[petsc-users] Get LU decomposition of a rectangular matrix

Tue Mar 13 10:30:53 CDT 2018

  Dang, PETSc sucks, it really shouldn't be calling MatGetOrdering() since MPAIJ can't use that information. And external packages ignore PETSc orderings anyways.

   I'll try to see why it is calling MatGetOrdering in this case.

    Barry

> On Mar 13, 2018, at 7:04 AM, Natacha BEREUX <natacha.bereux at gmail.com> wrote:
> 
> Hi Barry 
> Thanks for your answer, 
> I followed your suggestion (matrix type = MPIAIJ and superlu_dist on a single processor)   but I still get the same problem. 
> 
> 
> Rectangular matrices seem to be forbidden in MatGetOrdering(), whatever package is used for the LU decomposition
> 
> Here is the output : 
>  ./ex12f -f data/constraints.bin -pc_factor_mat_solver_package superlu_dist -pc_type lu
> 
>    9   33    9   33  1.     0.3E+02 0.3E+02  0.     0.7E+04  1.      0.    
> [0]PETSC ERROR: --------------------- Error Message --------------------------------------------------------------
> [0]PETSC ERROR: Invalid argument
> [0]PETSC ERROR: Must be square matrix, rows 33 columns 9
> [0]PETSC ERROR: See http://www.mcs.anl.gov/petsc/documentation/faq.html for trouble shooting.
> [0]PETSC ERROR: Petsc Release Version 3.8.3, Dec, 09, 2017 
> [0]PETSC ERROR: ./ex12f on a linux-debug-mumps-ml-hypre-superlu-superlu_dist named dsp0780444 by H03755 Tue Mar 13 08:57:22 2018
> [0]PETSC ERROR: Configure options --with-mpi=1 --with-debugging=1 --with-mumps-lib="-L/home/H03755/dev/codeaster-prerequisites/v14/prerequisites//Mumps-511_consortium_aster/MPI/lib -lzmumps -ldmumps -lmumps_common -lpord -L/home/H03755/dev/codeaster-prerequisites/v14/prerequisites//Parmetis_aster-403_aster/lib -lparmetis -L/home/H03755/dev/codeaster-prerequisites/v14/prerequisites//Scotch_aster-604_aster6/MPI/lib -lptscotch  -lptscotcherr  -lptscotcherrexit  -lptscotchparmetis  -lesmumps -lscotch -lscotcherr -lscotcherrexit  -L/home/H03755/dev/codeaster-prerequisites/v14/prerequisites//Metis_aster-510_aster1/lib -lmetis" --with-mumps-include=/home/H03755/dev/codeaster-prerequisites/v14/prerequisites//Mumps-511_consortium_aster/MPI/include --download-hypre=/home/H03755/Librairies/hypre-2.12.0.tar.gz --download-ml=/home/H03755/Librairies/petsc-pkg-ml-e5040d11aa07.tar.gz --with-openmp=0 --with-scalapack-lib="-lscalapack-openmpi -lblacs-openmpi -lblacsF77init-openmpi -lblacsCinit-openmpi" --with-blaslapack-lib="-llapack -lopenblas" --PETSC_ARCH=linux-debug-mumps-ml-hypre-superlu-superlu_dist LIBS=-lgomp --with-parmetis-dir=/home/H03755/dev/codeaster-prerequisites/v14/prerequisites//Parmetis_aster-403_aster --with-metis-dir=/home/H03755/dev/codeaster-prerequisites/v14/prerequisites//Metis_aster-510_aster1 --prefix=/home/H03755/local/petsc/petsc-3.8.3 --download-superlu=/home/H03755/Librairies/superlu_dist-master.zip --with-parmetis-dir=/home/H03755/dev/codeaster-prerequisites/v14/prerequisites//Parmetis_aster-403_aster --with-metis-dir=/home/H03755/dev/codeaster-prerequisites/v14/prerequisites//Metis_aster-510_aster1 --download-superlu=/home/H03755/Librairies/superlu-a0819410c9eb779f9b296cdd95fbdfd96986ae10.tar.gz
