Numerical methods for problems involving the Drazin inverse

The objective was to try to develop a useful numerical algorithm for the Drazin inverse and to analyze the numerical aspects of the applications of the Drazin inverse relating to the study of homogeneous Markov chains and systems of linear differential equations with singular coefficient matrices. It is felt that all objectives were accomplished with a measurable degree of success

Characterizations of a class of matrices and perturbation of the Drazin inverse

Este trabajo supone un avance en la caracterización y representación de una clase de matrices perturbadas, para el estudio de la perturbación de la inversa de Drazin. Se obtienen diversas caracterizaciones de las matrices perturbadas: geométrica, algebraica, en función de los rangos, y respecto una representación matricial por bloques. Con estas caracterizaciones se alcanzan expresiones explícitas de la inversa de Drazin de la matriz perturbada, y cotas del error relativo de la perturbación de la inversa de Drazin. Se presentan ejemplos numéricos en los que se comparan las cotas dadas con otras publicadas recientemente en la literatura. Como aplicación, se presentan resultados relativos a la continuidad de la inversa de Drazin. Given a singular square matrix $A$ with index $r$, $\operatorname{ind}(A)=r$, we establish several characterizations in the Drazin inverse framework of the class of matrices $B$, which satisfy the conditions $\mathcal{N}(B^s)\cap\mathcal{R}(A^r)=\{0\}$ and $\mathcal{R}(B^s)\cap\mathcal{N}(A^r)=\{0\}$ with $\operatorname{ind}(B)=s$, where $\mathcal{N}(A)$ and $\mathcal{R}(A)$ denote the null space and the range space of a matrix $A$, respectively. We give explicit representations for $B^{\rm D}$ and $BB^{\rm D}$ and upper bounds for the errors $\|B^{\rm D}-A^{\rm D}\|/\|A^{\rm D}\|$ and $\|BB^{\rm D}-AA^{\rm D}\|$. In a numerical example we show that our bounds are better than others given in the literature

The perturbation of the Drazin inverse and oblique projection

AbstractLet A and E be n × n matrices and B = A+E. Denote the Drazin inverse of A by Ad. We present bounds for ∥Bd∥, ∥BdB∥, ∥Bd − Ad∥∥Ad∥, and ∥BdB − AdA∥∥AdA∥ under the weakest condition core rank B = core rankA. The hard problem due to Campbell and Meyer in [1] is completely solved

On the perturbation of the group generalized inverse for a class of bounded operators in Banach spaces

En este trabajo se estudia la perturbación de la inversa generalizada grupo en el ámbito de los operadores lineales y acotados sobre un espacio de Banach complejo. Se establecen, en primer lugar, caracterizaciones de los {1,2}-inversos generalizados de operadores perturbados que verifican una condición de no singularidad. Posteriormente se caracteriza la clase de operadores perturbados para los cuales existe el operador inverso grupo y verifican ciertas condiciones geométricas. Se prueba que los operadores perturbados tienen una determinada estructura de matriz 2 por 2 de operadores y se desarrolla una representación para la resolvente de tales matrices de operadores a partir de la cual se obtiene una representación para el operador inverso grupo. Este resultado extiende al contexto de operadores un resultado para matrices por bloques incluido en el libro [Campbell y Meyer, Generalized inverses of Linear Transformations, Dover, 1979] y nos proporciona una herramienta para el análisis de la perturbación. Otras aportaciones son la obtención de xpresiones explícitas para el operador inverso grupo el operador perturbado y su proyección espectral asociada al 0 y la obtención de cotas superiores para el error relativo de la inversa de Drazin y de los proyectores espectrales y un resultado de continuidad de la inversa grupo para operadores en espacios de Banach. Las aportaciones de este trabajo extienden o complementan resultados obtenidos previamente por autores sobre el mismo tema (Djordjevic, Koliha, Rakoèevic) Given a bounded operator A on a Banach space X with Drazin inverse AD and index r, we study the class of group invertible bounded operators B such that I + A(D)(B - A) is invertible and R(B) boolean AND N(A(r)) = {0}. We show that they can be written with respect to the decomposition X = R(A(r))circle plus N(A(r)) as a matrix operator, B = (B-1 B-12 B-21 B21B1-1B12), where B-1 and B-1(2) + B12B21 are invertible. Several characterizations of the perturbed operators are established, extending matrix results. We analyze the perturbation of the Drazin inverse and we provide explicit upper bounds of parallel to B-# - A(D)parallel to and parallel to BB# - A(D)A parallel to. We obtain a result on the continuity of the group inverse for operators on Banach space

Continuity of the core-EP inverse and its applications

In this paper, firstly we study the continuity of the core-EP inverse without explicit error bounds by virtue of two methods. One is the rank equality, followed from the classical generalized inverse. The other one is matrix decomposition. The continuity of the core inverse can be derived as a particular case. Secondly, we study perturbation bounds for the core-EP inverse under prescribed conditions. Perturbation bounds for the core inverse can be derived as a particular case. Also, as corollaries, the sufficient (and necessary) conditions for the continuity of the core-EP inverse are obtained. Thirdly, a numerical example is illustrated to compare derived upper bounds. Finally, an application to semistable matrices is provided.This research is supported by the National Natural Science Foundation of China (No. 11771076), partially supported by FCT-'Fundacao para a Ciencia e a Tecnologia', within the project UID-MAT-00013/2013

The condition of a finite Markov chain and perturbation bounds for the limiting probabilities

The inequalities bounding the relative error the norm of w- w squiggly/the norm of w are exhibited by a very simple function of E and A. Let T denote the transition matrix of an ergodic chain, C, and let A = I - T. Let E be a perturbation matrix such that T squiggly = T - E is also the transition matrix of an ergodic chain, C squiggly. Let w and w squiggly denote the limiting probability (row) vectors for C and C squiggly. The inequality is the best one possible. This bound can be significant in the numerical determination of the limiting probabilities for an ergodic chain. In addition to presenting a sharp bound for the norm of w-w squiggly/the norm of w an explicit expression for w squiggly will be derived in which w squiggly is given as a function of E, A, w and some other related terms

New additive results for the generalized Drazin inverse

AbstractIn this paper, we investigate additive properties of generalized Drazin inverse of two Drazin invertible linear operators in Banach spaces. Under the commutative condition of PQ=QP, we give explicit representations of the generalized Drazin inverse (P+Q)d in term of P, Pd, Q and Qd. We consider some applications of our results to the perturbation of the Drazin inverse and analyze a number of special cases