)=j;break;else D0=D0(1:i-1,:);end;
end;end;
R=inv(D0);L=c(1,:)*a^(alf(1)+1);for i=2:m;L=[L;c(i,:)*a^(alf(i)+1)];end;
K=R*L;bd=b*R;cd=c-d*K;dd=d*R;ad=a-b*K;Gd=ss(ad,bd,cd,dd);