> [0]PETSC ERROR: #1 MatGetOrdering() line 243 in /home/H03755/Librairies/petsc-3.8.3/src/mat/order/sorder.c
> [0]PETSC ERROR: #2 MatGetOrdering() line 192 in /home/H03755/Librairies/petsc-3.8.3/src/mat/order/sorder.c
> [0]PETSC ERROR: #3 PCSetUp_LU() line 84 in /home/H03755/Librairies/petsc-3.8.3/src/ksp/pc/impls/factor/lu/lu.c
> [0]PETSC ERROR: #4 PCSetUp() line 924 in /home/H03755/Librairies/petsc-3.8.3/src/ksp/pc/interface/precon.c
> [0]PETSC ERROR: #5 User provided function() line 0 in User file
> 
> 
> My code looks like : 
> call MatLoad(A,fd,ierr)
> call KSPCreate(PETSC_COMM_WORLD,ksp,ierr)
> call KSPSetOperators(ksp,A,A,ierr)
> call KSPGetPC(ksp,pc,ierr)
> call PCSetFromOptions( pc, ierr) 
> call PCSetUp(pc, ierr) 
> 
> Should I call directly a factorization routine ?  Instead of trying to build a preconditionner ? 
> 
> 
> Best regards, 
> Natacha 
> 
> 
> On Mon, Mar 12, 2018 at 3:46 PM, Smith, Barry F. <bsmith at mcs.anl.gov> wrote:
> 
>    Create the matrix on one process but make it a MPIAIJ matrix (not SeqAIJ or AIJ) then you should be able to do the factorization with SuperLU_Dist
> 
>     Please let us know how it goes,
> 
>     Barry
> 
> 
> > On Mar 12, 2018, at 4:35 AM, Natacha BEREUX <natacha.bereux at gmail.com> wrote:
> >
> > Dear Petsc user's
> >
> > I am trying to use SuperLU_dist to compute LU decomposition of a non-square matrix.
> >
> > My purpose is to build a basis of the nullspace of a matrix C . This matrix stores constraints (i.e. linear relationships between degrees of freedom): it is thus rectangular (size 9 x 33) and not square
> > I need to get the L U factors of C^T which is a tall skinny matrix.
> > It is possible when using directly SuperLu or SuperLU_dist
> > But when I use Petsc interface to SuperLU I get the following error :
> >
> > [0]PETSC ERROR: Invalid argument
> > [0]PETSC ERROR: Must be square matrix, rows 9 columns 33
> > [0]PETSC ERROR: See http://www.mcs.anl.gov/petsc/documentation/faq.html for trouble shooting.
> > [0]PETSC ERROR: Petsc Release Version 3.8.3, Dec, 09, 2017
> > [0]PETSC ERROR: #1 MatGetOrdering() line 243 in /home/H03755/Librairies/petsc-3.8.3/src/mat/order/sorder.c
> > [0]PETSC ERROR: #2 PCSetUp_LU() line 84 in /home/H03755/Librairies/petsc-3.8.3/src/ksp/pc/impls/factor/lu/lu.c
> > [0]PETSC ERROR: #3 PCSetUp() line 924 in /home/H03755/Librairies/petsc-3.8.3/src/ksp/pc/interface/precon.c
> > [0]PETSC ERROR: #4 KSPSetUp() line 381 in /home/H03755/Librairies/petsc-3.8.3/src/ksp/ksp/interface/itfunc.c
> > [0]PETSC ERROR: #5 KSPSolve() line 612 in /home/H03755/Librairies/petsc-3.8.3/src/ksp/ksp/interface/itfunc.c
> > [0]PETSC ERROR: #6 User provided function() line 0 in User file
> >
> > The use of non-square matrices is forbidden.
> >
> > Is there a way to specify that I want to use a rectangular matrix ? How can I proceed to call SuperLU through PETSc with a rectangular matrix ?
> >
> > Thanks a lot for your help
> > Best regards,
> >
> > Natacha
> 
> 