Rayleigh–Ritz eigenvalue estimates for Hermitian matrices obey Cauchy interlacing, which has helpful implications for theory, applications, and algorithms. In contrast, few results about the Ritz values of non-Hermitian matrices are known, beyond their containment within the numerical range. To show that such Ritz values enjoy considerable structure, we establish regions within the numerical ra...

This paper concerns the Rayleigh–Ritz method for computing an approximation to an eigenspace X of a general matrix A from a subspace W that contains an approximation to X . The method produces a pair (N, X̃) that purports to approximate a pair (L,X), where X is a basis for X and AX = XL. In this paper we consider the convergence of (N, X̃) as the sine of the angle between X andW approaches zero. ...

We make use of the Pad e approximants and Krylov's sequence x; Ax; ; : : :; A m?1 x in the projection methods to compute a few Ritz values of a hermitian matrix A of order n. This process consists of approaching the poles of R x () = ((I ?A) ?1 x; x), the mean value of the resolvant of A, by those of m ? 1=m] Rx (), where m ? 1=m] Rx () is the Pad e approximant of order m of the function R x ()...

We derive error bounds for the Rayleigh-Ritz method for the approximation to extremal eigenpairs of a symmetric matrix. The bounds are expressed in terms of the eigenvalues of the matrix and the angle between the subspace and the eigenvector. We also present a sharp bound.

In the present study, buckling problem of nonhomogeneous microbeams with a variable cross-section is analyzed. The microcolumn considered in this study made functionally graded materials longitudinal direction and varies continuously throughout axial direction. Bernoulli–Euler beam theory conjunction modified strain gradient are employed to model structure by considering size effect. Rayleigh–R...

We consider a parallel method for solving generalized eigenvalue problems that arise from molecular orbital calculation of the biochemistry application. Our focus is to develop scalable parallel implementations of the method that achieves high performance on multi-core clusters. In a Rayleigh-Ritz type method using a contour integral (CIRR method), the computation at each contour involves linea...