Using SLEPc PEPLinear

[Claire Lestringant]

Hi,

I'm new using SLEPc via slepc4py interface (so maybe I am missing something, thank you in advance for your corrections). I try to solve a quadratic eigenvalue problem with PEP solver 'linear' (explicit linearization) via following code :

E = SLEPc.PEP().create()
E.setOperators([K,G,M])
E.setType('linear')
E.setProblemType(2)
E.solve()

And I get the following error :

File "PEP.pyx", line 540, in slepc4py.SLEPc.PEP.solve (src/slepc4py.SLEPc.c:34248)
petsc4py.PETSc.Error: error code 1
[0] PEPSolve() line 82 in .../slepc-3.5/src/pep/interface/pepsolve.c
[0] PEPSetUp() line 105 in .../slepc-3.5/src/pep/interface/pepsetup.c
[0] PEPSetUp_Linear() line 152 in .../slepc-3.5/src/pep/impls/linear/linear.c
[0] EPSSetUp() line 120 in .../slepc-3.5/src/eps/interface/epssetup.c
[0] EPSSetUp_KrylovSchur() line 95 in .../slepc-     3.5/src/eps/impls/krylov/krylovschur/krylovschur.c
[0] Wrong value of eps->which

Maybe I am missing some settings, but I can't find the related methods in slepc4py package (like PEPLinearsetCompanionForm, PEPLinearsetEPS or PEPLinearsetExplicitMatrix described in SLEPc documentation...)

Thank you in advance,

[Jose E. Roman]

Do you get the same if you add E.setFromOptions() before E.solve() as in example demo/ex5.py?

[Claire Lestringant]

I get the same error message with :

E = SLEPc.PEP().create()
E.setOperators([K,G,M])
E.setType('linear')
E.setProblemType(2)
E.setFromOptions()
E.solve()

... ex5.py uses default 'TOAR' method, right ?

[Jose E. Roman]

Yes. Does TOAR work for you? If so, do not bother about LINEAR because you won't get any additional benefit.

[Claire Lestringant]

Yes it works. Ok, since my problem is hermitian, I though I could improve resolution using explicit linearization (TOAR method seems very general).

[Jose E. Roman]

I have pushed a fix for this in slepc-master. Thanks for reporting.

[Claire Lestringant]

Ok, how can I get an update for this ? Thanks

[Jose E. Roman]

You are using the repository version of SLEPc, right? Have to git pull at $SLEPC_DIR then rebuild SLEPc, then rerun setup.py in slepc4py.