[petsc-users] Preallocation Memory of Finite Element Method's Sparse Matrices

[Jed Brown]

Barry Smith <bsmith at mcs.anl.gov> writes:

>   Thank you for reporting this. It was our error. In fact 4 is not
>   enough under certain circumstances; consider where each process has
>   only a single degree of freedom (vertex) then it is coupled to 8
>   other vertices ALL on other processes. Thus we really need to use 8
>   instead of 4 as the maximum number of off process coupling.

Note that _your_ code should generally not have this problem because you
should use a non-pathological partition.
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