On Green's Matrices of Trees

نویسنده

  • Reinhard Nabben
چکیده

The inverse C = [ci,j ] of an irreducible nonsingular symmetric tridiagonal matrix is a socalled Green’s matrix, i.e. it is given by two sequences of real numbers {ui} and {vi} such that ci,j = uivj for i ≤ j. A similar result holds for nonsymmetric matrices. An open problem on nonsingular sparse matrices is whether there exists a similar structure for their inverses as in the tridiagonal case. Here we positively answer this question for acyclic matrices, i.e. matrices whose undirected graphs are trees. We prove that the inverses of acyclic symmetric matrices are given as the Hadamard product of three matrices, a type D matrix, a flipped type D matrix and a matrix of tree structure which is closely related to the graph of the original matrix itself. For nonsymmetric matrices we obtain a similar structure. Moreover, our result include the result for symmetric and nonsymmetric tridiagonal matrices.

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عنوان ژورنال:
  • SIAM J. Matrix Analysis Applications

دوره 22  شماره 

صفحات  -

تاریخ انتشار 2001