In the present work, numerical methods are used to analyze random one-dimensional tight binding models. In physical terms, these models describe a quantum particle (\electron") which moves along a one-dimensional chain ...

We survey some results concerning the problem of finding the complex hermitian matrix or matrices of least supremum norm with variable diagonal. Some qualitative general results are given and more specific descriptions are ...

We obtain new bounds for the entries of the inverse of a diagonally-dominant tridiagonal matrix which improve the best previous ones, due to H.-B. Li et al. We apply our bounds to the tridiagonal matrices arising in the ...

The problem of joint approximate diagonalization of symmetric real matrices is addressed. It is reduced to an optimization problem with the restriction that the matrix of the similarity transformation is orthogonal. ...

We study certain pairs of subspaces V and W of C^n we call supports that consist of eigenspaces of the eigenvalues ±‖M‖ of a minimal hermitian matrix M(‖M‖ ≤‖M+D‖ for all real diagonals D). For any pair of orthogonal ...

We study the C* -algebra D+K which consists of sums of a diagonal plus a compact operator. We describe the structure of the unitary group, the sets of ideals, automorphisms and projections.

Given a Hermitian matrix M ∈ M3(ℂ) we describe explicitly the real diagonal matrices DM such that ║M + DM║ ≤ ║M + D║ for all real diagonal matrices D ∈ M3(ℂ), where ║ · ║ denotes the operator norm. Moreover, we generalize ...