In an electrical network, ω is a natural angular frequency of a response function f (t) if the Laplace transform F (s) of f (t) includes the term Ke, where s = σ + ω i for a real σ, and K ≠ 0 is a constant. Natural frequencies depend on network topology and element values but not their input. It can be shown that the set of natural frequencies in a network can be obtained by calculating the poles of all impedance and admittance functions of the network. A pole of the network transfer function is associated with a natural angular frequencies of the corresponding response variable; however there may exist some natural angular frequency that does not correspond to a pole of the network function. These happen at some special initial states.