The code snippet I shared contained orthogonalization. There isn't a VecQR or VecOrthogonalize, though such a utility would be useful. Right-looking modified Gram-Schmidt would be fine for that purpose, though Cholesky QR(2) may be a bit faster.
Amneet Bhalla <mail2amn...@gmail.com> writes: > I set the rigid body null vectors but PETSc errors out that these are not > orthogonal. Is there a canned routine in PETSc to orthogonalize a bunch of > Vecs? > > [0]PETSC ERROR: Invalid argument > > [0]PETSC ERROR: Vector 0 must be orthogonal to vector 2, inner product is > 0.612391 > > [0]PETSC ERROR: See > https://urldefense.us/v3/__https://petsc.org/release/faq/__;!!G_uCfscf7eWS!ZflPyOP4IDILfa8HbHnR6mnArgOdC6dZ_mtE9devYndPR0QSR4S1__A-ax9BF-jpScXFYeYXsw3fTEv4TSk$ > for trouble shooting. > > [0]PETSC ERROR: Petsc Release Version 3.17.5, unknown > > [0]PETSC ERROR: ./acoustic_streaming_hier_integrator_2d on a darwin-dbg > named APSB-MacBook-Pro-16.local by amneetb Mon Nov 4 18:01:09 2024 > > [0]PETSC ERROR: Configure options --CC=mpicc --CXX=mpicxx --FC=mpif90 > --PETSC_ARCH=darwin-dbg --with-debugging=1 --download-hypre=1 --with-x=0 > -download-mumps -download-scalapack -download-parmetis -download-metis > -download-ptscotch > > [0]PETSC ERROR: #1 MatNullSpaceCreate() at > /Users/amneetb/Softwares/PETSc-Gitlab/PETSc/src/mat/interface/matnull.c:271 > > [0]PETSC ERROR: #2 resetMatNearNullspace() at > ../../../IBAMR/ibtk/lib/../src/solvers/impls/PETScKrylovLinearSolver.cpp:697 > > P=00000:Program abort called in file > ``../../../IBAMR/ibtk/lib/../src/solvers/impls/PETScKrylovLinearSolver.cpp'' > at line 697 > > P=00000:ERROR MESSAGE: > > P=00000: > Abort trap: 6 > > On Mon, Nov 4, 2024 at 10:11 AM Jed Brown <j...@jedbrown.org> wrote: > >> Unless the problem is entirely floating (the true null space is all six >> rigid body modes), then they will be different, so yes, you'll typically >> have two MatNullSpace objects. >> >> Amneet Bhalla <mail2amn...@gmail.com> writes: >> >> > Hi Jed, >> > >> > Do I need to create two separate MattNullSpace objects if I want to use >> > both MatSetNullSpace() and MatSetNearNullSpace()? >> > >> > Thanks, >> > >> > >> > On Thu, Oct 31, 2024 at 8:18 AM Jed Brown <j...@jedbrown.org> wrote: >> > >> >> Pierre Jolivet <pie...@joliv.et> writes: >> >> >> >> >> On 31 Oct 2024, at 2:47 PM, Mark Adams <mfad...@lbl.gov> wrote: >> >> >> >> >> >> Interesting. I have seen hypre do fine on elasticity, but do you know >> >> if boomeramg (classical) uses these vectors or is there a smoothed >> >> aggregation solver in hypre? >> >> > >> >> > I’m not sure it is precisely “standard” smoothed aggregation, see >> bottom >> >> paragraph of >> >> >> https://urldefense.us/v3/__https://hypre.readthedocs.io/en/latest/solvers-boomeramg.html*amg-for-systems-of-pdes__;Iw!!G_uCfscf7eWS!fdj4AzKhAcDmM1x_ZQ8gxqWeX6BAKY9urnvATMpT7hC8lw77ak7tqxqXGIX3PMg2wYA5PGu7EzyCW0yzixutBg$ >> >> > I’ve never made it to work, but I know some do. >> >> > A while back, Stefano gave me this pointer as well: >> >> >> https://urldefense.us/v3/__https://github.com/mfem/mfem/blob/17955e114020af340e9a06a66ebef43e05012d9c/linalg/hypre.cpp*L5245__;Iw!!G_uCfscf7eWS!fdj4AzKhAcDmM1x_ZQ8gxqWeX6BAKY9urnvATMpT7hC8lw77ak7tqxqXGIX3PMg2wYA5PGu7EzyCW0wVEi33Pw$ >> >> >> >> It's still classical AMG, and in my experience, struggles on very thin >> >> structures (e.g., aspect ratio 1000 cantilever beams) when compared to >> SA. >> >> However, it can be quite competitive for many structures. I found that >> the >> >> "MFEM elasticity suite", which is based on Baker et al 2010, gave rather >> >> poor results. This is a configuration that works on GPUs and gives good >> >> convergence and performance for elasticity: >> >> >> >> >> >> >> https://urldefense.us/v3/__https://github.com/hypre-space/hypre/issues/601*issuecomment-1069426997__;Iw!!G_uCfscf7eWS!arUVBVKKcYs1M5OhNqqRZl2b2o0NIUkG7fV_22qBbg-ssHhhHazhkpMbYNjCOTN66Sfbk-VZilfox9bxDf0$ >> >> >> >> In the above issue, I was only using BoomerAMG as a coarse level for >> p-MG >> >> so all the options have a `-mg_coarse_` prefix; here are those options >> >> without the prefix: >> >> >> >> -pc_hypre_boomeramg_coarsen_type pmis >> >> -pc_hypre_boomeramg_interp_type ext+i >> >> -pc_hypre_boomeramg_no_CF >> >> -pc_hypre_boomeramg_P_max 6 >> >> -pc_hypre_boomeramg_print_statistics 1 >> >> -pc_hypre_boomeramg_relax_type_down Chebyshev >> >> -pc_hypre_boomeramg_relax_type_up Chebyshev >> >> -pc_hypre_boomeramg_strong_threshold 0.5 >> >> -pc_type hypre >> >> >> > >> > >> > -- >> > --Amneet >> > > > -- > --Amneet
