Abstract: A short review of some methods for calculating eigenvector derivatives is presented in this paper, in which the Fox-method (and improved Fox-method), Nelson-method (and improved Nelson-method), Fox's modal method, and currently advanced complete modal method as well as matrix perturbation method are concerned with. Based on the review, an improved modal method is proposed in the paper. This method possesses some merits, such as that it can make use of banded-state property of coefficient matrix in the governing equation for eigenvector derivatives to increase the efficiency of computation and needs only the modes corresponding to the eigenvalue under consideration. The present method has some formats, but only a principal format, which possesses much better precision, is described in the paper. Finally it is pointed out that the improved modal method reveals the inner relationship between Nelson-method and modal method.

Key words: eigenvector derivative, modal combinatory method, sensitivity analysis