A Simple Necessary And Sufficient Condition Of Asymptotic Stability For Scalar Fornasini-Marchesini Models

A simple and straightforward sufficient and necessary condition is given to check the asymptotic stability of 2D scalar Fornasini-Marchesini models. The condition only looks at the absolute value of the constants of the model and hence make it very practical to derive simple examples. A possible extension to the matrix case is discussed notably when the matrices commute.