YALTA is a Matlab toolbox dedicated to the H  ∞ -stability analysis of classical and fractional systems with commensurate delays given by their transfer function, whose binary can be downloaded at http://team.inria.fr/disco/software/. 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 describe how we have circumvented the numerical issues of algorithms developed in [6, 8] and several examples are given Ver menos