Linearization about constant operating points: An input-output viewpoint

For a class of stationary nonlinear systems that can be described by Volterra series, input-output definitions of the familiar notions of a constant operating point and the corresponding linearized system are discussed. Some recent results are reviewed with emphasis on the motivation for the input-output formulation. Then, to illustrate the utility of the approach, the problem of finding the linearization of an interconnection of nonlinear systems in terms of the subsystem linearizations is considered.