Discretisation of continuous-time control systems with guaranteed stability [comment with reply]

The commenters refer to the paper by Markazi et al. (IEE Proc. Control Theory Appl. Vol.142, No.4 (1995)) and point out that when they simulated the step response for the three digital controllers and found, using both MATLAB and Program CC, that the results were similar to those given in the paper. However, on further investigation they found that the closed loop system was not asymptotically stable due to the presence of poles on and outside the unit circle. Thus it is concluded that the results given by the authors are clearly unstable and the validity of the paper must be questioned. In reply, Markazi et al. acknowledge that the issues of numerical stability and responses to a disturbance need to be clarified