In any case, I use KSPSetOperators(ksp, A, A, SAME_NONZERO_PATTERN). 1) If I provide only approximation for number of zeros per row (d_nz and o_nz) and I overshoot - will the extra memory still be there or is automatically freed?
2) Do I need to MatMPIAIJSetPreallocation() after MatZeroEntries(A)? MatZeroEntries man page says: If the matrix was not preallocated then a default, likely poor preallocation will be set in the matrix, so this should be called after the preallocation phase. A was preallocated during creation, but unless I call MatMPIAIJSetPreallocation after MatZeroEntries, I get a lot of unneded mallocs. Many thanks for any clarifications. Dominik
