On 17.05.2011, at 04:54, Matthew Knepley wrote: > Anecdotally, I hear that XFEM can produce ill-conditioned matrices, where the > conditioning arises from geometric factors. I don't think you can > a priori rule out differences in conditioning as the process count increases > which come from changing geometry of the interface. > > Matt
Anyway, the ill-conditoning should not be a problem here. Luckily, a diagonal scaling does a great job to improve the condition number. And as you said while the ill-conditioning usually arises from geometric factors I can identify the XFEM degrees of freedom which account for the ill-conditioning. Blocking such DOFs carefully also improves the condition number, which I usually not do as the diagonal scaling already leads to a condition number in the order of the standard FEM matrix. Henning
