Normal matrices
This paper gives 70 equivalent conditions for the normality of a square matrix A that involve polynomials, matrix equations, commutativity, invariant subspaces, Hermitian and skew-Hermitian parts of A and their eigenvalues, the polar factors of A and their eigenvalues, the singular values of A, trace formulas, pencil eigenvalues, the Moore-Penrose inverse, inner product equations, the field of values and more. A short discussion of proofs and references follows.
scientific article; zbMATH DE number 3991706
scientific article