[Trilinos-Users] question about an arbitrary Tpetra::map

Wen Yan wenyan4work at gmail.com
Fri Nov 22 10:52:57 EST 2019

Dear Trilinos users,

Could you please help me understand this constructor of Tpetra::map?

If I want to have a (row or column) map for a Tpetra::CrsMatrix, like this:
Index:   [0, 1,  2,  3,  4,  5, 6, 7, 8,  9]
Owner: [X, X, 0, 0/1, X, 1, X, X,1, 0/1]
where the mathematical dimension is 10, indexbase=0, distributed on two
ranks (0 and 1), and X means no rank owns this index, i.e., no entry in the
sparse matrix.
rank 0 owns indices 2,3,9
rank 1 owns indices 3,5,8,9

Question 1:
Is it correct to construct this map with the following parameters?
indexList = [2,3,9] on rank0, and [3,5,8,9] on rank1,
indexListSize= 3 on rank0, and 4 on rank1.

Question 2:
I am particularly confused by the document of indexBase, which says: "
Currently, Map
 requires that this equal the global minimum index over all processes'
indexList inputs."
Does this mean that index 0 must be owned by some rank, even if there is no
entry for this index? Further, does this mean every globalIndex in a
Tpetra::map must be owned by some rank?

Thank you,
*Wen Yan*
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