[Trilinos-Users] Having Different Row maps and A Transposition : What To Do ?

[Davood Ansari]

Hi all

Besides assembling my *A* and *B*  matrices (as in *A *x* = *lambda* B *y
for an FE eigen-problem)
a third (constraints) matrix is needed to be assembled (call this one *C*).

For A and B, I have opted for the *usual* linearly sliced row map.
For C, the assembling process is much different (kind of recursive) from
ordinary FE matrices. Yet, there is a natural map that can partition *C*'s
rows into independent
slices. In the Solver stage, it is needed to multiply the transpose of
*C*many times
(like A and B)  with the vectors that are constructed based on the
*usual*row map.

Now, which one is possibly the right way to go:

Option I.
1.Assemble *C*, using its natural map, thus requiring no off process
communications (requires Epetra_Crs_Matrix).
2.Then, transform *C* into a new matrix which is the transpose of *C* and
complies to the *usual* map(don't even know how)

Option II.
1.Assemble *C*, using the *usual* map, thus requiring off process
communications (definitely Epetra_FECrs_Matrix)
2.Then transpose it.

Kindly comment on this
Davood
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