[petsc-users] Allocating the diagonal for MatMPIAIJSetPreallocation

Samuel Estes samuelestes91 at gmail.com
Fri Apr 1 11:26:59 CDT 2022


I have a problem in which I know (roughly) the number of non-zero entries
for each row of a matrix but I don't have a convenient way of determining
whether they belong to the diagonal or off-diagonal part of the parallel
matrix. Is there some way I can just allocate the total number of non-zeros
in a row regardless of which part they belong to? I'm assuming that this is
not possible but I just wanted to check. It seems like it should be
possible in principle since the matrix is only split by the rows but the
columns of a row are all on the same processor (at least as I understand
it). Thanks!

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