Hi Barry,
I need some help on the parallel version of MatBAIJBlockDiagonalScale. My
understanding is that MatBAIJBlockDiagonalScale_MPIBAIJ would be a wrapper
on the MatBAIJBlockDiagonalScale_SeqBAIJ. However, I am not clear about how
to get the local part of MPIBAIJ. Does the local part of
Thanks a lot, Barry! I see that you had implemented the bs=3 special case.
I will play with these codes and add at least bs=2 case and try to get it
working for parallel baij. I will let you know the update.
Thank you.
Xiangdong
On Wed, Feb 14, 2018 at 2:57 PM, Smith, Barry F.
In the PETSc git branch barry/feature-baij-blockdiagonal-scale I have done
the "heavy lifting" for what you need. See
https://bitbucket.org/petsc/petsc/branch/barry/feature-baij-blockdiagonal-scale
It scales the Seq BAIJ matrix by its block diagonal. You will need to write a
routine to
The idea goes back to the alternate-block-factorization (ABF) method
https://link.springer.com/article/10.1007/BF01932753
and is widely used in the reservoir simulation, where the unknowns are
pressure and saturation. Although the coupled equations are parabolic, the
pressure equations/variables
Hmm, I never had this idea presented to me, I have no way to know if it is
particularly good or bad. So essentially you transform the matrix "decoupling
the physics alone the diagonal" and then do PCFIELDSPLIT instead of using
PCFIELDSPLIT directly on the original equations.
Maybe in the
The reason for the operation invdiag(A)*A is to have a decoupled
matrix/physics for preconditioning. For example, after the transformation,
the diagonal block is identity matrix ( e.g. [1,0,0;0,1,0;0,0,1] for
bs=3). One can extract a submatrix (e.g. corresponding to only first
unknown) and apply
In general you probably don't want to do this. Most good preconditioners (like
AMG) rely on the matrix having the "natural" scaling that arises from the
discretization and doing a scaling like you describe destroys that natural
scaling. You can use PCPBJACOBI to use point block Jacobi
Hello everyone,
I have a block sparse matrices A created from the DMDA3d. Before passing
the matrix to ksp solver, I want to apply a transformation to this matrix:
namely A:= invdiag(A)*A. Here invdiag(A) is the inverse of the block
diagonal of A. What is the best way to get the transformed
