In our book , we proposed some stability test theorems for linear time-delay system.
To verify our stability test theorems and others' stability test algorithms , we provide this simulation program of time-delay systems.
You can use the program, to find that the results of  are incorrecct.
The following example is taken from the case 1 of , where  claimed to found a stable region for the time-delay system of case 1,however, the simulation shows that the time-delay system of case 1 is unstable,
with delay parameters: t1=.4;t2=.5; t3=.169;t4=0.26.
Thus, the main results of  are incorrect.
 Yang Xiao, Yingkang Zhang, Multidimensional Signal Processing and
Multidimensional Systems, Publishing House of Electronics Industry,
 Rifat Sipahi and Ismail Ilker Delice, Advanced Clustering With Frequency Sweeping Methodology for the Stability Analysis of Multiple Time-Delay Systems,IEEE TRANSACTIONS ON AUTOMATIC CONTROL, VOL. 56, NO. 2, 2011, pp.467-472.