The resulting controller is of the order of 2dn, which
is the lowest obtainable order required for the disturbance
cancellation. The controller design includes two
diagonal parameter matrices defining the applied control
effort and the penalty for the filtered process
output. In essence, the filtering approach yields such
optimal control signal that after passing through the
process dynamics, the output signal is the complement
of the disturbance, hence cancelling the disturbance.