The sum of two φS orthogonal matrices when S−TS is normal and −1 ∈/ σ(S−TS)

Let a nonsingular S ∈ Mn (C) be given. For A ∈ Mn (C), set φS (A) = S−1AT S. We say that A is φS symmetric if φS (A) = A; we say that A is φS orthogonal if A ∈ GLn and φS (A) = A−1; we say that A has a φS polar decomposition if A = UP for some φS orthogonal U and φS symmetric P. Suppose that S−T S i...

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Bibliographic Details
Main Author: Granario, Daryl Q.
Format: text
Published: Animo Repository 2016
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Online Access:https://animorepository.dlsu.edu.ph/faculty_research/11360
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Institution: De La Salle University
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Summary:Let a nonsingular S ∈ Mn (C) be given. For A ∈ Mn (C), set φS (A) = S−1AT S. We say that A is φS symmetric if φS (A) = A; we say that A is φS orthogonal if A ∈ GLn and φS (A) = A−1; we say that A has a φS polar decomposition if A = UP for some φS orthogonal U and φS symmetric P. Suppose that S−T S is normal and −1 ∈/ σ S−T S. We determine conditions on A ∈ Mn (C) so that A can be written as a sum of two φS orthogonal matrices.