[petsc-users] direct solver question

[Barry Smith]

On Aug 7, 2012, at 12:06 PM, Tabrez Ali <stali at geology.wisc.edu> wrote:

> Hello list
> 
> By any chance is using
> 
> -ksp_type gmres -pc_type lu
> 
> similar to
> 
> -ksp_type preonly -pc_type lu?
> 
> Should the results be equivalent?
> 
> T

   The should be similar but will not be identical necessarily, in particular when the matrix is ill conditioned they can be very different and in fact GMRES may iterate a few times.

   Barry