111 6.3 Polcs and % c w s of the System Function S H ( s )= -k Tm( s } 10 x ~ pole -zero double E'igurc 6.10: Examples of' pole-zero diagram!: ratioiial fractioii s y h t ~ n ifiinctiorr call A t ) take r ~ i ~ i p \ialirclh l e ~ For polynoixiialr with real coefficients Iiowevm they alwnvs occur iii complex conjugate pairs Figiire (i.11 shows a sirnplcl rxarrtpl[J I1n{s) X Double zero at s = \ I role> s = - 1ic j X li-2 I I ( )= (,? +,])(A + - , I ) K ~ - s2 I- 2s Figure 11: Pole-zero diagram with conjugated complcx polpq +2