Quadratic stability of interval matrices

Deals with the quadratic stability of interval matrices. The results in this paper can be divided into two parts. In the first, the authors use the fact that quadratic stability of the family {A₀ +DFE, ||F||₂⩽r} is equivalent to a small gain condition. The authors use this fact to obtain a sufficient condition for the quadratic stability of an interval matrix family. The authors then investigate whether this overbound can be sharpened via a judicious choice of nominal A₀. In the second part, the authors consider interval matrices expressed in companion form and explore possible linkage between quadratic stability and Kharitonov´s result for interval polynomials