Re: New changes for CG set type in 2.3.1-p7 ?

[Barry Smith <bsmith@mcs.anl.gov>]

   What about calling SetFromOptions after the call to KSPCGSetType()?

    Thanks
     Barry


On Thu, 23 Feb 2006, Satish Balay wrote:

> I just tried the following [with both c & fortran examples
> ksp/examples/tutorials/ex2.c, ex2f.F] And I get the expected behavior.
>
> Maybe KSPSetType() was not called before KSPCGSetType()?
>
> Satish
>
> --------
>
> > > >
>      call KSPCreate(PETSC_COMM_WORLD,ksp,ierr)
>      call KSPSetType(ksp,KSPCG,ierr)
>      call KSPCGSetType(ksp,KSP_CG_SYMMETRIC,ierr)
>      call KSPSetOperators(ksp,A,A,DIFFERENT_NONZERO_PATTERN,ierr)
> > > >
> asterix:/home/balay/spetsc/src/ksp/ksp/examples/tutorials>./ex2f -ksp_view
> KSP Object:
>  type: cg
>    CG or CGNE: variant SYMMETRIC
>  maximum iterations=10000, initial guess is zero
>  tolerances:  relative=1e-05, absolute=1e-50, divergence=10000
>  left preconditioning
> PC Object:
>  type: ilu
>    ILU: 0 levels of fill
>    ILU: max fill ratio allocated 1
>    ILU: tolerance for zero pivot 1e-12
>         out-of-place factorization
>         matrix ordering: natural
>         Factored matrix follows
>    Matrix Object:
>      type=aij, rows=9, cols=9
>      total: nonzeros=33, allocated nonzeros=45
>        not using I-node routines
>  linear system matrix = precond matrix:
>  Matrix Object:
>    type=aij, rows=9, cols=9
>    total: nonzeros=33, allocated nonzeros=45
>      not using I-node routines
> Norm of error 0.1215E-05 iterations     4
> asterix:/home/balay/spetsc/src/ksp/ksp/examples/tutorials>
>
>
> On Thu, 23 Feb 2006, Barry Smith wrote:
>
> >    Satish,
> >
> >     Can you please check this? We should be able to
> > call KSPCGSetType() either before or afterwards. It could
> > be that KSPSetFromOptions_CG() wrongly resets to the default
> > value. I looked at the code and didn't see any wrong logic.
> > Probably it may be easiest to just run in the debugger and
> > check if it wrongly reset.
> >
> >     Thanks
> >
> >     Barry
> >
> >
> > On Thu, 23 Feb 2006, abdul-rahman@tu-harburg.de wrote:
> >
> > > On Wed, 22 Feb 2006, Satish Balay wrote:
> > >
> > > I know where I did wrong now: the call below:
> > >
> > > > > > >       call KSPCGSetType( ksp, KSP_CG_SYMMETRIC, ierr )
> > > should have come _after_:
> > >
> > >  call KSPSetFromOptions(ksp,ierr)
> > >
> > > Otherwise it just goes with the default Hermitian even if I don't set the
> > > switch to Hermitian.
> > >
> > >
> > > > You should be able to verify if the correct type is used with
> > > > '-ksp_view' option.
> > > >
> > > > Satish
> > > Thank you again
> > >
> > >
> > > Razi