Region of convergence (ROC) For any given sequence,the set of values of z for which the z-transform converges is called the Region Of Convergence(ROC). X(z)=∑x[nz"→x(z≤∑[n]lz”. n=-00 z=re n=-00 Absolute Summability X(eo)=∑（[n-"）eom 1n二-00 X(re∑[n]r<∞ n=-00 Convergence of the z-transform for a given sequence depends only on r=z 88 Region of convergence (ROC) ◆For any given sequence, the set of values of z for which the z-transform converges is called the Region Of Convergence (ROC). ( )   n n X z x n z  − =− =  [ ] j n n X re x n r   − =− （ ）    ( ) [ ] n n X z x n z  − =     - j z re  = Absolute Summability ( [ ] ) j n j n n X re x n r e    − − =− （ ）=  r z = ◆Convergence of the z-transform for a given sequence depends only on