[petsc-users] MatGetSubMatrices or VecCreateGhost

[Bikash Kanungo]

Hi,

I need to multiply a matrix A with several vectors v_i's and use the
resultant vectors in my calculation which involves access to non-local
nodes. I can think of two possible ways to do it:

1. Store the vectors v_i's into an MPIDENSE matrix and perform MatMatMult
with A to get a resultant dense matrix B. I can now use MatGetSubMatrices
on B to access the non-local part required in my subsequent calculations.

2. Use MatMult to evaluate A*v_i for each of the vectors and provide ghost
padding through VecCreateGhost for the resultant vector.

Which of the two is a more efficient way to perform the task? Also, if
there is a better way possible to achieve the same, then kindly let me know.

Thanks,
Bikash

-- 
Bikash S. Kanungo
PhD Student
Computational Materials Physics Group
Mechanical Engineering
University of Michigan
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