6.2.2. General Two-Dimensional, P—Dimensional Case 
More generally, as the expansion of Eq. 6.8, we can think of a system, diagrammed 
in Fig. 6.3, in which the output Xj, is fed back to the input X2, as well as the input X2, 
being fed to the output X) 
foe} le 2} 
Sena YS Chaim Konn & Epp 
Xt = 
l=1 u=1 
(6.17) 
lee} co 
269 = (Oriya SS, Cham Lone P CAN 
l=1 u=1 
Fig. 6.3. Two—dimensional feedback system. 
This equation can be written in vector form as 
Xie} _ | Cia Cra] | Xuer | | | C12 Crrz X12 
X21 Car Caza | | 420-1 C212 Cr2 | | 2.2 
Cc C Xi tk E 
+ Re agree eae rea | aa (6.18) 
Care Cr2¢ | | 220% €21 
Cutting off the terms at appropriate k by some criterion gives 
206 
