Hi, if I do not specify any preconditioner, is one used by default? If so, which one? I am using the DMDA 3d context and petsc3.3-p2. Thank you, Michele -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20120905/c719e99f/attachment.html>