Re: [petsc-users] SLEPc: Convergence Problems

Thank You, That looks like what I need to do if the highly degenerate eigenpairs are my problem. I'll try that out this week and see if that helps. Chris On 10/13/16 20:01, Barry Smith wrote: > I would use MatGetSubMatrix() to pull out the part of the matrix you care > about and hand

Re: [petsc-users] SLEPc: Convergence Problems

See this description from Jed http://scicomp.stackexchange.com/questions/3298/appropriate-space-for-weak-solutions-to-an-elliptical-pde-with-mixed-inhomogeneo/3300#3300. In a simpler way you could just scale your diagonal entries which are 1 at the moment with a value that is out of your interest

Re: [petsc-users] large PetscCommDuplicate overhead

Mathew, Thanks for the additional information. This is all very weird since the same number of calls made to PetscCommDuplicate() are the same regardless of geometry and the time of the call shouldn't depend on the geometry. Would you be able to do another set of tests where you

Re: [petsc-users] Algorithms to remove null spaces in a singular system

Fande, What SNES method are you using? If you use SNESKSPONLY I think it is ok, it will solve for the norm minimizing least square solution during the one KSPSolve() and then return. Yes, if you use SNESNEWTONLS or others though the SNES solver will, as you say, think that progress

Re: [petsc-users] Algorithms to remove null spaces in a singular system

Fande, I have done some work, mostly understanding and documentation, on handling singular systems with KSP in the branch barry/improve-matnullspace-usage. This also includes a new example that solves both a symmetric example and an example where nullspace(A) != nullspace(A')

Re: [petsc-users] SLEPc: Convergence Problems

I would use MatGetSubMatrix() to pull out the part of the matrix you care about and hand that matrix off to SLEPc. Others prefer to remove the Dirichlet boundary value locations while doing the finite element assembly, this way those locations never appear in the matrix. The end

[petsc-users] SLEPc: Convergence Problems

Hello All, As there isn't a SLEPc specific list, it was recommended that I bring my question here. I am using SLEPc to solve a generalized eigenvalue problem generated as part of the Finite Element Method, but am having difficulty getting the diagonalizer to converge. I am worried that the

Re: [petsc-users] Slepc eigenvectors not orthonormalized

Forwarding to slepc-maint > On Oct 13, 2016, at 5:32 PM, Peetz, Darin T wrote: > > I've come across an irregularity when extracting the eigenvectors when using > the CISS method to solve the eigenvalue problem. I'm solving a generalized > hermitian problem, and it

[petsc-users] Slepc eigenvectors not orthonormalized

I've come across an irregularity when extracting the eigenvectors when using the CISS method to solve the eigenvalue problem. I'm solving a generalized hermitian problem, and it looks like the resulting eigenvectors are M-orthogonalized with each other (the M-inner products of different

Re: [petsc-users] Algorithms to remove null spaces in a singular system

One more question. Suppose that we are solving the singular linear system Ax = b. N(A) is the null space of A, and N(A^T) is the null space of the transpose of A. The linear system is solved using SNES, that is, F(x) = Ax-b = Ax -b_r - b_n. Here b_n in N(A^T), and b_r in R(A). During each

Re: [petsc-users] Algorithms to remove null spaces in a singular system

On Thu, Oct 13, 2016 at 9:06 AM, Kong, Fande wrote: > > > On Wed, Oct 12, 2016 at 10:21 PM, Jed Brown wrote: > >> Barry Smith writes: >> > I would make that a separate routine that the users would call first. >> >> We have VecMDot

Re: [petsc-users] Algorithms to remove null spaces in a singular system

"Kong, Fande" writes: > On Wed, Oct 12, 2016 at 10:21 PM, Jed Brown wrote: > >> Barry Smith writes: >> > I would make that a separate routine that the users would call first. >> >> We have VecMDot and VecMAXPY. I would propose

Re: [petsc-users] Algorithms to remove null spaces in a singular system

On Wed, Oct 12, 2016 at 10:21 PM, Jed Brown wrote: > Barry Smith writes: > > I would make that a separate routine that the users would call first. > > We have VecMDot and VecMAXPY. I would propose adding > > VecQR(PetscInt nvecs,Vec *vecs,PetscScalar

Re: [petsc-users] BVNormColumn

> El 13 oct 2016, a las 5:26, Bikash Kanungo escribió: > > Hi, > > I facing the following issue. I'm trying to use orthogonalize a set of > vectors (all complex) with a non-standard inner product (.i.e. with > BVSetMatrix). Let's call the basis vector to be BV and the