riccati - Riccati equation
X=riccati(A,B,C,dom,[typ]) solves the Riccati equation:
A'*X+X*A-X*B*X+C=0
in continuous time case, or:
A'*X*A-(A'*X*B1/(B2+B1'*X*B1))*(B1'*X*A)+C-X
with B=B1/B2*B1' in the discrete time case. If called with two output arguments, riccati returns X1,X2 such that X=X1/X2.