Remarks on condition numbers and optimally conditioned matrices

Matrix condition numbers are proved to be submultiplicative but neither subadditive nor superadditive, and the Frobenius and the default (based on the 2-norm) condition numbers are shown to be unitarily invariant. The equality of all the singular values of a square matrix is established as a necessa...

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Bibliographic Details
Main Authors: Estalilla, Aliento V., Pinpin, Lord Kenneth M.
Format: text
Published: Animo Repository 2005
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Online Access:https://animorepository.dlsu.edu.ph/faculty_research/12784
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Institution: De La Salle University
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Summary:Matrix condition numbers are proved to be submultiplicative but neither subadditive nor superadditive, and the Frobenius and the default (based on the 2-norm) condition numbers are shown to be unitarily invariant. The equality of all the singular values of a square matrix is established as a necessary and sufficient condition for the matrix to be optimally conditioned under the 2-norm, making unitary, Hadamard and some diagonal and antidiagonal matrices possess unity condition numbers.