Local realizations of time varying descriptor systems

A method of realizing a descriptor system E(t)x´(t)+F(t)x(t) = B(t)u(t) as a state space system y´ = A(t)y(t) + ??i=0 lKi(t)u(i)(t) x = M(t)y(t) + ??i=0 lNi(t)u(i)(t) is developed. This realization has the important property that the coefficients A, Ki, M, N, are computed directly from arrays of derivatives of E, F, B, u. Thus no time varying coordinate changes need to be performed prior to any differentiations making the method easy to implement numerically.