18 citations · 38 across the 8 of their papers we have counts for
9 papers
Perturbation of eigenvalues of the Klein-Gordon operators
Ivica Nakić, Krešimir Veselić
We prove inclusion theorems for both spectra and essential spectra as well as two-sided bounds for isolated eigenvalues for Klein-Gordon type Hamiltonian operators. We first study…
Spectral gap estimates for some block matrices
Ivan Veselic, Kresimir Veselic
We estimate the size of the spectral gap at zero for some Hermitian block matrices. Included are quasi-definite matrices, quasi-semidefinite matrices (the closure of the set of the…
The TAN Theorem for Indefinite Quadratic Forms
Luka Grubišić, Vadim Kostrykin, Konstantin A. Makarov +1
A version of the Davis-Kahan Tan theorem [SIAM J. Numer. Anal. \textbf{7} (1970), 1 -- 46] for not necessarily semibounded linear operators defined by quadratic forms is prove…
Representation Theorems for Indefinite Quadratic Forms Revisited
Luka Grubisic, Vadim Kostrykin, Konstantin A. Makarov +1
The first and second representation theorems for sign-indefinite, not necessarily semi-bounded quadratic forms are revisited. New straightforward proofs of these theorems are given…
Modal approximations to damped linear systems
K. Veseli/'c
We consider a finite dimensional damped second order system and obtain spectral inclusion theorems for the related quadratic eigenvalue problem. The inclusion sets are the 'quasi C…
Spectral perturbation bounds for selfadjoint operators
K. Veselic
We give general spectral and eigenvalue perturbation bounds for a selfadjoint operator perturbed in the sense of the pseudo-Friedrichs extension. We also give several generalisatio…