[petsc-users] CG with right preconditioning supports NONE norm type only

[Barry Smith]

   A proposed fix https://bitbucket.org/petsc/petsc/pull-requests/645/do-not-assume-that-all-ksp-methods-support

   Needs Jed's approval.

   Barry


  
> On Mar 8, 2017, at 10:33 AM, Barry Smith <bsmith at mcs.anl.gov> wrote:
> 
> 
>  Please tell us how you got this output. 
> 
>  PETSc CG doesn't even implement right preconditioning. If you ask for it it should error out. CG supports no norm computation with left preconditioning.
> 
>   Barry
> 
>> On Mar 8, 2017, at 10:26 AM, Kong, Fande <fande.kong at inl.gov> wrote:
>> 
>> Hi All,
>> 
>> The NONE norm type is supported only when CG is used with a right preconditioner. Any reason for this?
>> 
>> 
>> 
>> 0 Nonlinear |R| = 1.732051e+00
>>      0 Linear |R| = 0.000000e+00
>>      1 Linear |R| = 0.000000e+00
>>      2 Linear |R| = 0.000000e+00
>>      3 Linear |R| = 0.000000e+00
>>      4 Linear |R| = 0.000000e+00
>>      5 Linear |R| = 0.000000e+00
>>      6 Linear |R| = 0.000000e+00
>> 1 Nonlinear |R| = 1.769225e-08
>>      0 Linear |R| = 0.000000e+00
>>      1 Linear |R| = 0.000000e+00
>>      2 Linear |R| = 0.000000e+00
>>      3 Linear |R| = 0.000000e+00
>>      4 Linear |R| = 0.000000e+00
>>      5 Linear |R| = 0.000000e+00
>>      6 Linear |R| = 0.000000e+00
>>      7 Linear |R| = 0.000000e+00
>>      8 Linear |R| = 0.000000e+00
>>      9 Linear |R| = 0.000000e+00
>>     10 Linear |R| = 0.000000e+00
>> 2 Nonlinear |R| = 0.000000e+00
>> SNES Object: 1 MPI processes
>>  type: newtonls
>>  maximum iterations=50, maximum function evaluations=10000
>>  tolerances: relative=1e-08, absolute=1e-50, solution=1e-50
>>  total number of linear solver iterations=18
>>  total number of function evaluations=23
>>  norm schedule ALWAYS
>>  SNESLineSearch Object:   1 MPI processes
>>    type: bt
>>      interpolation: cubic
>>      alpha=1.000000e-04
>>    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:   1 MPI processes
>>    type: cg
>>    maximum iterations=10000, initial guess is zero
>>    tolerances:  relative=1e-05, absolute=1e-50, divergence=10000.
>>    right preconditioning
>>    using NONE norm type for convergence test
>>  PC Object:   1 MPI processes
>>    type: hypre
>>      HYPRE BoomerAMG preconditioning
>>      HYPRE BoomerAMG: Cycle type V
>>      HYPRE BoomerAMG: Maximum number of levels 25
>>      HYPRE BoomerAMG: Maximum number of iterations PER hypre call 1
>>      HYPRE BoomerAMG: Convergence tolerance PER hypre call 0.
>>      HYPRE BoomerAMG: Threshold for strong coupling 0.25
>>      HYPRE BoomerAMG: Interpolation truncation factor 0.
>>      HYPRE BoomerAMG: Interpolation: max elements per row 0
>>      HYPRE BoomerAMG: Number of levels of aggressive coarsening 0
>>      HYPRE BoomerAMG: Number of paths for aggressive coarsening 1
>>      HYPRE BoomerAMG: Maximum row sums 0.9
>>      HYPRE BoomerAMG: Sweeps down         1
>>      HYPRE BoomerAMG: Sweeps up           1
>>      HYPRE BoomerAMG: Sweeps on coarse    1
>>      HYPRE BoomerAMG: Relax down          symmetric-SOR/Jacobi
>>      HYPRE BoomerAMG: Relax up            symmetric-SOR/Jacobi
>>      HYPRE BoomerAMG: Relax on coarse     Gaussian-elimination
>>      HYPRE BoomerAMG: Relax weight  (all)      1.
>>      HYPRE BoomerAMG: Outer relax weight (all) 1.
>>      HYPRE BoomerAMG: Using CF-relaxation
>>      HYPRE BoomerAMG: Not using more complex smoothers.
>>      HYPRE BoomerAMG: Measure type        local
>>      HYPRE BoomerAMG: Coarsen type        Falgout
>>      HYPRE BoomerAMG: Interpolation type  classical
>>    linear system matrix followed by preconditioner matrix:
>>    Mat Object:     1 MPI processes
>>      type: mffd
>>      rows=9, cols=9
>>        Matrix-free approximation:
>>          err=1.49012e-08 (relative error in function evaluation)
>>          Using wp compute h routine
>>              Does not compute normU
>>    Mat Object:    ()     1 MPI processes
>>      type: seqaij
>>      rows=9, cols=9
>>      total: nonzeros=49, allocated nonzeros=49
>>      total number of mallocs used during MatSetValues calls =0
>>        not using I-node routines
>> 
>> Fande,
>> 
>