On Wed, Jan 19, 2022 at 12:54 PM Marco Cisternino <
marco.cistern...@optimad.it> wrote:
> Thank you, Matthew.
>
> I’m going to pay attention to our non-dimensionalization, avoiding
> division by cell volume helps a lot.
>
>
>
> Sorry, Mark, I cannot get your point: which 1D problem are you referri
.
Bests,
Marco Cisternino
From: Mark Adams
Sent: mercoledì 19 gennaio 2022 15:16
To: Matthew Knepley
Cc: Marco Cisternino ; petsc-users
Subject: Re: [petsc-users] Nullspaces
ILU is LU for this 1D problem and its singular.
ILU might have some logic to deal with a singular system. Not sure. LU should
is best to choose
> length (and other) units that make the matrix entries about 1. It seems
> like you are far from this, and it is causing a loss of accuracy (your
> null vector has a residual of about 1e-7).
>
> Thanks,
>
> Matt
>
>
>> Thank you very much for
o choose
length (and other) units that make the matrix entries about 1. It seems
like you are far from this, and it is causing a loss of accuracy (your null
vector has a residual of about 1e-7).
Thanks,
Matt
> Thank you very much for your support!
>
>
>
>
>
> Marco
isternino
mailto:marco.cistern...@optimad.it>>
Sent: martedì 7 dicembre 2021 19:36
To: Matthew Knepley mailto:knep...@gmail.com>>
Cc: petsc-users mailto:petsc-users@mcs.anl.gov>>
Subject: Re: [petsc-users] Nullspaces
I will, as soon as possible...
Scarica Outlook per Andro
RRQ(ierr);
>
> With this fix, your two cases give the same answer, namely that the
> constant vector is not a null vector of your
> operator, but it is close, as your can see using -mat_null_space_test_view.
>
> Thanks,
>
> Matt
>
>
>> Thanks for any help.
>>
; Marco Cisternino, PhD
> marco.cistern...@optimad.it
>
> __
>
> Optimad Engineering Srl
>
> Via Bligny 5, Torino, Italia.
> +3901119719782
> www.optimad.it
>
>
>
> *From:* Marco Cisternino
> *Sent:* martedì 7 dicembre 2021 19:36
>
Barry Smith
Sent: mercoledì 5 gennaio 2022 23:17
To: Marco Cisternino
Cc: Jose E. Roman ; petsc-users
Subject: Re: [petsc-users] Nullspaces
What do you get for the two eigenvectors ?
> On Jan 5, 2022, at 11:21 AM, Marco Cisternino
> wrote:
>
> Hello Jose and Stefano.
> Thank
> -Original Message-
> From: Jose E. Roman
> Sent: martedì 4 gennaio 2022 19:30
> To: Marco Cisternino
> Cc: Stefano Zampini ; petsc-users
>
> Subject: Re: [petsc-users] Nullspaces
>
> To compute more than one eigenpair, call
> EPSSetDimensions(eps,
nino
-Original Message-
From: Jose E. Roman
Sent: martedì 4 gennaio 2022 19:30
To: Marco Cisternino
Cc: Stefano Zampini ; petsc-users
Subject: Re: [petsc-users] Nullspaces
To compute more than one eigenpair, call
EPSSetDimensions(eps,nev,PETSC_DEFAULT,PETSC_DEFAULT).
To compute zero eig
To compute more than one eigenpair, call
EPSSetDimensions(eps,nev,PETSC_DEFAULT,PETSC_DEFAULT).
To compute zero eigenvalues you may want to use an absolute convergence
criterion, with EPSSetConvergenceTest(eps,EPS_CONV_ABS), but then a tolerance
of 1e-12 is probably too small. You can try witho
Matthew Knepley mailto:knep...@gmail.com>>; petsc-users
mailto:petsc-users@mcs.anl.gov>>
Subject: RE: [petsc-users] Nullspaces
We usually analyze the code with valgrind, when important changes are
implemented.
I have to admit that this analysis is still not automatic and the case we ar
to
> understand something.
>
Try running slepc to find the smallest eigenvalues. There should be two
zero eigenvalues, then inspect the eigenvectors
>
>
> Thank you all.
>
>
>
> Marco Cisternino
>
>
>
> *From:* Marco Cisternino
> *Sent:* lunedì 3 gennaio 2
k Adams
Cc: Matthew Knepley ; petsc-users
Subject: RE: [petsc-users] Nullspaces
We usually analyze the code with valgrind, when important changes are
implemented.
I have to admit that this analysis is still not automatic and the case we are
talking about is not a test case for our workload.
Th
both the real code and the tiny one for this case with
valgrind and report the results.
Thank you,
Marco Cisternino
From: Mark Adams
Sent: lunedì 3 gennaio 2022 15:50
To: Marco Cisternino
Cc: Matthew Knepley ; petsc-users
Subject: Re: [petsc-users] Nullspaces
I have not looked at your code
t; Via Bligny 5, Torino, Italia.
