You basically need the inverse of MatCreateSubmatrices(). I do not think we have that right now, but it could probably be done without too much trouble by looking at that code.
Thanks, Matt On Tue, Feb 19, 2019 at 6:15 AM Marius Buerkle via petsc-users < petsc-users@mcs.anl.gov> wrote: > Hi ! > > Is there some way to combine MatCompositeMerge > with MatCreateRedundantMatrix? I basically want to create copies of a > matrix from PETSC_COMM_WORLD to subcommunicators, do some work on each > subcommunicator and than gather the results back to PETSC_COMM_WORLD, > namely I want to sum the the invidual matrices from the subcommunicatos > component wise and get the resulting matrix on PETSC_COMM_WORLD. Is this > somehow possible without going through all the hassle of using MPI > directly? > > marius > -- What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead. -- Norbert Wiener https://www.cse.buffalo.edu/~knepley/ <http://www.cse.buffalo.edu/~knepley/>