Yaoyu: "MatGetSubMatrices() can extract ONLY sequential submatrices (from both sequential and parallel matrices). Use MatGetSubMatrix() to extract a parallel submatrix."
Using parallel IS for MatGetSubMatrices() definitely incorrect, unless you only use one process. > > And further. I checked the submatrices I obtained by > MatGetSubMatrices() with both parallel ISs and sequential ISs. The > submatrices are identical. Is it means that I could actually use > parallel IS (created with PETSC_COMM_WORLD) ? > What did you compare with? I do not understand what submatrices would obtain with parallel IS using more than one process. Hong > > > Yaoyu : > > MatGetSubMatrices() returns sequential matrices. > > IS must be sequential, created with PETSC_COMM_SELF. > > See petsc/src/mat/examples/tests/ex42.c > > > > Check your submatrices. > > > > Hong > > > > 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 > >> > > -------------- next part -------------- > > An HTML attachment was scrubbed... > > URL: < > http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20160413/6be45909/attachment.html > > > > > > ------------------------------ > > > > _______________________________________________ > > petsc-users mailing list > > [email protected] > > https://lists.mcs.anl.gov/mailman/listinfo/petsc-users > > > > > > End of petsc-users Digest, Vol 88, Issue 41 > > ******************************************* >
