Eigenvalues of the sum of matrices from unitary similarity orbits

Chi Kwong Li, Yiu Tung Poon, Nung Sing Sze

Research output: Journal article publicationJournal articleAcademic researchpeer-review

4 Citations (Scopus)


Let A and B be n x n complex matrices. Characterization is given for the set ∈{A, B) of eigenvalues of matrices of the form U * AU + V * BV for some unitary matrices U and V, Consequences of the results are discussed and computer algorithms and programs are designed to generate the set ∈(A, B). The results refine those of Wielandt on normal matrices. Extensions of the results to the sum of matrices from three or more unitary similarity orbits are also considered.
Original languageEnglish
Pages (from-to)560-581
Number of pages22
JournalSIAM Journal on Matrix Analysis and Applications
Issue number2
Publication statusPublished - 1 Dec 2008
Externally publishedYes


  • Davis-Wielandt shell
  • Eigenvalues
  • Sum of matrices
  • Unitary similarity orbits

ASJC Scopus subject areas

  • Analysis


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