Since mumps and scalapack are already installed on my computer, I only ran ./configure with --download-superlu_dist .
After everything is done, I received the error: dyld: lazy symbol binding failed: Symbol not found: _MatSolverTypeRegister_SuperLU_DIST Referenced from: /Users/yaxiong/Downloads/petsc-3.9.4/arch-darwin-c-debug/lib/libpetsc.3.9.dylib Expected in: flat namespace dyld: Symbol not found: _MatSolverTypeRegister_SuperLU_DIST Referenced from: /Users/yaxiong/Downloads/petsc-3.9.4/arch-darwin-c-debug/lib/libpetsc.3.9.dylib Expected in: flat namespace [0]PETSC ERROR: ------------------------------------------------------------------------ [0]PETSC ERROR: Caught signal number 5 TRAP [0]PETSC ERROR: Try option -start_in_debugger or -on_error_attach_debugger [0]PETSC ERROR: or see http://www.mcs.anl.gov/petsc/documentation/faq.html#valgrind [0]PETSC ERROR: or try http://valgrind.org on GNU/linux and Apple Mac OS X to find memory corruption errors [0]PETSC ERROR: likely location of problem given in stack below [0]PETSC ERROR: --------------------- Stack Frames ------------------------------------ [0]PETSC ERROR: Note: The EXACT line numbers in the stack are not available, [0]PETSC ERROR: INSTEAD the line number of the start of the function [0]PETSC ERROR: is given. [0]PETSC ERROR: [0] MatInitializePackage line 150 /Users/yaxiong/Downloads/petsc-3.9.4/src/mat/interface/dlregismat.c [0]PETSC ERROR: [0] MatCreate line 83 /Users/yaxiong/Downloads/petsc-3.9.4/src/mat/utils/gcreate.c [0]PETSC ERROR: --------------------- Error Message -------------------------------------------------------------- [0]PETSC ERROR: Signal received ________________________________ From: Smith, Barry F. <bsm...@mcs.anl.gov> Sent: Tuesday, February 5, 2019 10:58 PM To: Yaxiong Chen Cc: petsc-users@mcs.anl.gov Subject: Re: [petsc-users] PETSC matrix assembling super slow Run ./configure with --download-superlu_dist --download-mumps --download-scalapack and the you can use either -pc_factor_mat_solver_type superlu_dist or -pc_factor_mat_solver_type mumps Good luck > On Feb 5, 2019, at 9:29 PM, Yaxiong Chen <chen2...@purdue.edu> wrote: > > > Also, I found the solving time is also shorter when I use the direct > > solver(0.432s vs 4.332 s ). Is this due the small scale of the system? > > When I have a very large (e.g., 100000*100000 ) system, can I expect > > iterative solver being faster? > > << It sounds like the default preconditioner is not working well on your > problem. First run with -ksp_monitor -ksp_converged_reason to get an idea of > how quickly <<the iterative solver is converging. If the number of iterations > is high you are going to need to change the preconditioner to get one that > converges well for your <<problem. What mathematical models is your code > implementing, this will help in determining what type of preconditioner to > use. > > << Barry > > > It seems I can only work with Jacobi pre-conditioner. When I try LU or > Cholesky ,I got the error : > [0]PETSC ERROR: See > http://www.mcs.anl.gov/petsc/documentation/linearsolvertable.html for > possible LU and Cholesky solvers > [0]PETSC ERROR: Could not locate a solver package. Perhaps you must > ./configure with --download-<package> > [0]PETSC ERROR: See http://www.mcs.anl.gov/petsc/documentation/faq.html for > trouble shooting. > [0]PETSC ERROR: Petsc Release Version 3.9.4, Sep, 11, 2018 > [0]PETSC ERROR: ./optimal_mechanical_part.hdc on a arch-darwin-c-debug named > hidac.ecn.purdue.edu by chen2018 Tue Feb 5 22:19:08 2019 > [0]PETSC ERROR: Configure options > [0]PETSC ERROR: #1 MatGetFactor() line 4328 in > /Users/yaxiong/Downloads/petsc-3.9.4/src/mat/interface/matrix.c > [0]PETSC ERROR: #2 PCSetUp_Cholesky() line 86 in > /Users/yaxiong/Downloads/petsc-3.9.4/src/ksp/pc/impls/factor/cholesky/cholesky.c > [0]PETSC ERROR: #3 PCSetUp() line 923 in > /Users/yaxiong/Downloads/petsc-3.9.4/src/ksp/pc/interface/precon.c > [0]PETSC ERROR: #4 KSPSetUp() line 381 in > /Users/yaxiong/Downloads/petsc-3.9.4/src/ksp/ksp/interface/itfunc.c > [0]PETSC ERROR: #5 KSPSolve() line 612 in > /Users/yaxiong/Downloads/petsc-3.9.4/src/ksp/ksp/interface/itfunc.c > solve time 3.8589999999985025E-003 > reason 0 > It asks me to download the package. Do I want to run the command in the > folder of PETSC? But I am not sure what the name of the package should be . I > tried with ./configure --download-<PCLU> But it does not work. > > From: Smith, Barry F. <bsm...@mcs.anl.gov> > Sent: Tuesday, February 5, 2019 1:18 PM > To: Yaxiong Chen > Cc: PETSc users list > Subject: Re: [petsc-users] PETSC matrix assembling super slow > > > > > On Feb 5, 2019, at 10:32 AM, Yaxiong Chen <chen2...@purdue.edu> wrote: > > > > Thanks Barry, > > I will explore how to partition for parallel computation later. But > > now I still have some confusion on the sequential operation. > > I compared PETSC and Mumps. In both case, the subroutine for generating > > elemental matrix is very similar. However, the difference is in the > > following step： > > call MatSetValues(Amat,ne,idx,ne,idx,Ae,ADD_VALUES,ierr) > > In this step ,each element cost about 3~4 e-2 second. > > > > However, when I use mumps, I use the following code: > > preA(Aptr+1:Aptr+n*(n+1)/2) = pack(Ae, mask(1:n,1:n)) > > Aptr = Aptr +n*(n+1)/2 > > if (allocated(auxRHSe)) preRHS(idx) = preRHS(idx)+auxRHSe > > It just cost 10e-6~10e-5 second. For a 10000*10000 matrix, the assembling > > time for using PETSC is 300s while it cost 60s when using Mumps. > > For a 10000*10000 system,the Is there any way I can make it faster? > > As we keep saying the slowness of the matrix assembly is due to incorrect > preallocation. Once you have the preallocation correct the speed should > increase dramatically. > > > Also, I found the solving time is also shorter when I use the direct > > solver(0.432s vs 4.332 s ). Is this due the small scale of the system? > > When I have a very large (e.g., 100000*100000 ) system, can I expect > > iterative solver being faster? > > It sounds like the default preconditioner is not working well on your > problem. First run with -ksp_monitor -ksp_converged_reason to get an idea of > how quickly the iterative solver is converging. If the number of iterations > is high you are going to need to change the preconditioner to get one that > converges well for your problem. What mathematical models is your code > implementing, this will help in determining what type of preconditioner to > use. > > Barry > > > > > > Thanks > > > > Yaxiong > > > > > > > > > > > > Yaxiong Chen, > > Ph.D. Student > > > > School of Mechanical Engineering, 3171 > > 585 Purdue Mall > > West Lafayette, IN 47907 > > > > > > > > > > > > From: Smith, Barry F. <bsm...@mcs.anl.gov> > > Sent: Monday, February 4, 2019 10:42 PM > > To: Yaxiong Chen > > Cc: PETSc users list > > Subject: Re: [petsc-users] PETSC matrix assembling super slow > > > > > > > > > On Feb 4, 2019, at 4:41 PM, Yaxiong Chen <chen2...@purdue.edu> wrote: > > > > > > Hi Barry, > > > > > > !=================================================== > > > mystart =rank +1 ! rank starts > > > from 0 > > > do i=mystart,nelem,nproc ! nelem: total number > > > of elements ; nproc :number of process > > > call ptSystem%getElementalMAT(i, Ae, auxRHSe, idx) ! > > > Generate elemental matrix Ae and corresponding global Idx > > > ne=size(idx) > > > idx=idx-1 !-1 since PETSC index starts from zero > > > if (allocated(auxRHSe)) call > > > VecSetValues(bvec,ne,idx,auxRHSe,ADD_VALUES,ierr) > > > call MatSetValues(Amat,ne,idx,ne,idx,Ae,ADD_VALUES,ierr) ! > > > Add elemental RHS to global RHS > > > end do > > > !