Integration-free interval doubling for Riccati equation solutions

Starting with certain identifies obtained by Reid [6] and Redheffer [11] for general matrix Riccati equations (RE´s), we give various algorithms for the case of constant coefficients. The algorithms are based on two ideas-first, relate the RE solution with general initial conditions to anchored RE solutions; and second, when the coefficients are constant, the anchored solutions have a basic shift-invariance property. These ideas are used to construct an integration-free, superlinearly convergent iterative solution to the algebraic RE. Preliminary numerical experiments show that our algorithms, arranged in square-root form, provide a method that is numerically stable and appears to be competitive with other methods of solving the algebraic RE.