Alexander : Testing your matrix A.dat using petsc-3.3/src/ksp/ksp/examples/tutorials/ex10.c, I find that A is numerically singular:
a) petsc sequential lu: ./ex10 -f0 A.dat -ksp_type preonly -pc_type lu -rhs 0 [0]PETSC ERROR: Detected zero pivot in LU factorization: see http://www.mcs.anl.gov/petsc/documentation/faq.html#ZeroPivot! [0]PETSC ERROR: Zero pivot row 48 value 0 tolerance 2.22045e-14! b) mumps lu with np=8: mpiexec -n 8 ./ex10 -f0 A.dat -ksp_type preonly -pc_type lu -rhs 0 -pc_factor_mat_solver_package mumps ... [0]PETSC ERROR: Error in external library! [0]PETSC ERROR: Error reported by MUMPS in numerical factorization phase: INFO(1)=-1, INFO(2)=1 ... c) superlu_dist lu with np=8: mpiexec -n 8 ./ex10 -f0 A.dat -ksp_type preonly -pc_type lu -rhs 0 -pc_factor_mat_solver_package superlu_dist Number of iterations = 1 Residual norm 0.0103982 mumps cholesky with np=8: mpiexec -n 8 ./ex10 -f0 A.dat -ksp_type preonly -pc_type cholesky -rhs 0 -pc_factor_mat_solver_package mumps Number of iterations = 1 Residual norm 122744 With such large residual norms, the computed solution cannot be trusted :-( d) using -ksp_type gmres with pc=ilu: zero pivot pc=jacobi: iteration stagnates .. I'm convinced that matrix A is corrupted or obtained from an incorrect numerical model. Also note, your matrix A has size of approx. 60k, which is too large for sequential direct solver. The error on MatMatSolve() when calling ' -pc_type cholesky -pc_factor_mat_solver_package mumps' is a bug in our petsc-mumps interface. I've pushed a fix to petsc-3.3 http://petsc.cs.iit.edu/petsc/releases/petsc-3.3/rev/8badc49a596e Thanks for your report. Hong On 13.08.2012 19:01, Hong Zhang wrote: > >> Alexander : >> I need a simple code from you to reproduce the error for debugging. >> > > Hong, > > Attached you will find test.c that should reproduce this behavior with > petsc-3.3-p2. > Just run it with 1 and 2 procs as following: > ./mpirun -n 1 test -ksp_type preonly -pc_type cholesky > -pc_factor_mat_solver_package mumps -ksp_view > > Here is matrix I tested it on (15 MB): https://dl.dropbox.com/u/** > 60982984/A.dat <https://dl.dropbox.com/u/60982984/A.dat> > > > If mumps' solver is activated, then you should get error (sequential and >> parallel) >> [0]PETSC ERROR: No support for this operation for this object type! >> [0]PETSC ERROR: MatMatSolve_MUMPS() is not implemented yet! >> >> If petsc's direct solver is activated, then you should not be able to run >> it in parallel. >> > > Please note, that it works correctly for nproc > 1 since 1 year or so! > So I don't quite understand why there should be error thrown. > I just occasionally decided to test something in sequential version and > this thing happened. > > > >> Please check ~petsc/src/mat/examples/tests/**ex125.c >> to see if you used same calling procedure as this example. >> Note: I fixed a bug in this example and patched petsc-3.3. >> The update copy of ex125.c is attached for your convenience. >> >> Hong >> >> > > -- > Regards, > Alexander > > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20120821/9c8cab00/attachment.html>