> +3901119719782
> www.optimad.it
>
>
>
> *From:* Mark Adams
> *Sent:* lunedì 3 gennaio 2022 14:42
> *To:* Marco Cisternino
> *Cc:* Matthew Knepley ; petsc-users <
> petsc-users@mcs.anl.gov>
> *Subject:* Re: [petsc-users] Nul
Torino, Italia.
+3901119719782
www.optimad.it<http://www.optimad.it/>
From: Mark Adams
Sent: lunedì 3 gennaio 2022 14:42
To: Marco Cisternino
Cc: Matthew Knepley ; petsc-users
Subject: Re: [petsc-users] Nullspaces
There could be a memory bug that does not cause a noticeable problem until i
gt; *Sent:* sabato 25 dicembre 2021 14:59
> *To:* Marco Cisternino
> *Cc:* Matthew Knepley ; petsc-users <
> petsc-users@mcs.anl.gov>
> *Subject:* Re: [petsc-users] Nullspaces
>
>
>
> If "triggering the issue" requires a substantial mesh, that makes me
> th
My comments are between the Mark’s lines and they starts with “#”
Marco Cisternino
From: Mark Adams
Sent: sabato 25 dicembre 2021 14:59
To: Marco Cisternino
Cc: Matthew Knepley ; petsc-users
Subject: Re: [petsc-users] Nullspaces
If "triggering the issue" requires a substantial
My comments are between Barry’s lines
Marco Cisternino
From: Barry Smith
Sent: venerdì 24 dicembre 2021 23:57
To: Marco Cisternino
Cc: Matthew Knepley ; petsc-users
Subject: Re: [petsc-users] Nullspaces
I tried your code but it appears the ./gyroid_solution.txt contains a vector
of all
petsc 3.15.2(intelOneAPI) same results.
>
> If the attachment is not delivered, I can share a link to it.
>
>
>
> Thanks for any help.
>
>
>
> Marco Cisternino
>
>
>
>
>
> Marco Cisternino, PhD
> marco.cistern...@optimad.it
>
> ___
lto:marco.cistern...@optimad.it>
> __
> Optimad Engineering Srl
> Via Bligny 5, Torino, Italia.
> +3901119719782
> www.optimad.it <http://www.optimad.it/>
>
> From: Marco Cisternino <mailto:marco.cistern...@optimad.it>>
> Sent: martedì 7 d
I will, as soon as possible...
Scarica Outlook per Android<https://aka.ms/AAb9ysg>
From: Matthew Knepley
Sent: Tuesday, December 7, 2021 7:25:43 PM
To: Marco Cisternino
Cc: petsc-users
Subject: Re: [petsc-users] Nullspaces
On Tue, Dec 7, 2021 at 11:19 AM
On Tue, Dec 7, 2021 at 11:19 AM Marco Cisternino <
marco.cistern...@optimad.it> wrote:
> Good morning,
>
> I’m still struggling with the Poisson equation with Neumann BCs.
>
> I discretize the equation by finite volume method and I divide every line
> of the linear system by the volume of the cell
> for (PetscInt i = 0; i < nConstants; ++i) {
>
> VecRestoreArray(constants[i], &rawConstants[i]);
>
> VecAssemblyBegin(constants[i]);
>
> VecAssemblyEnd(constants[i]);
>
> VecNormalize(constants[i], nullptr);
>
This does not look correct.
rino, Italia.
+3901119719782
www.optimad.it<http://www.optimad.it/>
From: Barry Smith
Sent: martedì 7 dicembre 2021 17:53
To: Marco Cisternino
Cc: petsc-users
Subject: Re: [petsc-users] Nullspaces
A side note: The MatNullSpaceTest tells you that the null space you provided
is in the n
A side note: The MatNullSpaceTest tells you that the null space you provided
is in the null space of the operator, it does not say if you have found the
entire null space. In your case with two subdomains the null space is actually
two dimensional; all constant on one domain (0 on the other)
rl
Via Bligny 5, Torino, Italia.
+3901119719782
www.optimad.it<http://www.optimad.it/>
From: Mark Adams
Sent: martedì 7 dicembre 2021 17:47
To: Marco Cisternino
Cc: petsc-users
Subject: Re: [petsc-users] Nullspaces
Can you please give more details on what 'does not work' is.
Can you please give more details on what 'does not work' is.
More detail on how you judge what works would also be useful.
Mark
On Tue, Dec 7, 2021 at 11:19 AM Marco Cisternino <
marco.cistern...@optimad.it> wrote:
> Good morning,
>
> I’m still struggling with the Poisson equation with Neumann BC
Good morning,
I'm still struggling with the Poisson equation with Neumann BCs.
I discretize the equation by finite volume method and I divide every line of
the linear system by the volume of the cell. I could avoid this division, but
I'm trying to understand.
My mesh is not uniform, i.e. cells ha
I'm actually not proposing putting extra intelligence into the DM, but into
the ApplicationCtx
and the associated callbacks that the user can write. The DM is used to
propagate this information
to the deeper levels of a nested solver hierarchy by "restricting" the
relevant ctx/callbacks to the spl
Dmitry Karpeyev writes:
> I think the problem-specific solver configuration can be carried out by an
> additional user-specified callback (attached, e.g., using PCSetUserSetUp())
> called from PCSetUp().
