[petsc-users] superlu_dist produces random results

[Smith, Barry F.]

  Meaningless differences


> On Nov 15, 2017, at 2:26 PM, Kong, Fande <fande.kong at inl.gov> wrote:
> 
> 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,
> 
>