with MatGetRow() that seems to work but it
is some lame I am even embarrased of sharing with the list what I have
Any suggestion is welcome.
ply this matrix by
> the solution vector you will get a "short" vector that on each process
> contains the "reaction" for each each of the "removed row" on that process.
> Easy to implement.
> > On Oct 19, 2016, at 4
re is something wrong with your matrix. Use any solver and
> verify that you like the solution first.
> On Fri, Oct 28, 2016 at 9:13 AM, Jeremy Theler <jer...@seamplex.com>
> Hi! I want to use PCGAMG as a preconditioner for a 3D linear
> If I do not call PCSetCoordinates() the error goes away but
> is slow.
> Is it possible that your coordinates lie on a 2D surface? All this
> does is make the 6 basis vectors
> for translations and rotations. You can just make these yourself and
Hi! I want to use PCGAMG as a preconditioner for a 3D linear elasticity
problem (displacement-based FEM formulation) over an unstructured grid.
I am not using DMPlex, I just build the stiffness matrix myself and pass
it to PETSc.
I set MatSetBlockSize() to 3 and pass the node coordinates through
On Fri, 2016-10-28 at 09:46 -0400, Mark Adams wrote:
> Please run with -info and grep on GAMG.
 PCSetUp_GAMG(): level 0) N=120726, n data rows=3, n data cols=6,
nnz/row (ave)=41, np=1
 PCGAMGFilterGraph(): 99.904% nnz after filtering, with
threshold 0., 13.7468 nnz ave. (N=40242)
On Mon, 2016-10-31 at 08:44 -0600, Jed Brown wrote:
> > After understanding Matt's point about the near nullspace (and reading
> > some interesting comments from Jed on scicomp stackexchange) I did built
> > my own vectors (I had to take a look at MatNullSpaceCreateRigidBody()
> > because I found
> elements badly stretched?
> Do this again with these parameters:
> -mg_levels_ksp_type chebyshev
> -mg_levels_esteig_ksp_type cg
> -mg_levels_esteig_ksp_max_it 10
> -mg_levels_ksp_chebyshev_esteig 0,.1,0,1.05
> -gamg_est_ksp_type cg
> On Fri,
I once made a quick hack, maybe you can start your dirty work from here
On Tue, Oct 11, 2016 at 5:31 PM Barry Smith wrote:
when I ask
MatGetNearNullSpace(matrix) passing the problem matrix after setting
PCSetCoordinates(pc) I get:
error: PETSc error 85-0 'Null Object: Parameter # 1'
that describes the methods and not just the implementation as
the source code at gamg/util.c so I can better understand what is going
On Thu, 2017-01-05 at 09:18 -0500, Mark Adams wrote:
> You want the bottom of page 84 in the manual.
> On W
Hi! Any reference to what does -pc_gamg_threshold mean and/or?
* Any reference to what pc_gamg_treshold means and/or does?
On Wed, 2017-01-04 at 18:13 -0300, Jeremy Theler wrote:
> Hi! Any reference to what does -pc_gamg_threshold mean and/or?
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