The methods of building convex multitudes of coefficients stability polynom

In theory robust stability important place is employs working of criterias of existing and researches of methods to building convex multitudes coefficients stability polynomials [1,2]. Isn't important problem appears the solution this task and for instability polynomials. In giving work is supposes criterias of existing convex multitudes instability polynomials is belongs to one definite class of instability. This criteries is allows of way checking limit number of conditions, imposing on polynomials, organizes this family, is installs measures of all this family polynomial.