[petsc-users] Problem when getting matrix values owned by other processor

[Yaoyu Hu]

Hi everyone,

I am trying to get values owned by other processors of a parallel matrix.

I tried to create a sub-matrix by using MatGetSubMatrices(), and then
MatGetRow() on the sub-matrix. But MatGetRow() give me the following
error message:

===== Error message begins =====

No support for this operation for this object type
only local rows

===== Error message ends =====

The parallel matrix is a parallel dense matrix. The ISs for
MatGetSubMatrices() are created using ISCreateGeneral() and
PETSC_COMM_WORLD. The row IS is sorted by ISSort().

What did I mistake while using the above functions? Is there a better
way to get access to matrix values owned by other processor?

Thanks!

HU Yaoyu