[petsc-users] Select a preconditioner for SLEPc eigenvalue solver Jacobi-Davidson

[Fande Kong]

Hi All,

It looks like the preconditioner is hard-coded in the Jacobi-Davidson
solver. I could not select a preconditioner rather than the default setting.

For example, I was trying to select LU, but PC NONE was still used.  I ran
standard example 2 in slepc/src/eps/examples/tutorials, and had the
following results.


Thanks,

Fande


./ex2 -eps_type jd -st_ksp_type gmres  -st_pc_type lu   -eps_view

2-D Laplacian Eigenproblem, N=100 (10x10 grid)

EPS Object: 1 MPI processes
  type: jd
    search subspace is orthogonalized
    block size=1
    type of the initial subspace: non-Krylov
    size of the subspace after restarting: 6
    number of vectors after restarting from the previous iteration: 1
    threshold for changing the target in the correction equation (fix): 0.01
  problem type: symmetric eigenvalue problem
  selected portion of the spectrum: largest eigenvalues in magnitude
  number of eigenvalues (nev): 1
  number of column vectors (ncv): 17
  maximum dimension of projected problem (mpd): 17
  maximum number of iterations: 1700
  tolerance: 1e-08
  convergence test: relative to the eigenvalue
BV Object: 1 MPI processes
  type: svec
  17 columns of global length 100
  vector orthogonalization method: classical Gram-Schmidt
  orthogonalization refinement: if needed (eta: 0.7071)
  block orthogonalization method: GS
  doing matmult as a single matrix-matrix product
DS Object: 1 MPI processes
  type: hep
  solving the problem with: Implicit QR method (_steqr)
ST Object: 1 MPI processes
  type: precond
  shift: 1.79769e+308
  number of matrices: 1
  KSP Object: (st_) 1 MPI processes
    type: gmres
      restart=30, using Classical (unmodified) Gram-Schmidt
Orthogonalization with no iterative refinement
      happy breakdown tolerance 1e-30
    maximum iterations=90, initial guess is zero
    tolerances:  relative=0.0001, absolute=1e-50, divergence=10000.
    left preconditioning
    using PRECONDITIONED norm type for convergence test
  PC Object: (st_) 1 MPI processes
    type: none
    linear system matrix = precond matrix:
    Mat Object: 1 MPI processes
      type: shell
      rows=100, cols=100
 Solution method: jd

 Number of requested eigenvalues: 1
 Linear eigensolve converged (1 eigenpair) due to CONVERGED_TOL; iterations
20
 ---------------------- --------------------
            k             ||Ax-kx||/||kx||
 ---------------------- --------------------
        7.837972            7.71944e-10
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