[petsc-dev] SLEPc failure

Tue Oct 31 10:17:16 CDT 2017

Thanks, this is helpful ! At least, I have some clues to dig deeper into.

The data set I have seems to be very sensitive: I knew B would likely be close to singular (even arpack, which seems to be the most stable, is not always robust enough depending on use cases and/or number of domains). To get things stable with arpack, I had to add "-mat_mumps_cntl_1 0.01 -mat_mumps_cntl_3 -0.0001 -mat_mumps_cntl_4 0.0001": so I let all that also when testing with krylovschur. I've just tried to suppress these extra options: I get the MUMPS error in numerical factorization. At least, it make sense...

Now, I added -eps_gen_non_hermitian and failed with EPS_DIVERGED_ITS. Increasing -eps_max_it does not help. So, I guess this is the end of the road.

Would you consider to expose (in future release) the tolerance of this check ? Or is this something you really want to keep private ? (whatever B is or not singular - I guess in my case, this would have not helped anyway)

Franck

----- Mail original -----
> De: "Jose E. Roman" <jroman at dsic.upv.es>
> À: "Franck Houssen" <franck.houssen at inria.fr>
> Cc: "For users of the development version of PETSc" <petsc-dev at mcs.anl.gov>
> Envoyé: Lundi 30 Octobre 2017 18:11:48
> Objet: Re: [petsc-dev] SLEPc failure
> 
> I am getting a MUMPS error in numerical factorization...
> Anyway, your B matrix is singular, with a high-dimensional nullspace. Maybe
> this is producing small negative values when computing v'*B*v.
> There is no way to relax the check. You should solve the problem as
> non-symmetric. Or use Arpack if it works for you.
> 
> Jose
> 
> 
> 
> > El 30 oct 2017, a las 17:16, Franck Houssen <franck.houssen at inria.fr>
> > escribió:
> > 
> > I deal with domain decomposition. It was faster/easier to generate files
> > with 1 proc: I guess the "dirichlet" and "neumann" matrices are the same
> > in this case, so one get the same files in the end... I didn't realized
> > that when I sent the files. My mistake.
> > 
> > At my side, when I use krylovschur, SLEPc fails using 1, 2, 4, 8, ... procs
> > (each proc performs a SLEPc solve that may fail or not - difficult to
> > catch one). For instance, I attached data of one failed domain out of 8 (8
> > MPI procs): matrices are very close but different. Moreover, I added EPS
> > logs of the same run and domain but replacing krylovschur with arpack when
> > SLEPc does not fail (regarding your remark that B could be indefinite, I
> > added -mat_mumps_icntl_33 1 to get the determinant).
> > 
> > Anyway, I don't expect you spend too much time on this. My understanding is
> > that there is no way to relax this check ? Correct ?
> > 
> > Franck
> > 
> > ----- Mail original -----
> >> De: "Jose E. Roman" <jroman at dsic.upv.es>
> >> À: "Franck Houssen" <franck.houssen at inria.fr>
> >> Cc: "For users of the development version of PETSc"
> >> <petsc-dev at mcs.anl.gov>
> >> Envoyé: Samedi 28 Octobre 2017 17:40:41
> >> Objet: Re: [petsc-dev] SLEPc failure
> >> 
> >> The two matrices are the same ...
> >> 
> >>> El 28 oct 2017, a las 13:11, Franck Houssen <franck.houssen at inria.fr>
> >>> escribió:
> >>> 
> >>> I just added that before EPSSetOperators:
> >>> PetscViewer viewerA;
> >>> PetscViewerBinaryOpen(PETSC_COMM_WORLD,"Atau.out",FILE_MODE_WRITE,&viewerA);
> >>> MatView(A,viewerA);
> >>> PetscViewer viewerB;
> >>> PetscViewerBinaryOpen(PETSC_COMM_WORLD,"Btau.out",FILE_MODE_WRITE,&viewerB);
> >>> MatView(B,viewerB);
> >>> 
> >>> At first, I avoided binary as I didn't know if the format handles
> >>> big/little endianness... So I prefered ASCII.
> >>> 
> >>> Binary data are attached.
> >>> 
> >>> Franck
> >>> 
> >>> PS : running debian with little endian.
> >>>>> python -c "import sys;print(0 if sys.byteorder=='big' else 1)"
> >>> 1
> >>> 
> >>> 
> >>> ----- Mail original -----
> >>>> De: "Jose E. Roman" <jroman at dsic.upv.es>
> >>>> À: "Franck Houssen" <franck.houssen at inria.fr>
> >>>> Cc: "For users of the development version of PETSc"
> >>>> <petsc-dev at mcs.anl.gov>
> >>>> Envoyé: Vendredi 27 Octobre 2017 18:52:56
> >>>> Objet: Re: [petsc-dev] SLEPc failure
> >>>> 
> >>>> I cannot load the files you sent. Please send the matrices in binary
> >>>> format.
> >>>> The easiest way is to run your program with -eps_view_mat0
> >>>> binary:Atau.bin
> >>>> -eps_view_mat1 binary:Btau.bin
> >>>> 
> >>>> However, the files are written at the end of EPSSolve() so if the solve
> >>>> fails
> >>>> then it will not create the files. You can try running with -eps_max_it
> >>>> 1
> >>>> or add code in your main program to write the matrices.
> >>>> 
> >>>> Jose
> >>>> 
> >>>> 
> >>>>> El 27 oct 2017, a las 12:28, Franck Houssen <franck.houssen at inria.fr>
> >>>>> escribió:
> >>>>> 
> >>>>> Maybe could be convenient for the users to have an option (or an
> >>>>> EPSSetXXX)
> >>>>> to relax that check ?
> >>>>> Data are attached.
> >>>>> 
> >>>>> Franck
> >>>>> 
> >>>>> ----- Mail original -----
> >>>>>> De: "Jose E. Roman" <jroman at dsic.upv.es>
> >>>>>> À: "Franck Houssen" <franck.houssen at inria.fr>
> >>>>>> Cc: "For users of the development version of PETSc"
> >>>>>> <petsc-dev at mcs.anl.gov>
> >>>>>> Envoyé: Vendredi 27 Octobre 2017 10:15:44
> >>>>>> Objet: Re: [petsc-dev] SLEPc failure
> >>>>>> 
> >>>>>> 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.houssen at 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" <jroman at dsic.upv.es>
> >>>>>>>> À: "Franck Houssen" <franck.houssen at inria.fr>
> >>>>>>>> Cc: "For users of the development version of PETSc"
> >>>>>>>> <petsc-dev at 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.houssen at 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
> >>>>>>>> 
> >>>>>>>> 
> >>>>>> 
> >>>>>> 
> >>>>> <ABtau.tar.gz>
> >>>> 
> >>>> 
> >>> <ABtau.tar.gz>
> >> 
> >> 
> > <slepc.tar.gz>
> 
> 