Accurate modal perturbation in non-self-adjoint eigenvalue problem

This paper presents an algorithm for the accurate modal perturbation analysis in the non-self-adjoint eigenvalue problem. Complete perturbation items are obtained from the given straightforward process, satisfying two conditions in a modal analysis: the eigenvalue equations and normality condition. The zeroth-order perturbation, solved from equations in a form of Rayleigh quotient, is employed in the later perturbations, which helps to improve the accuracy of analysis. Two examples are given to show the modal perturbation with distinct eigenvalues and with close eigenvalues. It is confirmed that the algorithm is applicable to any mode with a distinct eigenvalue, repeated eigenvalues, or close eigenvalues, and can give an improved accuracy. Copyright (C) 2001 John Wiley & Sons, Ltd.