A review of the matrix Riccati equation

As usual, R denotes the field of real numbers, R" stands for the n-dimensional vector space over R, a prime denotes the transpose of a matrix, an asterisk denotes the complex conjugate transpose of a matrix, and P _ Q means that P — Q is hermitian or real symmetric nonnegative matrix. Square brackets represent matrices composed of the symbols inside. In order to get a better motivation for the problems to be discussed we first pose the underlying physical problem. Given the linear, continuous-time, constant system