  We use first-order perturbation theory to provide a local linear relation
between the circuit parameters and the poles of an RLC network. The sensitivity
matrix, which defines this relationship, is obtained from the systems
eigenvectors and the derivative of its eigenvalues. In general, the sensitivity
matrix is related to the equilibrium fluctuations of the system. In particular,
it may be used as the basis for a statistical model to efficiently predict the
sensitivity of the circuit response to small component variations. The method
is illustrated with a calculation of conditional probabilities by Monte Carlo
Simulation.