> The problem of propagating it down the hierarchy can be solved by using DMs
> (even DMShell
On Wed Nov 12 2014 at 7:49:28 PM Jed Brown wrote:
> Barry Smith writes:
> >Perhaps we need a generic way of attaching null spaces to parts of
> >matrices and to parts of matrices in different basis (which is what
> >a Schur complement is). So (and this is likely overly simplistic)
>
Barry Smith writes:
> Indeed it could. Perhaps we could start by unifying the concept of a
> sub matrix and a Schur complement of the same part of the matrix?
> I'm not sure how to do that.
We can certainly define an interface that works this way, but I'm not
sure it's practical.
signatur
> On Nov 12, 2014, at 7:49 PM, Jed Brown wrote:
>
> Barry Smith writes:
>> Perhaps we need a generic way of attaching null spaces to parts of
>> matrices and to parts of matrices in different basis (which is what
>> a Schur complement is). So (and this is likely overly simplistic)
>> on
Barry Smith writes:
>Perhaps we need a generic way of attaching null spaces to parts of
>matrices and to parts of matrices in different basis (which is what
>a Schur complement is). So (and this is likely overly simplistic)
>one could supply a null space, an index set, and a flag i
I agree with what Jed says.
One could argue that if the matrix was represented as a MatNest, the null
space of the Schur complement is a property of the MatNest object and hence
could/should be something that is attached to the matrix. Now if the Mat
happens not to be a MatNest, the null s
Lawrence Mitchell writes:
> So is the problem that the nullspace belongs to the appropriate
> operator, but at the point you tell the solver, you don't necessarily
> have all the operators to hand? Moreover, depending on the PC choice,
> the nullspaces of the operator blocks may or may not be rel
-BEGIN PGP SIGNED MESSAGE-
Hash: SHA1
On 11/11/14 15:18, Jed Brown wrote:
...
> Matt and I have a long-running disagreement about nullspace
> handling in PETSc. He added the code that hangs it on an IS
> despite it not logically belonging on IS, simply because the
> implementation in P
Lawrence Mitchell writes:
> OK, so it's sounds like this is probably a deliberate choice. I note that
> the code currently does this:
>
> fieldsplit.c:703
>
> ierr = MatSetFromOptions(jac->schur);CHKERRQ(ierr);
> ierr = MatGetNullSpace(jac->pmat[1], &sp);CHKERRQ(ierr);
> if (sp
On Mon, Nov 10, 2014 at 10:28 PM, Jed Brown wrote:
> Matthew Knepley writes:
> >> at which point the nullspace is not attached, no?
> >>
> >
> > Crap, that is right. I think we should propagate the nullspace from
> pmat[1].
>
> Uh, there is no reason pmat[1] can be expected to have the same null
On 11 Nov 2014, at 04:28, Jed Brown wrote:
> Matthew Knepley writes:
>>> at which point the nullspace is not attached, no?
>>>
>>
>> Crap, that is right. I think we should propagate the nullspace from pmat[1].
>
> Uh, there is no reason pmat[1] can be expected to have the same null
> space.
Matthew Knepley writes:
>> at which point the nullspace is not attached, no?
>>
>
> Crap, that is right. I think we should propagate the nullspace from pmat[1].
Uh, there is no reason pmat[1] can be expected to have the same null
space. pmat[1] is the zero matrix in some important cases, and the
On Mon, Nov 10, 2014 at 5:34 PM, Lawrence Mitchell <
lawrence.mitch...@imperial.ac.uk> wrote:
>
> On 10 Nov 2014, at 21:48, Matthew Knepley wrote:
>
> > On Fri, Nov 7, 2014 at 11:04 AM, Lawrence Mitchell <
> lawrence.mitch...@imperial.ac.uk>wrote:
> > Hi petsc-dev,
> >
> > I'm solving a pure Neum
On 10 Nov 2014, at 21:48, Matthew Knepley wrote:
> On Fri, Nov 7, 2014 at 11:04 AM, Lawrence Mitchell
> wrote:
> Hi petsc-dev,
>
> I'm solving a pure Neumann mixed Poisson-like problem, preconditioning with a
> schur complement. The pressure space has a nullspace of the constant
> functions
On Fri, Nov 7, 2014 at 11:04 AM, Lawrence Mitchell <
lawrence.mitch...@imperial.ac.uk> wrote:
> Hi petsc-dev,
>
> I'm solving a pure Neumann mixed Poisson-like problem, preconditioning
> with a schur complement. The pressure space has a nullspace of the
> constant functions and so I attach the ap
Hi petsc-dev,
I'm solving a pure Neumann mixed Poisson-like problem, preconditioning with a
schur complement. The pressure space has a nullspace of the constant functions
and so I attach the appropriate nullspace to the krylov solver, and compose the
constant nullspace with the IS defining the
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