Leung, Andrew Yee TakAndrew Yee TakLeung2022-05-202022-05-201990https://repository.sfu.edu.hk/handle/sfu/3260The most general case of perturbation of a repeated eigenvalue of a derogatory eigenproblem is considered. It is shown that Puiseux expansions of the perturbed eigensolutions are inevitable in the degenerated case where the Taylor expansions are erroneous.enjournal article10.1002/cnm.1630060511