Riccati equation
X=ric_desc(H [,E))
[X1,X2,zero]=ric_desc(H [,E])
:H,E real square matrices : :X1,X2 real square matrices : :zero real number :
Riccati solver with hamiltonian matrices as inputs.
In the continuous time case calling sequence is ric_descr(H) (one input):
Riccati equation is:
(Ec) A'*X + X*A + X*R*X -Q = 0.
Defining the hamiltonian matrix H by:
H = [A R;
Q -A']
with the calling sequence [X1,X2,zero]=ric_descr(H), the solution X is given by X=X1/X2.
zero = L1 norm of rhs of ( Ec)
The solution X is also given by X=riccati(A,Q,R,’c’))
In the discrete-time case calling sequence is ric_descr(H,E) (two inputs):
The Riccati equation is:
(Ed) A'*X*A-(A'*X*B*(R+B'*X*B)^-1)*(B'*X*A)+C-X = 0.
Defining G=B/R*B’ and the hamiltonian pencil (E,H) by:
E=[`eye`_(n,n),G; H=[A, 0*`ones`_(n,n);
0*`ones`_(n,n),A'] -C, `eye`_(n,n)];
with the calling sequence [X1,X2,err]=ric_descr(H,E), the solution X is given by X=X1/X2.
zero`= L1 norm of rhs of ( `Ed)
The solution X is also given by X=riccati(A,G,C,’d’) with G=B/R*B’