=================================================== > > > Maybe this is where I am wrong. The way I use MPI is to let each core > > > generate the elemental matrix in turn. > > > > This is very bad strategy because there is no data locality. > > > > > Which means I have one global matrix on each core and finally add them > > > together. My case is similar to typical finite element method. But the > > > problem is the Index is not continuous, in this case I don't know how I > > > can partition the global matrix. Do you have any suggestions or do you > > > have any template which can show me how finite element method use PETSC? > > > > What you need to do is partition the elements across the processors (so > > that the each process has a contiguous subdomain of elements), The each > > process computes the element stiffness for "its elements". There really > > isn't a single PETSc example that manages this all directly for finite > > elements because that is a rather involved process to do it so as to get > > good performance. > > > > Depending on how specialized your problem needs to be you might consider > > using one of the packages libMesh, MOOSE or deal.ii to manage the elements > > and element computations (they all use PETSc for the algebraic solvers) > > instead of doing it yourself; it is an involved process to do it all your > > self. > > > > Barry > > > > > > > > Thanks > > > > > > Yaxiong > > > > > > > > > From: Smith, Barry F. <bsm...@mcs.anl.gov> > > > Sent: Monday, February 4, 2019 5:21 PM > > > To: Yaxiong Chen > > > Cc: Mark Adams; PETSc users list > > > Subject: Re: [petsc-users] PETSC matrix assembling super slow > > > > > > > > > > > > > On Feb 4, 2019, at 3:17 PM, Yaxiong Chen via petsc-users > > > > <petsc-users@mcs.anl.gov> wrote: > > > > > > > > Hi Mark, > > > > Will the parameter MatMPIAIJSetPreallocation in influence the > > > > following part > > > > do i=mystart,nelem,nproc > > > > call ptSystem%getElementalMAT(i, Ae, auxRHSe, idx) > > > > ne=size(idx) > > > > idx=idx-1 !-1 since PETSC index starts from zero > > > > if (allocated(auxRHSe)) call > > > > VecSetValues(bvec,ne,idx,auxRHSe,ADD_VALUES,ierr) > > > > call MatSetValues(Amat,ne,idx,ne,idx,Ae,ADD_VALUES,ierr) > > > > end do > > > > I found this part will impede my assembling process. In my case ,the > > > > total DOF is 20800. I estimated the upper bound of number of nonzero > > > > entries in each row as 594. So I set f9 to be 20206 and f6 to be 10103 > > > > in the following command: > > > > call > > > > MatMPIAIJSetPreallocation(Amat,f9,PETSC_NULL_INTEGER,f6,PETSC_NULL_INTEGER, > > > > ierr) > > > > > > > > Running the code in sequential mode with -info I got the following > > > > information.And I can get the result even thought the assembling > > > > process is kind of slow(several times slower than using Mumps). > > > > [0] MatAssemblyBegin_MPIBAIJ(): Stash has 0 entries,uses 0 mallocs. > > > > [0] MatAssemblyBegin_MPIBAIJ(): Block-Stash has 0 entries, uses 0 > > > > mallocs. > > > > [0] MatAssemblyEnd_SeqBAIJ(): Matrix size: 20800 X 20800, block size 1; > > > > storage space: 13847 unneeded, 1030038 used > > > > [0] MatAssemblyEnd_SeqBAIJ(): Number of mallocs during MatSetValues is > > > > 62659 > > > > > > > > > Something is very wrong. The number of mallocs should be zero if you > > > have the correct preallocation. Are you calling MatZeroEntries() or some > > > other Mat routine before you call MatSetValues() ? > > > > > > > > > > [0] MatAssemblyEnd_SeqBAIJ(): Most nonzeros blocks in any row is 70 > > > > [0] MatCheckCompressedRow(): Found the ratio (num_zerorows > > > > 0)/(num_localrows 20800) < 0.6. Do not use CompressedRow routines. > > > > [0] PetscCommDuplicate(): Using internal PETSc communicator 4462889472 > > > > 140509341618528 > > > > [0] PetscCommDuplicate(): Using internal PETSc communicator 4462889472 > > > > 140509341618528 > > > > [0] PetscCommDuplicate(): Using internal PETSc communicator 4462889472 > > > > 140509341618528 > > > > [0] VecScatterCreate_Seq(): Special case: sequential copy > > > > [0] MatAssemblyEnd_SeqBAIJ(): Matrix size: 20800 X 0, block size 1; > > > > storage space: 104000 unneeded, 0 used > > > > [0] MatAssemblyEnd_SeqBAIJ(): Number of mallocs during MatSetValues is 0 > > > > [0] MatAssemblyEnd_SeqBAIJ(): Most nonzeros blocks in any row is 0 > > > > [0] MatCheckCompressedRow(): Found the ratio (num_zerorows > > > > 20800)/(num_localrows 20800) > 0.6. Use CompressedRow routines. > > > > aseembel time 282.54871800000001 > > > > [0] PetscCommDuplicate(): Using internal PETSc communicator 4462888960 > > > > 140509341442256 > > > > [0] PCSetUp(): Setting up PC for first time > > > > [0] PCSetUp(): Leaving PC with identical preconditioner since operator > > > > is unchanged > > > > [0] PCSetUp(): Leaving PC with identical preconditioner since operator > > > > is unchanged > > > > [0] PCSetUp(): Leaving PC with identical preconditioner since operator > > > > is unchanged > > > > [0] PCSetUp(): Leaving PC with identical preconditioner since operator > > > > is unchanged > > > > [0] PCSetUp(): Leaving PC with identical preconditioner since operator > > > > is unchanged > > > > [0] PCSetUp(): Leaving PC with identical preconditioner since operator > > > > is unchanged > > > > [0] PCSetUp(): Leaving PC with identical preconditioner since operator > > > > is unchanged > > > > > > > > However, when I use the parallel mode,I got the following information: > > > > [0] MatAssemblyBegin_MPIBAIJ(): Stash has 707965 entries,uses 6 mallocs. > > > > > > You have a lot of off-process MatSetValues(). That is one process is > > > generating a lot of matrix entries that belong on another process. This > > > is not desirable. Ideally each process will generate the matrix entries > > > that belong to that process so only a few matrix entries need to be > > > transported to another process. How are you partitioning the mesh and how > > > are you deciding which process computes which which entries in the > > > matrix? All of this may be need to be revisited. > > > > > > Barry > > > > > > > > > > > > > [0] MatAssemblyBegin_MPIBAIJ(): Block-Stash has 0 entries, uses 0 > > > > mallocs. > > > > > > > > it seems it never went to call > > > > MatAssemblyEnd(Amat,MAT_FINAL_ASSEMBLY,ierr) > > > > Is there anything I am doing wrong? > > > > Thanks > > > > > > > > Yaxiong Chen, > > > > Ph.D. Student > > > > > > > > School of Mechanical Engineering, 3171 > > > > 585 Purdue Mall > > > > West Lafayette, IN 47907 > > > > > > > > > > > > > > > > > > > > > > > > From: Mark Adams <mfad...@lbl.gov> > > > > Sent: Tuesday, January 29, 2019 10:02 PM > > > > To: Yaxiong Chen; PETSc users list > > > > Subject: Re: [petsc-users] PETSC matrix assembling super slow > > > > > > > > Optimized is a configuration flag not a versions. > > > > > > > > You need to figure out your number of non-zeros per row of you global > > > > matrix, or a bound on it, and supply that in MatMPIAIJSetPreallocation. > > > > Otherwise it has to allocate and copy memory often. > > > > > > > > You could increase your f9 on a serial run and see what runs best and > > > > then move to parallel with a value in f6 of about 1/2 of f9. > > > > > > > > On Tue, Jan 29, 2019 at 9:13 PM Yaxiong Chen <chen2...