Factorization of the Popov function of a multivariable linear distributed parameter system in the non-coercive case: a penalization approach
We study the construction of an outer factor to a positive definite Popov function of a distributed parameter system. We assume that is a non-negative definite matrix with non-zero determinant. Coercivity is not assumed. We present a penalization approach which gives an outer factor just in the case when there exists any outer factor.