In this note the representations of the Drazin inverse of a 2×2 block matrix M = [ A B C D ] , where A and D are square matrices, have been recently developed under some assumptions. We derive formulae for the Drazin inverse of a block matrix M under conditions weaker than those in the papers [9], [11], [12] and [14]. 2000 Mathematics Subject Classification: 15A09

In this paper a representation is given for the Drazin inverse of a 2 × 2 operator matrix, extending to Banach spaces results of Hartwig, Li and Wei [SIAM J. Matrix Anal. Appl., 27 (2006) pp. 757–771]. Also, formulae are derived for the Drazin inverse of an operator matrix M under some new conditions.

Block representations of the Drazin inverse of a bipartite matrix A = 2 4 0 B C 0 3 5 in terms of the Drazin inverse of the smaller order block product BC or CB are presented. Relationships between the index of A and the index of BC are determined, and examples are given to illustrate all such possible relationships.

By a generalized inverse of a given matrix, we mean a matrix that exists for a larger class of matrices than the nonsingular matrices, that has some of the properties of the usual inverse, and that agrees with inverse when given matrix happens to be nonsingular. In theory, there are many different generalized inverses that exist. We shall consider the Moore Penrose, weighted Moore-Penrose, Draz...

In this paper, we investigate the perturbation of the generalized Drazin invertible matrices and derive explicit generalized Drazin inverse expressions for the perturbations under certain restrictions on the perturbing matrices.

In several applications, e.g., in control and systems modeling theory, Drazin inverses and matrix pencil methods for the study of generalized (descriptor) linear systems are used extensively. In this paper, a relation between the Drazin inverse and the Kronecker canonical form of rectangular pencils is derived and fully investigated. Moreover, the relation between the Drazin inverse and the Wei...

In this paper we investigate the continuity of the Drazin inverse of a bounded linear operator on Banach space. Then as a corollary, among other things, we get the well known result of Campbell and Meyer ([1]) for the continuity of the Drazin inverse of square matrix.

We propose a finite algorithm for computing Drazin inverse of two-variable polynomial matrices based on Greville s finite algorithm for computing Drazin inverse of a constant matrix. Also a three-dimensional recursive algorithm to do that is deduced. Examples show that these methods are feasible and the implementation is developed in the symbolic package MATLAB. 2002 Elsevier Inc. All rights re...

We present some new representations for the generalized Drazin inverse of a block matrix with generalized Schur complement being generalized Drazin invertible in a Banach algebra under conditions weaker than those used in recent papers on the subject.

In this paper we investigate additive properties of the generalized Drazin inverse in a Banach algebra. We find some new conditions under which the generalized Drazin inverse of the sum a + b could be explicitly expressed in terms of a, a, b, b. Also, some recent results of Castro and Koliha (Proc. Roy. Soc. Edinburgh Sect. A 134 (2004), 1085-1097) are extended. 2000 Mathematics Subject Classif...