[petsc-users] PETSC for symmetric SLAE

Hello everyone! Can anyone help with the following question - if I am solving a symmetric SLAE (both structure and values), is it possible to store only the upper trinagular part of the matrix and apply all PETSC routines like KSPsolve etc.? I looked thorough the manual but it didn't find

Re: [petsc-users] PETSC for symmetric SLAE

Kirill Voronin kvoro...@labchem.sscc.ru writes: Hello everyone! Can anyone help with the following question - if I am solving a symmetric SLAE (both structure and values), is it possible to store only the upper trinagular part of the matrix and apply all PETSC routines like KSPsolve etc.?

Re: [petsc-users] Multiple solves with PCMG fail

Filippo Leonardi filippo.leona...@sam.math.ethz.ch writes: I'm stupid: somehow I was in master and didn't notice that. Sorry for the confusion. The branch 'mark/ksp-zero-eig' has been merged to 'master' now. signature.asc Description: PGP signature

Re: [petsc-users] Nullspaces for schur complement PCs

On 11 Nov 2014, at 04:28, Jed Brown j...@jedbrown.org wrote: Matthew Knepley knep...@gmail.com 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

Re: [petsc-users] Nullspaces for schur complement PCs

On Mon, Nov 10, 2014 at 10:28 PM, Jed Brown j...@jedbrown.org wrote: Matthew Knepley knep...@gmail.com 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

Re: [petsc-users] MatSolve in CG - PCPreSolve

Dear all, I think I further pinpointed the problem to the PCPreSolve. Both mine, as well as Petsc's PCG call PCPreSolve and enter the (pc-ops-presolve). But mine does not apply the presolve. Do I need to activate the PCPreSolve manually when I have written a KSP that I've registered using

Re: [petsc-users] MatSolve in CG - PCPreSolve

On Tue, Nov 11, 2014 at 6:27 AM, De Groof, Vincent Frans Maria vincent.de-gr...@uibk.ac.at wrote: Dear all, I think I further pinpointed the problem to the PCPreSolve. Both mine, as well as Petsc's PCG call PCPreSolve and enter the (pc-ops-presolve). But mine does not apply the

[petsc-users] schurcomplement of a rectangular system

Hi, in my works, I'm computing a formula (involving an L2 projection) of the form: (D - M^{-1} N) n where D,M and B are matrices and n is a vector. Operator (D - M^{-1} N) appears to be the Schur complement of the system ( M N ) ( ID ) and it is convenient for me to use a Mat of type

Re: [petsc-users] Lookup error in PetscTableFind()

Hi Barry, sorry for the late answer but I finally figured out what was causing all my issues. I have an integer declared as short somewhere in my code. That obviously is a poor decision that was made when the code was initially written. Given the size of my problem this lead to an integer

Re: [petsc-users] Nullspaces for schur complement PCs

Lawrence Mitchell lawrence.mitch...@imperial.ac.uk 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],

[petsc-users] passing solver options in fieldsplit

Hi, I am using Petsc to solver a multiphysics problem and I have the following issue. I partition my problem by declaring two fields: -ksp_type gmres -pc_type fieldsplit -pc_fieldsplit_type schur -pc_fieldsplit_schur_factorization_type full -pc_fieldsplit_schur_precondition selfp

[petsc-users] passing solver options in fieldsplit

Hi, I am using Petsc to solver a multiphysics problem and I have the following issue. I partition my problem by declaring two fields: -ksp_type gmres -pc_type fieldsplit -pc_fieldsplit_type schur -pc_fieldsplit_schur_factorization_type full -pc_fieldsplit_schur_precondition selfp

Re: [petsc-users] passing solver options in fieldsplit

Luc: Run your code with option '-help |grep mumps', then you'll see what prefix should be used in your case with the mumps option '-mat_mumps_icntl_14 30'. You may try even larger icntl_14. Hong Hi, I am using Petsc to solver a multiphysics problem and I have the following issue. I partition

[petsc-users] Origin of f2cblaslapack source code

Hello, A colleague of mine asked me about quad precision support in blas/lapack libraries. Naturally I said just use petsc... however he couldn't be convinced. I thought that the f2cblaslapack source which petsc's configure downloaded and compiled would be identical to that found at Netlib.

Re: [petsc-users] Origin of f2cblaslapack source code

The tool is /bin/maint/toclapack.sh and is applied to the Fortran BLAS/LAPACK source. Credits are at the top of the file. We don't run the script each time but run the script once and generate a tarball which is downloaded on request. The testing of the source code for quad precision