Will a call to MatZeroEntries
and MatAssemblyBegin/End(mat,MAT_FINAL_ASSEMBLY) do same as
MatSetValues() with zero values?
Michael.
On 06/29/2015 02:38 PM, Barry Smith wrote:
On Jun 29, 2015, at 1:28 PM, Michael Povolotskyi <[email protected]> wrote:
Thank you.
Is there a way to disable the squeeze?
Not directly (it won't know what to do with the empty space). If you want to insure that a
sparse matrix has a particular nonzero structure then just set values of 0.0 into the
"extra" locations you want represented in the "nonzero pattern". One simple
way to do this is call MatSetValues() for the nonzero structure you want with all zero entries,
then call MatAssemblyBegin/End(mat,MAT_FINAL_ASSEMBLY) and then call MatSetValues() to put the
numerical values you want to set (which will be a subset of the location you put in with zeros)
then call MatAssemblyBegin/End(mat,MAT_FINAL_ASSEMBLY) again.
Barry
Michael.
On 06/29/2015 01:58 PM, Barry Smith wrote:
On Jun 29, 2015, at 10:49 AM, Michael Povolotskyi <[email protected]> wrote:
Dear developers,
I have the following question:
Imagine that I have two matrices A and B
Both are created using MatCreateSeqAIJ(MPI_Comm comm,PetscInt m,PetscInt
n,PetscInt nz,const PetscInt nnz[],Mat *A)
with the same first 5 arguments.
In addition, for both matrices I call
MatSetOption(A,MAT_NEW_NONZERO_ALLOCATION_ERR,PETSC_TRUE);
After this I set some entries to both A and B matrices and assemble them.
Question: can I use MatAXPY with SAME_NONZERO_PATTERN argument?
Only if you KNOW that they have the exact same nonzero pattern. The MatAssembly
"squeezes" out any "extra" space that was preallocated but was not actually
used when calling MatSetValues() so even if two matrices have the same preallocation it doesn't
mean they have the same nonzero pattern.
Barry
Thank you,
Michael.
--
Michael Povolotskyi, PhD
Research Assistant Professor
Network for Computational Nanotechnology
Hall for Discover and Learning Research, Room 441
West Lafayette, IN 47907
Phone (765) 4949396
--
Michael Povolotskyi, PhD
Research Assistant Professor
Network for Computational Nanotechnology
Hall for Discover and Learning Research, Room 441
West Lafayette, IN 47907
Phone (765) 4949396
