YALTA: a Matlab toolbox for the H∞-stability analysis of classical and fractional systems with commensurate delays

In this paper we describe YALTA, a Matlab toolbox dedicated to the H∞-stability analysis of classical and fractional systems with commensurate delays given by their transfer function. Delay systems of both retarded and neutral type are considered. The asymptotic position of high modulus poles is given. For a fixed known delay, poles of small modulus of standard delay systems are approximated through a Padé-2 scheme. For a delay varying from zero to a prescribed positive value, stability windows as well as root loci are given. We deeply describe how we have circumvented the numerical issues of algorithms developed in Fioravanti et al. [2010a, 2012] as well as the limitations of this toolbox. Finally, several examples are given.