@purdue.edu> > > > > wrote: > > > > Thanks Mark, > > > > I use PETSC 3.9.4, is this the optimized version you called? > > > > Actually f9 and f6 are from the PETSC example. I don't know how to > > > > set the value correctly so I commend them. The size of my elemental > > > > matrix may vary. For 2D problem, the size of elemental matrix can be > > > > 24*24 or 32*32 or some other sizes. And the index is not continuous. In > > > > this case, the elemental matrix may interlace with each other in the > > > > global matrix, and I may have thousands of elemental matrix to be > > > > assembled. Does the preallocating suitable for this? > > > > > > > > Yaxiong Chen, > > > > Ph.D. Student > > > > > > > > School of Mechanical Engineering, 3171 > > > > 585 Purdue Mall > > > > West Lafayette, IN 47907 > > > > > > > > > > > > > > > > > > > > > > > > From: Mark Adams <mfad...@lbl.gov> > > > > Sent: Tuesday, January 29, 2019 8:25 PM > > > > To: Yaxiong Chen > > > > Cc: Song Gao; petsc-users@mcs.anl.gov > > > > Subject: Re: [petsc-users] PETSC matrix assembling super slow > > > > > > > > Slow assembly is often from not preallocating correctly. I am guessing > > > > that you are using Q1 element and f9==9, and thus the preallocation > > > > should be OK if this is a scalar problem on a regular grid and f6-==6 > > > > should be OK for the off processor allocation, if my assumptions are > > > > correct. > > > > > > > > You can run with -info, which will tell you how many allocation were > > > > done in assembly. Make sure that it is small (eg, 0). > > > > > > > > I see you use f90 array stuff 'idx-1'. Compilers can sometimes do crazy > > > > things with seeming simple code. You could just do this manually if you > > > > can find anything else. > > > > > > > > And I trust you are running an optimized version of PETSc. > > > > > > > > > > > > On Tue, Jan 29, 2019 at 6:22 PM Yaxiong Chen via petsc-users > > > > <petsc-users@mcs.anl.gov> wrote: > > > > Hi Song, > > > > I don't quite understand how I can use this command. I don't partition > > > > the gloabl matrix. If I add my elemental matrix to the global system it > > > > will be like this. And in my parallel part, I use each core to generate > > > > the elemental matrix in turn. In this case, I guess each core will be > > > > assigned the space for global matrix and finally be assembled.But > > > > according to the manual, it seems each core will store a part of the > > > > global matrix. Is the local submatrix in the > > > > MatMPIAIJSetPreallocation(Mat B,PetscInt d_nz,const PetscInt > > > > d_nnz[],PetscInt o_nz,const PetscInto_nnz[])the same as my elemental > > > > matrix? > > > > <pastedImage.png> > > > > > > > > > > > > Thanks > > > > > > > > Yaxiong Chen, > > > > Ph.D. Student > > > > > > > > School of Mechanical Engineering, 3171 > > > > 585 Purdue Mall > > > > West Lafayette, IN 47907 > > > > > > > > > > > > > > > > > > > > > > > > From: Song Gao <song.g...@mail.mcgill.ca> > > > > Sent: Tuesday, January 29, 2019 1:22 PM > > > > To: Yaxiong Chen > > > > Cc: Matthew Knepley; petsc-users@mcs.anl.gov > > > > Subject: Re: [petsc-users] PETSC matrix assembling super slow > > > > > > > > I think you would prefer to preallocate the matrix > > > > > > > > uncomment this line > > > > ! call > > > > MatMPIAIJSetPreallocation(Amat,f9,PETSC_NULL_INTEGER,f6,PETSC_NULL_INTEGER, > > > > ierr) > > > > > > > > > > > > > > > > Le mar. 29 janv. 2019, à 12 h 40, Yaxiong Chen via petsc-users > > > > <petsc-users@mcs.anl.gov> a écrit : > > > > Hello, > > > > > > > > I have a 2D system which is assembled by each elemental matrix. Ae is > > > > my elemental matrix, auxRHSe(:) and RHSe(:) and corresponding right > > > > hand side, idx is the global index. My code is as follow, however ,the > > > > assembling rate is super slow(Marked red in the code). I am not sure > > > > whether the assembling type is right or not. Since for each element, > > > > idx are not continuous numbers. Do you have any idea what is the better > > > > way to assemble the matrix? > > > > > > > > Thanks > > > > > > > > block > > > > PetscErrorCode ierr > > > > PetscMPIInt rank,nproc, mystart > > > > PetscInt nelem > > > > integer,allocatable ::info(:) > > > > real(wp), allocatable :: Ae(:,:), auxRHSe(:),RHSe(:) > > > > integer, allocatable :: idx(:) > > > > PetscScalar, pointer :: xx_v(:) > > > > > > > > PC prec > > > > PetscScalar :: val > > > > Vec xvec,bvec,uvec > > > > Mat Amat > > > > KSP ksp > > > > PetscViewer viewer > > > > PetscInt geq,j,k,ne,M,Istart,Iend > > > > PetscBool flg > > > > KSPConvergedReason reason > > > > Vec dummyVec, dummyVecs(1) > > > > MatNullSpace nullspace > > > > > > > > call PetscInitialize( PETSC_NULL_CHARACTER, ierr ) > > > > > > > > if (ierr .ne. 0) then > > > > print*,'Unable to initialize PETSc' > > > > stop > > > > endif > > > > call MPI_Comm_size(PETSC_COMM_WORLD,nproc,ierr) > > > > call MPI_Comm_rank(PETSC_COMM_WORLD,rank,ierr) > > > > mystart=rank+1 > > > > > > > > ! Parameter set > > > > info=ptsystem%getInitInfo() > > > > nelem = > > > > info(Info_EleMatNum)+info(Info_FixedDOFNum)+info(Info_NumConstrain) > > > > print*,'nelem',nelem > > > > !------------------------------------- > > > > ! Create Matrix > > > > call MatCreate(PETSC_COMM_WORLD,Amat,ierr) > > > > call MatSetSizes( Amat,PETSC_DECIDE, PETSC_DECIDE, info(1), > > > > info(1), ierr ) > > > > call MatSetType( Amat, MATMPIBAIJ, ierr ) > > > > ! call > > > > MatMPIAIJSetPreallocation(Amat,f9,PETSC_NULL_INTEGER,f6,PETSC_NULL_INTEGER, > > > > ierr) > > > > call MatSetFromOptions( Amat, ierr ) > > > > call MatSetUp( Amat, ierr ) > > > > call MatGetOwnershipRange( Amat, Istart, Iend, ierr ) > > > > > > > > xvec = tVec(0) > > > > call MatCreateVecs( Amat, PETSC_NULL_VEC, xvec, ierr ) > > > > call VecSetFromOptions( xvec, ierr ) > > > > call VecDuplicate( xvec, bvec, ierr ) > > > > call VecDuplicate( xvec, uvec, ierr ) > > > > > > > > t1 = MPI_WTime(); > > > > > > > > do i=mystart,nelem,nproc > > > > call ptSystem%getElementalMAT(i, Ae, auxRHSe, idx) > > > > ne=size(idx) > > > > if (allocated(auxRHSe)) call > > > > VecSetValues(bvec,ne,idx-1,auxRHSe,ADD_VALUES,ierr) > > > > call > > > > MatSetValues(Amat,ne,idx-1,ne,idx-1,Ae,ADD_VALUES,ierr) > > > > end do > > > > > > > > nelem = info(Info_EleRHSNum) > > > > mystart = rank+1 > > > > > > > > do i = mystart, nelem, nproc > > > > call ptSystem%getElementalRHS(i, RHSe, idx) > > > > print*,'idx',idx > > > > ne=size(idx) > > > > if (allocated(RHSe)) call > > > > VecSetValues(bvec,ne,idx-1,RHSe,ADD_VALUES,ierr) > > > > end do > > > > call MatAssemblyBegin(Amat,MAT_FINAL_ASSEMBLY,ierr) > > > > call MatAssemblyEnd(Amat,MAT_FINAL_ASSEMBLY,ierr) > > > > ! this part is slow, the for loop above is done but here it > > > > may get stuck > > > > call VecAssemblyBegin(bvec,ierr) > > > > ! For a 2500 DOF system, assembling > > > > only takes over 2 seconds > > > > call VecAssemblyEnd(bvec,ierr) > > > > ! But for a 10000 DOF system , it > > > > gets stuck > > > > t2 = MPI_WTime(); > > > > print*,'assembeling time',t2-t1 > > > > ! Solve > > > > call KSPCreate(PETSC_COMM_WORLD,ksp,ierr) > > > > ! Set operators. Here the matrix that defines the linear system > > > > ! also serves as the preconditioning matrix. > > > > call KSPSetOperators(ksp,Amat,Amat,ierr) > > > > call KSPSetFromOptions(ksp,ierr) > > > > ! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - > > > > - > > > > ! Solve the linear system > > > > ! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - > > > > - > > > > call KSPSetType(ksp,KSPCG,ierr) > > > > call KSPGetPC(ksp,prec,ierr) > > > > ! call KSPSetPCSide(ksp,PC_SYMMETRIC,ierr) > > > > call PCSetType(prec,PCJACOBI,ierr) > > > > call KSPSolve(ksp,bvec,xvec,ierr) > > > > call PetscFinalize(ierr) > > > > > > > > end block > > > > > > > > > > > > Yaxiong Chen, > > > > Ph.D. Student > > > > > > > > School of Mechanical Engineering, 3171 > > > > 585 Purdue Mall > > > > West Lafayette, IN 47907
