Use of near-breakdowns in the block Arnoldi method for solving large Sylvester equations

  • Authors:
  • M. Robbé;M. Sadkane

  • Affiliations:
  • Département de Mathématiques, Université de Brest, 6, avenue Le Gorgeu, CS 93837, 29238 Brest cedex 3, France;Département de Mathématiques, Université de Brest, 6, avenue Le Gorgeu, CS 93837, 29238 Brest cedex 3, France

  • Venue:
  • Applied Numerical Mathematics
  • Year:
  • 2008

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Abstract

In this paper we construct an approximate solution to large Sylvester equations of the form AX+XB=CD^T. The construction uses a new variant of the block Arnoldi algorithm which exploits the near-breakdowns, that is, the near singularities in the generated basis. As a consequence, the algorithm eliminates the directions which do not contribute to the approximate solution by keeping in the generated basis only the ''active'' vectors detected by a criterion based on the residual associated with the approximate solution. The effectiveness of the proposed algorithm is demonstrated on several examples, including the case where the matrix B has a small or a large size.