The Lanczos method for solving systems of linear equations is implemented by using some recurrence relationships between polynomials of a family of formal orthogonal polynomials or between those of two adjacent families of formal orthogonal polynomials. A division by zero can occur in these relations, thus producing a breakdown in the algorithm which has to be stopped. In this paper, three strategies to avoid this drawback are discussed: the MRZ and its variants, the normalized and unnormalized BIORES algorithm and the composite step biconjugate algorithm. We prove that all these algorithms can be derived from a unified framework; in fact, we give a formalism for finding all the recurrence relationships used in these algorithms, which shows that the three strategies use the same techniques.
@article{bwmeta1.element.bwnjournal-article-zmv26i4p477bwm, author = {A. El Guennouni}, title = {A unified approach to some strategies for the treatment of breakdown in Lanczos-type algorithms}, journal = {Applicationes Mathematicae}, volume = {26}, year = {1999}, pages = {477-488}, zbl = {0998.65042}, language = {en}, url = {http://dml.mathdoc.fr/item/bwmeta1.element.bwnjournal-article-zmv26i4p477bwm} }
El Guennouni, A. A unified approach to some strategies for the treatment of breakdown in Lanczos-type algorithms. Applicationes Mathematicae, Tome 26 (1999) pp. 477-488. http://gdmltest.u-ga.fr/item/bwmeta1.element.bwnjournal-article-zmv26i4p477bwm/
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