Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Structure-preserving diagonalization of matrices in indefinite inner
  product spaces   In this work some results on the structure-preserving diagonalization of
selfadjoint and skewadjoint matrices in indefinite inner product spaces are
presented. In particular, necessary and sufficient conditions on the symplectic
diagonalizability of (skew)-Hamiltonian matrices and the perplectic
diagonalizability of per(skew)-Hermitian matrices are provided. Assuming the
structured matrix at hand is additionally normal, it is shown that any
symplectic or perplectic diagonalization can always be constructed to be
unitary. As a consequence of this fact, the existence of a unitary,
structure-preserving diagonalization is equivalent to the existence of a
specially structured additive decomposition of such matrices. The implications
of this decomposition are illustrated by several examples.

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The categories of this paper are: hep-ph
7
The categories of this paper are: hep-th
20
The categories of this paper are: acc-phys
12
The categories of this paper are: nucl-th
32
The categories of this paper are: atom-ph
15
The categories of this paper are: nucl-ex
31
The categories of this paper are: ao-sci
18
The categories of this paper are: econ
17
The categories of this paper are: q-fin
24
The categories of this paper are: dg-ga
4
The categories of this paper are: cond-mat
22
The categories of this paper are: chao-dyn
9
The categories of this paper are: nlin
33
The categories of this paper are: plasm-ph
25
The categories of this paper are: patt-sol
30
The categories of this paper are: q-alg