On Tue, Mar 28, 2023 at 12:38 PM Blaise Bourdin wrote:
>
>
> On Mar 27, 2023, at 9:11 PM, Mark Adams wrote:
>
> Yes, the eigen estimates are converging slowly.
>
> BTW, have you tried hypre? It is a good solver (lots lots more woman years)
> These eigen estimates are conceptually simple, but
This suite has been good for my solid mechanics solvers. (It's written here as
a coarse grid solver because we do matrix-free p-MG first, but you can use it
directly.)
https://github.com/hypre-space/hypre/issues/601#issuecomment-1069426997
Blaise Bourdin writes:
> On Mar 27, 2023, at 9:11
On Mar 27, 2023, at 9:11 PM, Mark Adams wrote:
Yes, the eigen estimates are converging slowly.
BTW, have you tried hypre? It is a good solver (lots lots more woman years)
These eigen estimates are conceptually simple, but they can lead to problems like this (hypre and an
Yes, the eigen estimates are converging slowly.
BTW, have you tried hypre? It is a good solver (lots lots more woman years)
These eigen estimates are conceptually simple, but they can lead to
problems like this (hypre and an eigen estimate free smoother).
But try this (good to have options
Try -pc_gamg_reuse_interpolation 0. I thought this was disabled by default, but
I see pc_gamg->reuse_prol = PETSC_TRUE in the code.
Blaise Bourdin writes:
> On Mar 24, 2023, at 3:21 PM, Mark Adams wrote:
>
> * Do you set:
>
> PetscCall(MatSetOption(Amat, MAT_SPD, PETSC_TRUE));
>
>
On Mar 24, 2023, at 3:21 PM, Mark Adams wrote:
* Do you set:
PetscCall(MatSetOption(Amat, MAT_SPD, PETSC_TRUE));
PetscCall(MatSetOption(Amat, MAT_SPD_ETERNAL, PETSC_TRUE));
Yes
Do that to get CG Eigen estimates.
* Do you set:
PetscCall(MatSetOption(Amat, MAT_SPD, PETSC_TRUE));
PetscCall(MatSetOption(Amat, MAT_SPD_ETERNAL, PETSC_TRUE));
Do that to get CG Eigen estimates. Outright failure is usually caused by a
bad Eigen estimate.
-pc_gamg_esteig_ksp_monitor_singular_value
Will print out the
You can -pc_gamg_threshold .02 to slow the coarsening and either stronger
smoother or increase number of iterations used for estimation (or increase
tolerance). I assume your system is SPD and you've set the near-null space.
Blaise Bourdin writes:
> Hi,
>
> I am having issue with GAMG for
Hi,
I am having issue with GAMG for some very ill-conditioned 2D linearized
elasticity problems (sharp variation of elastic moduli with thin regions of
nearly incompressible material). I use snes_type newtonls, linesearch_type cp,
and pc_type gamg without any further options. pc_type Jacobi
Mark, should we provide some more flexible way to label fields? It
will be more complicated than the present code and I think packing into
interlaced format is faster anyway.
I'm thinking this would entail reordering the matrix and inverting this
permutation for the fine grid R P. This
Stephan, I have pushed a pull request to fix this but for now you can just
use -mg_levels_ksp_type chebyshev -mg_levels_pc_type jacobi. This used to
be the default be we move to SOR recently.
Mark
On Sat, Mar 29, 2014 at 5:52 PM, Mark Adams mfad...@lbl.gov wrote:
Sorry for getting to this
On 01/04/14 16:07, Mark Adams wrote:
Stephan, I have pushed a pull request to fix this but for now you can just
use -mg_levels_ksp_type chebyshev -mg_levels_pc_type jacobi. This used to
be the default be we move to SOR recently.
Mark
Ah, that's great news. Thanks a lot for the effort. You're
Stephan Kramer s.kra...@imperial.ac.uk writes:
Yes indeed. I've come to realize this now by looking into how smoothed
aggregation with a near null space actually works. We currently have
our dofs numbered the wrong way around (vertices on the inside,
velocity component on the outside - which
Sorry for getting to this late. I think you have figured it out basically
but there are a few things:
1) You must set the block size of A (bs=2) for the null spaces to work and
for aggregation MG to work properly. SA-AMG really does not make sense
unless you work at the vertex level, for which
On 21/03/14 11:34, Stephan Kramer wrote:
On 21/03/14 04:24, Jed Brown wrote:
Stephan Kramer s.kra...@imperial.ac.uk writes:
We have been having some problems with GAMG on petsc-dev (master) for
cases that worked fine on petsc 3.4. We're solving a Stokes equation
(just the velocity block) for
On 21/03/14 04:24, Jed Brown wrote:
Stephan Kramer s.kra...@imperial.ac.uk writes:
We have been having some problems with GAMG on petsc-dev (master) for
cases that worked fine on petsc 3.4. We're solving a Stokes equation
(just the velocity block) for a simple convection in a square box
Hi guys,
We have been having some problems with GAMG on petsc-dev (master) for cases that worked fine on petsc 3.4. We're solving a Stokes equation (just the velocity block) for a simple convection in a square
box (isoviscous). The problem only occurs if we supply a near null space (via
Stephan Kramer s.kra...@imperial.ac.uk writes:
We have been having some problems with GAMG on petsc-dev (master) for
cases that worked fine on petsc 3.4. We're solving a Stokes equation
(just the velocity block) for a simple convection in a square box
(isoviscous). The problem only occurs if
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