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Is use of Mirror Boundary with Box Stencil supported for 2D?
by Macneice, Peter J. (GSFC-6740) 19 Feb '26

19 Feb '26

>From my searching of the documentation, it looks to me as though this combination should work. However for my modified version of the ex66.c tutorial code, I get the error message below. Is this really not yet supported? Regards Peter MacNeice [0]PETSC ERROR: --------------------- Error Message -------------------------------------------------------------- [0]PETSC ERROR: No support for this operation for this object type [0]PETSC ERROR: Mirror boundary and box stencil [0]PETSC ERROR: WARNING! There are unused option(s) set! Could be the program crashed before usage or a spelling mistake, etc! [0]PETSC ERROR: Option left: name:-dm_view (no value) source: command line [0]PETSC ERROR: Option left: name:-ksp_monitor (no value) source: command line [0]PETSC ERROR: See https://urldefense.us/v3/__https://petsc.org/release/faq/__;!!G_uCfscf7eWS!… for trouble shooting. [0]PETSC ERROR: PETSc Release Version 3.24.3, Jan 01, 2026 [0]PETSC ERROR: ex66_9pt with 1 MPI process(es) and PETSC_ARCH arch-darwin-c-debug on gs67-5186361 by pmacneic Thu Feb 19 21:03:16 2026 [0]PETSC ERROR: Configure options: --with-mpi-dir=/Users/pmacneic/mpich-install-3.3-gcc15 --force [0]PETSC ERROR: #1 DMSetUp_DA_2D() at /Users/pmacneic/petsc-3.24.3/src/dm/impls/da/da2.c:212 [0]PETSC ERROR: #2 DMSetUp_DA() at /Users/pmacneic/petsc-3.24.3/src/dm/impls/da/dareg.c:17 [0]PETSC ERROR: #3 DMSetUp() at /Users/pmacneic/petsc-3.24.3/src/dm/interface/dm.c:807 [0]PETSC ERROR: #4 main() at ex66_9pt.c:77 [0]PETSC ERROR: PETSc Option Table entries: [0]PETSC ERROR: -dm_view (source: command line) [0]PETSC ERROR: -ksp_monitor (source: command line) [0]PETSC ERROR: ----------------End of Error Message -------send entire error message to petsc-maint(a)mcs.anl.gov---------- application called MPI_Abort(MPI_COMM_SELF, 56) - process 0 Macneice, Peter J. (GSFC-6740)

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Re: [petsc-users] DG methods in PETSc
by Mark Adams 19 Feb '26

