[petsc-users] Mysterious error code 77

[Quentin Chevalier]

Just a quick amend on the previous statement ; the problem arises in
sequential and parallel. The MWE as is is provided for the parallel
case, but imposing m_local=m makes it go sequential.

Cheers,

Quentin CHEVALIER – IA parcours recherche
LadHyX - Ecole polytechnique
__________



On Thu, 5 May 2022 at 10:34, Quentin Chevalier
<quentin.chevalier at polytechnique.edu> wrote:
>
> Hello all and thanks for your great work in bringing this very helpful package to the community !
>
> That said, I wouldn't need this mailing list if everything was running smoothly. I have a rather involved eigenvalue problem that I've been working on that's been throwing a mysterious error :
>>
>> petsc4py.PETSc.Error: error code 77
>>
>> [1] EPSSolve() at /usr/local/slepc/src/eps/interface/epssolve.c:149
>> [1] EPSSolve_KrylovSchur_Default() at /usr/local/slepc/src/eps/impls/krylov/krylovschur/krylovschur.c:289
>> [1] EPSGetStartVector() at /usr/local/slepc/src/eps/interface/epssolve.c:824
>> [1] Petsc has generated inconsistent data
>> [1] Initial vector is zero or belongs to the deflation space
>
>
> This problem occurs in parallel with two processors, using the petsc4py library using the dolfinx/dolfinx docker container. I have PETSc version 3.16.0, in complex mode, python 3, and I'm running all of that on a OpenSUSE Leap 15.2 machine (but I think the docker container has a Ubuntu OS).
>
> I wrote a minimal working example below, but I'm afraid the process for building the matrices is involved, so I decided to directly share the matrices instead : https://seminaris.polytechnique.fr/share/s/ryJ6L2nR4ketDwP
>
> They are in binary format, but inside the container I hope someone could reproduce my issue. A word on the structure and intent behind these matrices :
>
> QE is a diagonal rectangular real matrix. Think of it as some sort of preconditioner
> L is the least dense of them all, the only one that is complex, and in order to avoid inverting it I'm using two KSPs to compute solve problems on the fly
> Mf is a diagonal square real matrix, its on the right-hand side of the Generalised Hermitian Eigenvalue problem (I'm solving QE^H*L^-1H*L^-1*QE*x=lambda*Mf*x
>
> Full MWE is below :
>
> from petsc4py import PETSc as pet
> from slepc4py import SLEPc as slp
> from mpi4py.MPI import COMM_WORLD
>
> # Global sizes
> m_local=COMM_WORLD.rank*(490363-489780)+489780
> n_local=COMM_WORLD.rank*(452259-451743)+451743
> m=980143
> n=904002
>
> QE=pet.Mat().createAIJ([[m_local,m],[n_local,n]])
> L=pet.Mat().createAIJ([[m_local,m],[m_local,m]])
> Mf=pet.Mat().createAIJ([[n_local,n],[n_local,n]])
>
> viewerQE = pet.Viewer().createMPIIO("QE.dat", 'r', COMM_WORLD)
> QE.load(viewerQE)
> viewerL = pet.Viewer().createMPIIO("L.dat", 'r', COMM_WORLD)
> L.load(viewerL)
> viewerMf = pet.Viewer().createMPIIO("Mf.dat", 'r', COMM_WORLD)
> Mf.load(viewerMf)
>
> QE.assemble()
> L.assemble()
>
> KSPs = []
> # Useful solvers (here to put options for computing a smart R)
> for Mat in [L,L.hermitianTranspose()]:
> KSP = pet.KSP().create()
> KSP.setOperators(Mat)
> KSP.setFromOptions()
> KSPs.append(KSP)
> class LHS_class:
> def mult(self,A,x,y):
> w=pet.Vec().createMPI([m_local,m],comm=COMM_WORLD)
> z=pet.Vec().createMPI([m_local,m],comm=COMM_WORLD)
> QE.mult(x,w)
> KSPs[0].solve(w,z)
> KSPs[1].solve(z,w)
> QE.multTranspose(w,y)
>
> # Matrix free operator
> LHS=pet.Mat()
> LHS.create(comm=COMM_WORLD)
> LHS.setSizes([[n_local,n],[n_local,n]])
> LHS.setType(pet.Mat.Type.PYTHON)
> LHS.setPythonContext(LHS_class())
> LHS.setUp()
>
> # Eigensolver
> EPS = slp.EPS(); EPS.create()
> EPS.setOperators(LHS,Mf) # Solve QE^T*L^-1H*L^-1*QE*x=lambda*Mf*x
> EPS.setProblemType(slp.EPS.ProblemType.GHEP) # Specify that A is hermitian (by construction), and B is semi-positive
> EPS.setWhichEigenpairs(EPS.Which.LARGEST_MAGNITUDE) # Find largest eigenvalues
> EPS.setFromOptions()
> EPS.solve()
>
> Quentin CHEVALIER – IA parcours recherche
>
> LadHyX - Ecole polytechnique
>
> __________