Hi Daniel, thank you very much for your answer!
I also tried a spectral transformation with the Arpack solver with the same result as without spectral transformation. I am interested in the smallest real eigenvalues. I know from previous calculations with the Krylov Schur solver form SLEPc that using or not using a spectral transformation makes a very big difference here. I am also solving the mechanical eigenproblem only: [M*eigenvalue+Kmm]*eigenvector=0 Here I am able to build a preconditioner out of the BlockSparseMatrix Kmm. The calculations with a preconditioner are really fast. My situation now is, that I use the same preconditioner for the mechanical-only system as for the coupled piezosystem (both build only out of Kmm). I think this should work as long as Kme*(Kee)^-1*Kem is relatively small with respect to Kmm but I will test this in further computations. I have also tried another approach using matrices instead of linear operators. This works better but I think using linear operators is the more stylish way (this is my first contact with linear operators and I want to learn to handle them). I do not want to use SLEPc here because I think handling the PETSc Matrices and vectors is too uncomfortable for my application. Am I right at this point? What do you think about using SLEPc here? Thank you very much in advance, I appreciate every help! Andreas Am Fr., 5. Juli 2019 um 20:15 Uhr schrieb Daniel Garcia-Sanchez < [email protected]>: > Hi Andreas, > > On Thursday, July 4, 2019 at 7:41:31 PM UTC+2, Andreas Hegendörfer wrote: >> >> Hello, >> >> 2. Are there better ways to solve this Eigenproblem, maybe with another >> solver? >> >> > Have you tried an spectral transformation? I'm not familiar with Arpack, I > use SLEPc. I think that you could use the > function ArpackSolver::set_shift(). sigma is your guess for the eigenvalue. > > Note that if you use an spectral transformation, you can not use an > iterative solver. You have to use a direct solver, but it considerably > accelerates the eigenvalue calculation. > > If your eigenvalue is from the interior of the spectrum and you don't do > an spectral transformation, it can take very long. > > Best, > Daniel > > -- > The deal.II project is located at http://www.dealii.org/ > For mailing list/forum options, see > https://groups.google.com/d/forum/dealii?hl=en > --- > You received this message because you are subscribed to the Google Groups > "deal.II User Group" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/dealii/a157c16e-4e0e-4b13-bd8d-ca3b2258fd30%40googlegroups.com > <https://groups.google.com/d/msgid/dealii/a157c16e-4e0e-4b13-bd8d-ca3b2258fd30%40googlegroups.com?utm_medium=email&utm_source=footer> > . > For more options, visit https://groups.google.com/d/optout. > -- The deal.II project is located at http://www.dealii.org/ For mailing list/forum options, see https://groups.google.com/d/forum/dealii?hl=en --- You received this message because you are subscribed to the Google Groups "deal.II User Group" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/dealii/CAF_nQ7CGGY5WRCD94zUcp7PmmKnHSWiHsL_Tv_68NmAV1TBqHQ%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
