MatCreateMPIAIJ(), MatCreateMPIBAIJ(), MatCreateMPISBAIJ() actually create Seq version of the matrices when run on one process. Meanwhile MatMPIXXXSetPreallocation() always do preallocation for MPI case. Shouldn't MatCreateMPIXXX() be MatCreateXXX()? Also should we add MatXXXSetPreallocation() that calls both MatSeqXXXSetPreallocation() and MatMPIXXXSetPreallocation()? Barry