There is no new option. What I mean is that from 3.7 to 3.8 we changed the line that produces this error. But it seems that it is still failing in your problem. Maybe your B matrix is indefinite or not exactly symmetric. Can you send me the matrices? Jose
> El 27 oct 2017, a las 9:57, Franck Houssen <franck.hous...@inria.fr> escribió: > > I use the development version (bitbucket clone). How to relax the check ? At > command line option ? > > Franck > > ----- Mail original ----- >> De: "Jose E. Roman" <jro...@dsic.upv.es> >> À: "Franck Houssen" <franck.hous...@inria.fr> >> Cc: "For users of the development version of PETSc" <petsc-dev@mcs.anl.gov> >> Envoyé: Jeudi 26 Octobre 2017 18:49:22 >> Objet: Re: [petsc-dev] SLEPc failure >> >> >>> El 26 oct 2017, a las 18:36, Franck Houssen <franck.hous...@inria.fr> >>> escribió: >>> >>> Here is a stack I end up with when trying to solve an eigen problem (real, >>> sym, generalized) with SLEPc. My understanding is that, during the Gram >>> Schmidt orthogonalisation, the projection of one basis vector turns out to >>> be null. >>> First, is this correct ? Second, in such cases, are there some recommended >>> "recipe" to test/try (options) to get a clue on the problem ? (I would >>> unfortunately perfectly understand the answer could be no !... As this >>> totally depends on A/B). >>> >>> With arpack, the eigen problem is solved (so the matrix A and B I use seems >>> to be relevant). But, when I change from arpack to >>> krylovschur/ciss/arnoldi, I get the stack below. >>> >>> Franck >>> >>> [0]PETSC ERROR: #1 BV_SafeSqrt() >>> [0]PETSC ERROR: #2 BVNorm_Private() >>> [0]PETSC ERROR: #3 BVNormColumn() >>> [0]PETSC ERROR: #4 BV_NormVecOrColumn() >>> [0]PETSC ERROR: #5 BVOrthogonalizeCGS1() >>> [0]PETSC ERROR: #6 BVOrthogonalizeGS() >>> [0]PETSC ERROR: #7 BVOrthonormalizeColumn() >>> [0]PETSC ERROR: #8 EPSFullLanczos() >>> [0]PETSC ERROR: #9 EPSSolve_KrylovSchur_Symm() >>> [0]PETSC ERROR: #10 EPSSolve() >> >> Is this with SLEPc 3.8? In SLEPc 3.8 we relaxed this check so I would suggest >> trying with it. >> Jose >> >>