Trying to solve many "one-dimensional" problems each in parallel on
different subset of ranks will be massive pain to do specifically. I recommend
just forming a single matrix for all these systems and solving it with KSPSolve
and block Jacobi preconditioning or even a parallel direct
Feimi,
I'm able to reproduce the problem. I will have a look. Thanks a lot for
the example.
--Junchao Zhang
On Fri, Aug 20, 2021 at 2:02 PM Feimi Yu wrote:
> Sorry, I forgot to destroy the matrix after the loop, but anyway, the
> in-loop preconditioners are destroyed. Updated the code here
Viktor --
As a basic comment, note that ILU can be used in parallel, namely on each
processor block, by either non-overlapping domain decomposition:
-pc_type bjacobi -sub_pc_type ilu
or with overlap:
-pc_type asm -sub_pc_type ilu
See the discussion of block Jacobi and ASM at
Sorry, I forgot to destroy the matrix after the loop, but anyway, the
in-loop preconditioners are destroyed. Updated the code here and the
google drive.
Feimi
On 8/20/21 2:54 PM, Feimi Yu wrote:
Hi Barry and Junchao,
Actually I did a simple MPI "dup and free" test before with Spectrum
Hi Barry and Junchao,
Actually I did a simple MPI "dup and free" test before with Spectrum
MPI, but that one did not have any problem. I'm not a PETSc programmer
as I mainly use deal.ii's PETSc wrappers, but I managed to write a
minimal program based on petsc/src/mat/tests/ex98.c to reproduce
Mark's suggestion will definitely help a lot. Remove the displacement
bc equations or include them in the matrix by zeroing out the row and
putting a 1 on the diagonal. The Lagrange multiplier will cause grief.
On 8/20/21 11:21 AM, Mark Adams wrote:
Constraints are a pain with
Constraints are a pain with scalable/iterative solvers. If you order the
constraints last then ILU should work as well as it can work, but AMG gets
confused by the constraint equations.
You could look at PETSc's Stokes solvers, but it would be best if you could
remove the constrained equations
Maybe too much fill-in during factorization. Try using an external linear
solver such as MUMPS as explained in section 3.4.1 of SLEPc's users manual.
Jose
> El 20 ago 2021, a las 16:12, Matthew Knepley escribió:
>
> On Fri, Aug 20, 2021 at 6:55 AM dazza simplythebest
> wrote:
> Dear Jose,
Dear Sir/Madam,
I am trying to use the petsc4py to solve AX = B parallelly, where A
is a large dense matrix. The Elemental package in petsc4py is very suitable for
the dense matrix, but I can't find any example or learning material about it on
the PETSc website and other websites.
On Fri, Aug 20, 2021 at 7:53 AM Joauma Marichal <
joauma.maric...@uclouvain.be> wrote:
> Dear Sir or Madam,
>
> I am looking for advice regarding some of PETSc functionnalities. I am
> currently using PETSc to solve the Navier-Stokes equations on a 3D mesh
> decomposed over several processors.
On Fri, Aug 20, 2021 at 6:55 AM dazza simplythebest
wrote:
> Dear Jose,
> Many thanks for your response, I have been investigating this issue
> with a few more calculations
> today, hence the slightly delayed response.
>
> The problem is actually derived from a fluid dynamics problem, so to
Feimi, if it is easy to reproduce, could you give instructions on how to
reproduce that?
PS: Spectrum MPI is based on OpenMPI. I don't understand why it has the
problem but OpenMPI does not. It could be a bug in petsc or user's code.
For reference counting on MPI_Comm, we already have petsc
Dear Sir or Madam,
I am looking for advice regarding some of PETSc functionnalities. I am
currently using PETSc to solve the Navier-Stokes equations on a 3D mesh
decomposed over several processors. However, until now, the processors are
distributed along the x and z directions but not along
*Hello, dear PETSc team!*
I have a 3D elasticity with heterogeneous properties problem. There is
unstructured grid with aspect ratio varied from 4 to 25. Dirichlet BCs
(bottom zero displacements) are imposed via linear constraint equations
using Lagrange multipliers. Also, Neumann (traction)
Dear Jose,
Many thanks for your response, I have been investigating this issue with a
few more calculations
today, hence the slightly delayed response.
The problem is actually derived from a fluid dynamics problem, so to allow an
easier exploration of things
I first downsized the resolution
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