19 Feb '26

please keep this on the list. On Thu, Feb 19, 2026 at 9:36 AM Matteo Leone <matteo4.leone(a)mail.polimi.it> wrote: > Hello, I now have tested quite a bit the code, and I have some doubts. > Note I am quite new to PETSc. > > I have modified a bit your code to test it and I tried to print from the > functions to check if they were actually called with negative results. > The Riemann solver is never called and also the solution is just static in > time. > This was a work in progress, but it does run: ./ex9 -dm_plex_box_faces 8,8 -dm_plex_dim 2 -dm_plex_simplex 0 -order 1 -ts_max_steps 10 -ts_monitor -velocity 1.0,0.5 I see that the Riemann solver is set: PetscCall(PetscDSSetRiemannSolver(ds, 0, RiemannSolver_Advection)); I would not recommend using DG because there are no tests for it. There are tests for PetscDSSetRiemannSolver that you could clone and replace the FE/FV construction in those with DG: src/ts/tutorials/ex11.c: PetscCall(PetscDSSetRiemannSolver(prob, 0, user->model->physics->riemann)); src/ts/tutorials/ex18.c: if (user->velocityDist == VEL_ZERO) PetscCall(PetscDSSetRiemannSolver(prob, 1, riemann_advection)); src/ts/tutorials/ex18.c: else PetscCall(PetscDSSetRiemannSolver(prob, 1, riemann_coupled_advection)); If you get this far, you might want to look at internal examples (not tests) and clone these DG constructors: src/dm/dt/fe/interface/fe.c: PetscFECreateBrokenElement - Create a discontinuous version of the input `PetscFE` src/dm/dt/fe/interface/fe.c:PetscErrorCode PetscFECreateBrokenElement(PetscFE cgfe, PetscFE *dgfe) src/dm/impls/plex/plexcreate.c: PetscCall(PetscFECreateBrokenElement(fe, &dgfe)); src/dm/interface/dmcoordinates.c: PetscCall(PetscFECreateBrokenElement(feLinear, &dgfe)); Sorry we do not have DG fully deployed yet. Good luck, Mark > I share the code. It's a bit modified and no more c but c++ (I do not know > to write the csv file fom c, in case is a dealbreaker I'll try to give a > look on how to do it). > (For reference I use PETSc 3.24.4 by means of nix, the nix flake is in the > shared docs if you are used to it lmk). > > There is also a small .py to handle the visualization (It was made by > Claude code, but it just plots the results) > Hopefully we can go deep into this PETSc DG stuff. > > > Thanks in advace. > Matteo > > > ------------------------------ > *Da:* Mark Adams <mfadams(a)lbl.gov> > *Inviato:* mercoledì 11 febbraio 2026 17:25 > *A:* Matteo Leone <matteo4.leone(a)mail.polimi.it>; PETSc users list < > petsc-users(a)mcs.anl.gov> > *Oggetto:* Re: [petsc-users] DG methods in PETSc > > Great, and keep it on the list. Lots of people here to help! > > On Wed, Feb 11, 2026 at 9:46 AM Matteo Leone <matteo4.leone(a)mail.polimi.it> > wrote: > > Wow thank you so much! I was almost hopeless, I'll deep dive into it and > I'll give you a feedback. > > Matteo > > ------------------------------ > *From:* Mark Adams <mfadams(a)lbl.gov> > *Sent:* Wednesday, February 11, 2026 3:38:30 PM > *To:* Matteo Leone <matteo4.leone(a)mail.polimi.it> > *Cc:* petsc-users(a)mcs.anl.gov <petsc-users(a)mcs.anl.gov> > *Subject:* Re: [petsc-users] DG methods in PETSc > > DG (discontinuous Galerkin) is done with a "Broken" FE. Yikes I do not see > a test. > Here is a test but it is not well verified. > Mark > > On Tue, Feb 10, 2026 at 10:25 AM Matteo Leone via petsc-users < > petsc-users(a)mcs.anl.gov> wrote: > > Hello, I already posted on Reddit but just to be sure I write even here. > > First thanks for the job you do for PETSc, I have used it for several > projects and is always nice. > > I am writing cause I am getting mad trying to implement DG solver in > PETSc, the target is the Euler equations, however I am failing even with > just the simplest transport equation (u/t + u/x = 0). I was wondering if I > am missing somenthing. I tried with the DSSetReimannSolver and DualSpaces, > and more, but I keep failing, I tried also with LLMs, but seems like there > is no DG code with PETSc on the web, however I see many papers that do it. > > I was wondering if I am maybe missing something out or what. > > For reference I use PETSc 3.24.3 by means of nix. > > Thanks in advance, cheers. > > Matteo > >

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Limiting the number of vectors allocated at a time by fgmres etc.
by Wells, David 17 Feb '26

17 Feb '26

Hello, I've been profiling the memory usage of my solver and it looks like a huge number (roughly half) of allocations are from KSPFGMRESGetNewVectors(). I read through the source code and it looks like these vectors are allocated ten at a time (FGMRES_DELTA_DIRECTIONS) in a couple of places inside that KSP. Is there a way to change this value? If not - how hard would it be to add an API to set a different initial value for that? These vectors take up a lot of memory and I would rather just one at a time. Best, David Wells

