Geodesic
Low-rank perturbations of symmetric matrices and their condensed forms under unitary congruences
Žurnal vyčislitelʹnoj matematiki i matematičeskoj fiziki, Tome 49 (2009) no. 4, pp. 595-600 
M. Ghasemi Kamalvand; Kh. D. Ikramov. Low-rank perturbations of symmetric matrices and their condensed forms under unitary congruences. Žurnal vyčislitelʹnoj matematiki i matematičeskoj fiziki, Tome 49 (2009) no. 4, pp. 595-600. http://geodesic.mathdoc.fr/item/ZVMMF_2009_49_4_a0/
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     title = {Low-rank perturbations of symmetric matrices and their condensed forms under unitary congruences},
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     url = {http://geodesic.mathdoc.fr/item/ZVMMF_2009_49_4_a0/}
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Voir la notice de l'article provenant de la source Math-Net.Ru

The method MINRES-CN was earlier proposed by the authors for solving systems of linear equations with conjugate-normal coefficient matrices. It is now shown that this method is also applicable even if the coefficient matrix, albeit not conjugate-normal, is a low-rank perturbation of a symmetric matrix. If the perturbed matrix is still conjugate-normal, then, starting from some iteration step, the recursion underlying MINRES-CN becomes a three-term relation. These results are proved in terms of matrix condensed forms with respect to unitary congruences.

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