Stability
A system is stable if any bounded input produces a bounded output for all bounded initial conditions.
Basic concept of stability
Stability of the system and roots of characteristic equations
Characteristic Equation
Consider an nth-order system whose the characteristic equation (which is also the denominator of the transfer function) is
a(S) = Sn+a1 Sn-1+ a2 Sn-2+……+ an-1 S1+ a0 S0
