Full length article: Asymptotic diagonalization of matrix systems

  • Authors:
  • R. J. Kooman

  • Affiliations:
  • -

  • Venue:
  • Journal of Approximation Theory
  • Year:
  • 2013

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Abstract

In recent years many results have been obtained on the asymptotic behavior of solutions of the matrix difference equation M"nx"n=x"n"+"1 where {M"n}"n"="0^~ is a sequence of kxk-matrices with real or complex entries that are close to diagonal matrices. In this paper we study the question of how to transform a matrix sequence {M"n}"n"="0^~ where the entries behave sufficiently regularly, into a sequence of almost-diagonal matrices, so that the results for almost-diagonal matrices can be applied to the difference equation with the transformed sequence. In particular, we will try to find explicit matrices B"n such that the matrices M"n^'=B"n"+"1^-^1M"nB"n are close to diagonal matrices and a Levinson-type theorem can be applied to transform the sequence {M"n^'}"n"="0^~ into a sequence of diagonal matrices. In the case that the M"n are real 2x2-matrices, a fairly general answer is obtained and it is shown how to proceed for a given sequence {M"n}"n"="0^~. Furthermore, we prove a couple of results that are useful for the case of general order k.