I'm a newbie with both PETSc & SLEPc and have had some trouble finding examples/tutorials for newbies. I've looked through the examples in the PETSc and SLEPc directories but still am having "issues" seeing how to set this up for the type of problem I have.
SLEPc ex7.c is a good place to start but there's still how best to store the matrices and which EPS to use (besides LAPACK). Found a PDF, "MATRICES IN PETSc", (after much googling) but not sure which of the many forms will work and which is best. ---John On Mon, Aug 1, 2011 at 2:12 PM, John Chludzinski <jchludzinski at gmail.com>wrote: > I have 2 files (matrices) in simply binary form (IEEE-754, generated by > some C code) and wished to get them into canonical "PETSc binary form". So I > did: > > Mat A; > PetscScalar *a; > > ierr = PetscMalloc(SIZE*SIZE*sizeof(PetscScalar),&a);CHKERRQ(ierr); > // stored the file into the space malloc'ed for 'a'. > MatCreateSeqDense(PETSC_COMM_SELF, n, n, a, &A); > MatView(A,PETSC_VIEWER_BINARY_(PETSC_COMM_WORLD)); > > This works when I use: -eps_type lapack. As long as I store the matrix in > column major order. > > ---John > > On Mon, Aug 1, 2011 at 1:40 PM, Matthew Knepley <knepley at gmail.com> wrote: > > On Mon, Aug 1, 2011 at 5:27 PM, John Chludzinski <jchludzinski at > gmail.com>wrote: >> >>> I create 2 matrices using: >>> >>> MatCreateSeqDense(PETSC_COMM_SELF, n, n, Ka, &A); >>> MatCreateSeqDense(PETSC_COMM_SELF, n, n, Kb, &B); >>> >>> These matrices are 99% zeros ( 16,016,004 entries and 18660 non-zeros). >>> They are symmetric and real. Their tri-diagonal elements are non-zero plus >>> a few other entries. >>> >> >> Please give some justification for doing this? On the surface, it just >> seems perverse. >> >> Matt >> >> >>> I tried to use ex7 for the generalized eigenvalue problem: >>> >>> ./ex7.exe -f1 k.dat -f2 m.dat -eps_gen_hermitian -eps_smallest_real > >>> x.out 2>&1 >>> >>> without specifying an EPS and get: >>> >>> Generalized eigenproblem stored in file. >>> >>> Reading REAL matrices from binary files... >>> Number of iterations of the method: 500 >>> Number of linear iterations of the method: 4009 >>> Solution method: krylovschur >>> >>> Number of requested eigenvalues: 1 >>> Stopping condition: tol=1e-07, maxit=500 >>> Number of converged approximate eigenpairs: 0 >>> >>> Is krylovschur inappropriate for this problem or have I set up the >>> problem incorrectly by using MatCreateSeqDense(...) to create the matrix >>> input files in PETSc binary form? >>> >>> ---John >>> >> >> >> -- >> What most experimenters take for granted before they begin their >> experiments is infinitely more interesting than any results to which their >> experiments lead. >> -- Norbert Wiener >> > > > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20110801/faeca1be/attachment.htm>
