Abstract
We are considering modifications of the higher-order interval Schulz methods for improving an initial inclusion for the inverse of a matrix. It is proved that the methods are strictly monotone in both bounds if this is the case for the first iteration step. A necessary and sufficient condition for the existence of such an initial inclusion is given as well as an easy-to-compute formula for it.
Zusammenfassung
Wir betrachten in dieser Note Modifikationen der intervallmäßigen Schulz-Verfahren höherer Ordnung zur Verbesserung einer Einschließung für die Inverse einer Matrix. Es wird ein Satz über das in beiden Schranken streng monotone Verhalten der Methoden bewiesen. Eine notwendige und hinreichende Bedingung für die Existenz solch einer Anfangseinschließung wird angegeben sowie solch eine Intervallmatrix auch berechnet.
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Dedicated to Professor Dr. G. Hämmerlin on the occasion of his 60th birthday
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Herzberger, J. On the monotonicity of higher-order interval iterations for bounding the inverse matrix. Computing 40, 367–372 (1988). https://doi.org/10.1007/BF02276921
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DOI: https://doi.org/10.1007/BF02276921