On condition numbers and the distance to the nearest III-posted problem
Numerische Mathematik
Matrix computations (3rd ed.)
Perturbation of least squares problem in Hilbert spaces
Applied Mathematics and Computation
Accuracy and Stability of Numerical Algorithms
Accuracy and Stability of Numerical Algorithms
A note on level-2 condition numbers
Journal of Complexity
Computers & Mathematics with Applications
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In this paper, we present characterizations for the level-2 condition number of the weighted Moore-Penrose inverse, i.e., cond"M"N(A)@?cond"M"N^[^2^](A)@?cond"M"N(A)+1, where cond"M"N(A) is the condition number of the weighted Moore-Penrose inverse of a rectangular matrix and cond"M"N^[^2^](A) is the level-2 condition number of this problem. This paper extends the result by Cucker, Diao and Wei [F. Cucker, H. Diao, Y. Wei, On the level-2 condition number for Moore-Penrose inversion, 2005, Unpublished report] and improves the results by Wei and Wang [Y. Wei, D. Wang, Condition numbers and perturbation of weighted Moore-Penrose inverse and weighted linear least squares problem, Appl. Math. Comput. 145 (2003) 45-58].