Dear petsc,
I need to hand-code a jacobian and I can't figure out how to
translate the DMplex points/fields to matrix indices.
My DMPlex has a section with m fields per cell (which makes for n>m dof
per cell since some fields are vector). Say I want to insert an nxn
block for the row corresponding to cell c and coloumn of its neighbour
d. I guess that I should call either MatSetValues/MatSetValuesLocal or
the blocked variants, but how do I find the row/col indices to pass in
starting from the c/d dmplex points? And, while I am at it, which
MatSetValues version standard/Local standard/blocked is best?
I looked for a petsc example, but fails to find it: if there's one, can
you just point me to it?
Thanks in advance.
Matteo Semplice
