Hi Kathrin, I'm not sure why lapack would fail here, you could try to look up that error "Error in Lapack xGGES 260" in the lapack documentation?
In my experience, lapack works robustly unless the problem is "too large": lapack treats the matrices as dense, so you "hit a wall" at some point and have to go to krylov subspace eigensolvers in slepc instead. But it doesn't sound like your meshes are too large here. It sounds like you're having issues for anything bigger than a 5x5 mesh, right? You could try to use one of slepc's krylov subspace eigensolvers (e.g. LANCZOS, ARNOLDI or KRYLOVSCHUR) to see if that works better? Also, you may already know this, but just in case: You can write libMesh matrices out using matrix->print_matlab(), and then read them into matlab --- you might find this helpful for comparing the matlab vs. slepc results for the larger meshes. David On 02/18/2014 02:32 PM, Kathrin Smetana wrote: > Hi all, > > I am trying to solve a generalized eigenvalue problem based on > eigenproblems_ex2.C, where the matrix A is singular (only a few entries > are different from zero) and the matrix B is symmetric and positive > definite and I am using lapack. I get convergence for a mesh of 30 > \times 5 \times 5 elements and I also used the Matlab function eigs and > got the same results, which seem reasonable. However, when I increase > the number of elements, I get the following error: > > > [0]PETSC ERROR: --------------------- Error Message > ------------------------------------ > [0]PETSC ERROR: Error in external library! > [0]PETSC ERROR: Error in Lapack xGGES 260! > [0]PETSC ERROR: > ------------------------------------------------------------------------ > [0]PETSC ERROR: Petsc Release Version 3.4.1, Jun, 10, 2013 > [0]PETSC ERROR: See docs/changes/index.html for recent updates. > [0]PETSC ERROR: See docs/faq.html for hints about trouble shooting. > [0]PETSC ERROR: See docs/index.html for manual pages. > [0]PETSC ERROR: > ------------------------------------------------------------------------ > [0]PETSC ERROR: ./example-opt on a arch-linux2-c-opt named > kathrin-Tempest-4200 by kathrin Tue Feb 18 11:29:10 2014 > [0]PETSC ERROR: Libraries linked from > /home/kathrin/Implementation/petsc-3.4.1/arch-linux2-c-opt/lib > [0]PETSC ERROR: Configure run at Wed Jul 31 19:43:19 2013 > [0]PETSC ERROR: Configure options > --with-mpi-dir=/home/kathrin/Implementation/mpich-install > --with-debugging=0 --with-shared-libraries=1 --with-dynamic-loading=1 > --download-parmetis=1 --download-mumps=1 --download-scalapack=1 > --download-blacs=1 --download-umfpack=1 --download-metis > --with-scalar-type=complex --with-clanguage=cxx > PETSC_DIR=/home/kathrin/Implementation/petsc-3.4.1 > [0]PETSC ERROR: > ------------------------------------------------------------------------ > [0]PETSC ERROR: DSSolve_GNHEP() line 581 in > /home/kathrin/Implementation/slepc-3.4.0/src/ds/impls/gnhep/dsgnhep.c > [0]PETSC ERROR: DSSolve() line 421 in > /home/kathrin/Implementation/slepc-3.4.0/src/ds/interface/dsops.c > [0]PETSC ERROR: EPSSolve_LAPACK() line 143 in > /home/kathrin/Implementation/slepc-3.4.0/src/eps/impls/lapack/lapack.c > [0]PETSC ERROR: EPSSolve() line 116 in > /home/kathrin/Implementation/slepc-3.4.0/src/eps/interface/solve.c > [0]PETSC ERROR: _solve_generalized_helper() line 498 in > "unknowndirectory/"src/solvers/slepc_eigen_solver.C > application called MPI_Abort(MPI_COMM_WORLD, 76) - process 0 > > > Does anyone have any recommendations/ideas? > > Thanks, > Kathrin > > > > ------------------------------------------------------------------------------ > Managing the Performance of Cloud-Based Applications > Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. > Read the Whitepaper. > http://pubads.g.doubleclick.net/gampad/clk?id=121054471&iu=/4140/ostg.clktrk > _______________________________________________ > Libmesh-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/libmesh-users ------------------------------------------------------------------------------ Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471&iu=/4140/ostg.clktrk _______________________________________________ Libmesh-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/libmesh-users