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2026 Colorado Conference on Iterative and Multigrid Methods, June 21-26 in Boulder, CO
by Jed Brown 14 Feb '26

14 Feb '26

As Scott announces below, the conference formerly known as Copper will be held in Boulder this June. The student paper competition abstract deadline is Feb 18, with paper submission a week later. We'll have an affordable on-campus housing option. We look forward to your student paper submissions. Registration and lodging will be available soon. https://urldefense.us/v3/__https://coloradoconference.github.io/2026/__;!!G… -------------------- Start of forwarded message -------------------- From: Scott Maclachlan via SIAM <Mail(a)ConnectedCommunity.org> Date: Fri, 6 Feb 2026 17:44:03 +0000 Subject: SIAG on Computational Science and Engineering Community: 2026 Colorado Conference on Iterative and Multigrid Methods To: jed(a)jedbrown.org The Copper Mountain Conference on Multigrid Methods was founded in 1983 and held every two years (odd years) since then. In 1990, the Copper Mountain Conference on Iterative Methods was formed as a companion conference to be held in even years. Together, they are widely regarded as premier international conferences on iterative and multigrid methods. In 2026, we continue this conference series with the Colorado Conference on Iterative and Multigrid Methods to be held on the CU Boulder campus. Abstract submission for the conference will soon open, including for the student paper competition (a tradition at the meeting with a cash award). For more information, see our website at https://urldefense.us/v3/__https://coloradoconference.github.io/2026/__;!!G… Updates will be provided on the web site and in follow-up announcements in the coming weeks. Don't forget to mark your calendars! Important Deadlines: Student Paper Competition (no extensions): Abstract: Wednesday, February 18, 2026 Paper (reserved for students who submit an abstract): Wednesday, February 25, 2026 Presentation Abstracts: Friday, April 3, 2026 Early Registration: Friday, April 17, 2026 ------------------------------ Scott MacLachlan Memorial University of Newfoundland, Canada ------------------------------ Reply to Sender : https://urldefense.us/v3/__https://engage.siam.org/eGroups/PostReply/?Group… Reply to Discussion : https://urldefense.us/v3/__https://engage.siam.org/eGroups/PostReply/?Group… You are subscribed to "SIAG on Computational Science and Engineering Community" as jed(a)jedbrown.org. To change your subscriptions, go to https://urldefense.us/v3/__http://siam.connectedcommunity.org/preferences?s… . To unsubscribe from this community discussion, go to https://urldefense.us/v3/__https://siam.connectedcommunity.org/HigherLogic/… . -------------------- End of forwarded message --------------------

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Scalability
by SCOTTO Alexandre 13 Feb '26

13 Feb '26

Dear PETSc community, I have conducted a quick strong scalability-like test on direct and adjoint matrix-vector product with a 25,000 x 25,000 sparse matrix, distributed over 2, 4, ..., 32 and 64 processes and the results I obtained were not so great. I am not very confident in my setup, so a as a matter of reference, is there any available results on weak and strong scalability of PETSc.Mat mult() and multTranspose() operations? Best regards, Alexandre.

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Port existing GMRES+ILU(0) implementation to GPU
by feng wang 13 Feb '26

13 Feb '26

Dear All, I have an existing implementation of GMRES with ILU(0), it works well for cpu now. I went through the Petsc documentation, it seems Petsc has some support for GPUs. is it possible for me to run GMRES with ILU(0) in GPUs? Many thanks for your help in advance, Feng

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DMplex periodicity type
by Matteo Semplice 12 Feb '26

12 Feb '26

Dear all, regarding the two possible ways to represent periodic meshes in DMPlex (https://urldefense.us/v3/__https://petsc.org/release/manual/dmplex/*__;Iw!!… ), I have noticed that when reading in a GMSH mesh, the periodic topology is created. Is there a way to read in a mesh and create instead the non-periodic topology&local-to-global-map kind of mesh? Or, is it possible to convert between the two approaces (i.e. generate a DMPlex that is a quasi-clone of a given one, but ready for the other kind of periodicity handling)? Bets regards Matteo -- Prof. Matteo Semplice Università degli Studi dell’Insubria Dipartimento di Scienza e Alta Tecnologia – DiSAT Professore Associato Via Valleggio, 11 – 22100 Como (CO) – Italia tel.: +39 031 2386316

