“…Recently, a number of direct methods for stability analysis were proposed with their respective numerical formulations [39], [33]. While avoiding the truncation of the PDE dynamics, these methods impose a set of basis functions to obtain a numerical verification of the infinite dimensional inequalities, see for instance [17], where an orthogonal set of polynomials were used, and [40], where a standard polynomial basis is used. For timedelay systems, a particular class of infinite-dimensional systems, necessity and sufficiency of a class of LFs, called complete quadratic functionals, has been shown in [22,Chapter 5].…”