[petsc-users] Convert mat SEQAIJ to MPIAIJ

[Thomas Witkowski]

In my FETI-DP code, each rank creates a SEQAIJ matrix that represents 
the discretization of the interior domain. Just for debugging, I would 
like to join these sequential matrices to one global MPIAIJ matrix. This 
matrix has no off diagonal nnzs and should be stored corresponding to 
the ranks unknowns, thus, first all rows of the first rank and so on. 
What's the most efficient way to do this? Is it possible to create this 
parallel matrix just as a view of the sequential ones, so without 
copying the data? Thanks for any advise.

Thomas