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PETSc Online BoF — February 11, 2026 (Free Registration)
by Junchao Zhang 11 Feb '26

11 Feb '26

Dear PETSc community, PETSc will host a free online Birds-of-a-Feather (BoF) session on *February 11, 2026*, from *10:00–11:30 am (Central Time, US and Canada)*. The BoF will not be recorded. The agenda is available at https://urldefense.us/v3/__https://petsc.org/release/community/bofs/2026_Fe… Please register in advance at https://urldefense.us/v3/__https://argonne.zoomgov.com/meeting/register/ay4… To receive a Zoom link, the organizer requires all participants to register individually. Registration is quick and requires only your name and email address. We look forward to your participation and to a productive and engaging discussion. Thank you, Junchao Zhang On behalf of the PETSc team

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Re: [petsc-users] DG methods in PETSc
by Mark Adams 11 Feb '26

11 Feb '26

Great, and keep it on the list. Lots of people here to help! On Wed, Feb 11, 2026 at 9:46 AM Matteo Leone <matteo4.leone(a)mail.polimi.it> wrote: > Wow thank you so much! I was almost hopeless, I'll deep dive into it and > I'll give you a feedback. > > Matteo > > ------------------------------ > *From:* Mark Adams <mfadams(a)lbl.gov> > *Sent:* Wednesday, February 11, 2026 3:38:30 PM > *To:* Matteo Leone <matteo4.leone(a)mail.polimi.it> > *Cc:* petsc-users(a)mcs.anl.gov <petsc-users(a)mcs.anl.gov> > *Subject:* Re: [petsc-users] DG methods in PETSc > > DG (discontinuous Galerkin) is done with a "Broken" FE. Yikes I do not see > a test. > Here is a test but it is not well verified. > Mark > > On Tue, Feb 10, 2026 at 10:25 AM Matteo Leone via petsc-users < > petsc-users(a)mcs.anl.gov> wrote: > > Hello, I already posted on Reddit but just to be sure I write even here. > > First thanks for the job you do for PETSc, I have used it for several > projects and is always nice. > > I am writing cause I am getting mad trying to implement DG solver in > PETSc, the target is the Euler equations, however I am failing even with > just the simplest transport equation (u/t + u/x = 0). I was wondering if I > am missing somenthing. I tried with the DSSetReimannSolver and DualSpaces, > and more, but I keep failing, I tried also with LLMs, but seems like there > is no DG code with PETSc on the web, however I see many papers that do it. > > I was wondering if I am maybe missing something out or what. > > For reference I use PETSc 3.24.3 by means of nix. > > Thanks in advance, cheers. > > Matteo > >

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Error when configuring PETSc with CUDA on Windows
by Dr. Milan Pelletier 11 Feb '26

11 Feb '26

Dear PETSc team, I am currently trying to upgrade my PETSc package on Windows to 3.24.4, and I'm facing issues when configuring with CUDA. Unfortunately, I cannot clearly see the error that causes the configure process to bail out Please find enclosed the configure.log file. My laptop setup: * OS: Windows 11 23H2 (if that helps, running "uname -a" in Cygwin yields: "CYGWIN_NT-10.0-22631 MPLL-PC2 3.6.6-1.x86_64 2026-01-09 17:39 UTC x86_64 Cygwin") * CPU: Intel Core i7-1370P * RAM: 32 GB * MPI: Intel oneAPI MPI * Compiler: MSVC v19.44.35222 * CUDA toolkit v13.1 Please let me know if some information is missing. Many thanks for your help, Kind regards, Dr. Milan Pelletier

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