“…Introduction. The Drazin inverse of an operator or a matrix has various applications in singular differential equations and singular difference equations, Markov chains, and iterative methods (see [1,2,3,4,16,17,22,23,30]). In addition, the perturbation analysis of the Drazin inverse is important from the perspectives of both pure and computational mathematics (see [2]- [4], [6]- [7], [19]- [29]).…”