[petsc-users] superlu_dist produces random results

[Kong, Fande]

Hi,

There is a heat conduction problem. When superlu_dist is used as a
preconditioner, we have random results from different runs. Is there a
random algorithm in superlu_dist? If we use ASM or MUMPS as the
preconditioner, we then don't have this issue.

run 1:

 0 Nonlinear |R| = 9.447423e+03
      0 Linear |R| = 9.447423e+03
      1 Linear |R| = 1.013384e-02
      2 Linear |R| = 4.020995e-08
 1 Nonlinear |R| = 1.404678e-02
      0 Linear |R| = 1.404678e-02
      1 Linear |R| = 5.104757e-08
      2 Linear |R| = 7.699637e-14
 2 Nonlinear |R| = 5.106418e-08


run 2:

 0 Nonlinear |R| = 9.447423e+03
      0 Linear |R| = 9.447423e+03
      1 Linear |R| = 1.013384e-02
      2 Linear |R| = 4.020995e-08
 1 Nonlinear |R| = 1.404678e-02
      0 Linear |R| = 1.404678e-02
      1 Linear |R| = 5.109913e-08
      2 Linear |R| = 7.189091e-14
 2 Nonlinear |R| = 5.111591e-08

run 3:

 0 Nonlinear |R| = 9.447423e+03
      0 Linear |R| = 9.447423e+03
      1 Linear |R| = 1.013384e-02
      2 Linear |R| = 4.020995e-08
 1 Nonlinear |R| = 1.404678e-02
      0 Linear |R| = 1.404678e-02
      1 Linear |R| = 5.104942e-08
      2 Linear |R| = 7.465572e-14
 2 Nonlinear |R| = 5.106642e-08

run 4:

 0 Nonlinear |R| = 9.447423e+03
      0 Linear |R| = 9.447423e+03
      1 Linear |R| = 1.013384e-02
      2 Linear |R| = 4.020995e-08
 1 Nonlinear |R| = 1.404678e-02
      0 Linear |R| = 1.404678e-02
      1 Linear |R| = 5.102730e-08
      2 Linear |R| = 7.132220e-14
 2 Nonlinear |R| = 5.104442e-08

Solver details:

SNES Object: 8 MPI processes
  type: newtonls
  maximum iterations=15, maximum function evaluations=10000
  tolerances: relative=1e-08, absolute=1e-11, solution=1e-50
  total number of linear solver iterations=4
  total number of function evaluations=7
  norm schedule ALWAYS
  SNESLineSearch Object: 8 MPI processes
    type: basic
    maxstep=1.000000e+08, minlambda=1.000000e-12
    tolerances: relative=1.000000e-08, absolute=1.000000e-15,
lambda=1.000000e-08
    maximum iterations=40
  KSP Object: 8 MPI processes
    type: gmres
      restart=30, using Classical (unmodified) Gram-Schmidt
Orthogonalization with no iterative refinement
      happy breakdown tolerance 1e-30
    maximum iterations=100, initial guess is zero
    tolerances:  relative=1e-06, absolute=1e-50, divergence=10000.
    right preconditioning
    using UNPRECONDITIONED norm type for convergence test
  PC Object: 8 MPI processes
    type: lu
      out-of-place factorization
      tolerance for zero pivot 2.22045e-14
      matrix ordering: natural
      factor fill ratio given 0., needed 0.
        Factored matrix follows:
          Mat Object: 8 MPI processes
            type: superlu_dist
            rows=7925, cols=7925
            package used to perform factorization: superlu_dist
            total: nonzeros=0, allocated nonzeros=0
            total number of mallocs used during MatSetValues calls =0
              SuperLU_DIST run parameters:
                Process grid nprow 4 x npcol 2
                Equilibrate matrix TRUE
                Matrix input mode 1
                Replace tiny pivots FALSE
                Use iterative refinement TRUE
                Processors in row 4 col partition 2
                Row permutation LargeDiag
                Column permutation METIS_AT_PLUS_A
                Parallel symbolic factorization FALSE
                Repeated factorization SamePattern
    linear system matrix followed by preconditioner matrix:
    Mat Object: 8 MPI processes
      type: mffd
      rows=7925, cols=7925
        Matrix-free approximation:
          err=1.49012e-08 (relative error in function evaluation)
          Using wp compute h routine
              Does not compute normU
    Mat Object: () 8 MPI processes
      type: mpiaij
      rows=7925, cols=7925
      total: nonzeros=63587, allocated nonzeros=63865
      total number of mallocs used during MatSetValues calls =0
        not using I-node (on process 0) routines


Fande,
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