[petsc-users] Problem setting Fieldsplit fields

[Nicolas Barnafi]

> There are a number of common errors:
> 
>    1) Your PC has a prefix
> 
>    2) You have not called KSPSetFromOptions() here
> 
> Can you send the -ksp_view output?

The PC at least has no prefix. I had to set ksp_rtol to 1 to get through 
the solution process, you will find both the petsc_rc and the ksp_view 
at the bottom of this message.

Options are indeed being set from the options file, but there must be 
something missing at a certain level. Thanks for looking into this.

Best

---- petsc_rc file

-ksp_monitor
-ksp_type gmres
-ksp_view
-mat_type aij
-ksp_norm_type unpreconditioned
-ksp_atol 1e-14
-ksp_rtol 1
-pc_type fieldsplit
-pc_fieldsplit_type multiplicative

---- ksp_view

KSP Object: 1 MPI process
   type: gmres
     restart=500, using Classical (unmodified) Gram-Schmidt 
Orthogonalization with no iterative refinement
     happy breakdown tolerance 1e-30
   maximum iterations=10000, nonzero initial guess
   tolerances:  relative=1., absolute=1e-14, divergence=10000.
   right preconditioning
   using UNPRECONDITIONED norm type for convergence test
PC Object: 1 MPI process
   type: fieldsplit
     FieldSplit with MULTIPLICATIVE composition: total splits = 4
     Solver info for each split is in the following KSP objects:
   Split number 0 Defined by IS
   KSP Object: (fieldsplit_0_) 1 MPI process
     type: preonly
     maximum iterations=10000, initial guess is zero
     tolerances:  relative=1e-05, absolute=1e-50, divergence=10000.
     left preconditioning
     using DEFAULT norm type for convergence test
   PC Object: (fieldsplit_0_) 1 MPI process
     type: ilu
     PC has not been set up so information may be incomplete
       out-of-place factorization
       0 levels of fill
       tolerance for zero pivot 2.22045e-14
       matrix ordering: natural
       matrix solver type: petsc
       matrix not yet factored; no additional information available
     linear system matrix = precond matrix:
     Mat Object: (fieldsplit_0_) 1 MPI process
       type: seqaij
       rows=615, cols=615
       total: nonzeros=9213, allocated nonzeros=9213
       total number of mallocs used during MatSetValues calls=0
         not using I-node routines
   Split number 1 Defined by IS
   KSP Object: (fieldsplit_1_) 1 MPI process
     type: preonly
     maximum iterations=10000, initial guess is zero
     tolerances:  relative=1e-05, absolute=1e-50, divergence=10000.
     left preconditioning
     using DEFAULT norm type for convergence test
   PC Object: (fieldsplit_1_) 1 MPI process
     type: ilu
     PC has not been set up so information may be incomplete
       out-of-place factorization
       0 levels of fill
       tolerance for zero pivot 2.22045e-14
       matrix ordering: natural
       matrix solver type: petsc
       matrix not yet factored; no additional information available
     linear system matrix = precond matrix:
     Mat Object: (fieldsplit_1_) 1 MPI process
       type: seqaij
       rows=64, cols=64
       total: nonzeros=0, allocated nonzeros=0
       total number of mallocs used during MatSetValues calls=0
         using I-node routines: found 13 nodes, limit used is 5
   Split number 2 Defined by IS
   KSP Object: (fieldsplit_2_) 1 MPI process
     type: preonly
     maximum iterations=10000, initial guess is zero
     tolerances:  relative=1e-05, absolute=1e-50, divergence=10000.
     left preconditioning
     using DEFAULT norm type for convergence test
   PC Object: (fieldsplit_2_) 1 MPI process
     type: ilu
     PC has not been set up so information may be incomplete
       out-of-place factorization
       0 levels of fill
       tolerance for zero pivot 2.22045e-14
       matrix ordering: natural
       matrix solver type: petsc
       matrix not yet factored; no additional information available
     linear system matrix = precond matrix:
     Mat Object: (fieldsplit_2_) 1 MPI process
       type: seqaij
       rows=240, cols=240
       total: nonzeros=2140, allocated nonzeros=2140
       total number of mallocs used during MatSetValues calls=0
         not using I-node routines
   Split number 3 Defined by IS
   KSP Object: (fieldsplit_3_) 1 MPI process
     type: preonly
     maximum iterations=10000, initial guess is zero
     tolerances:  relative=1e-05, absolute=1e-50, divergence=10000.
     left preconditioning
     using DEFAULT norm type for convergence test
   PC Object: (fieldsplit_3_) 1 MPI process
     type: ilu
     PC has not been set up so information may be incomplete
       out-of-place factorization
       0 levels of fill
       tolerance for zero pivot 2.22045e-14
       matrix ordering: natural
       matrix solver type: petsc
       matrix not yet factored; no additional information available
     linear system matrix = precond matrix:
     Mat Object: (fieldsplit_3_) 1 MPI process
       type: seqaij
       rows=300, cols=300
       total: nonzeros=2292, allocated nonzeros=2292
       total number of mallocs used during MatSetValues calls=0
         not using I-node routines
   linear system matrix = precond matrix:
   Mat Object: 1 MPI process
     type: seqaij
     rows=1219, cols=1219
     total: nonzeros=26443, allocated nonzeros=26443
     total number of mallocs used during MatSetValues calls=0
       not using I-node routines
	      solving time: 0.00449609
	        iterations: 0
	   estimated error: 25.4142