EigenSystem fails to converge

*To*: mathgroup at smc.vnet.net*Subject*: [mg93841] EigenSystem fails to converge*From*: "Adel Elsabbagh" <aelsabbagh at gmail.com>*Date*: Thu, 27 Nov 2008 05:27:55 -0500 (EST)

Dear Mathematica professionals, I have a system which I am trying to find its N lowest eigenvalues and vectors using the function: [l,u] = EigenSystem[{K,M},-N]; K and M are quite large matrices in the order of 1000*1000, and whose entries are complex numbers. The Eigensystem function works fine most of the time. However, sometimes it gives me the following error for no reason that I know: Eigensystem::cfail : Algorithm failed to converge. Are there any options/methods for Eigensystem that I can choose and which will allow the convergence? Kind regards, -- Adel Elsabbagh http://www.svlab-asu.com/aelsabbagh.html