Interpolation algorithm for computing Drazin inverse of polynomial matrices

In this paper we introduce an interpolation method for computing the Drazin inverse of a given polynomial matrix. This method is an extension of the known method from [A. Schuster, P. Hippe, Inversion of polynomial matrices by interpolation, IEEE Trans. Automat. Control 37 (3) (1992) 363–365], applicable to usual matrix inverse. Also, we improve our interpolation method, using a more effective estimation of degrees of polynomial matrices generated in Leverrier–Faddeev method. Algorithms are implemented and tested in the symbolic package MATHEMATICA.