General Solution of a Three-dimensional Linear Difference System with a Delay

The paper analyzes a partial case of a delayed linear three-dimensional discrete system z(k+ 1) = Az(k) + Bz(k-1) + U(k), k = 0, 1,..., where A and B are constant 3 by 3 matrices, U: {0, 1,...} -> R-3 and z: {-1, 0,...} -> R-3. Matrices A, B and function U are specified in such a way that the system is a discrete analogue of a differential model of the Mach number dynamics concerning a time-optimal control of a high-speed closed-circuit wind tunnel. The general solution is found by transforming this system into a solvable non-delayed one.