[petsc-users] About the "PetscOptionsSetValue" usage

[Filippo Spiga]

I was referring to the input file of my application, I do not want to pass
PETSc option by the command line or using another specific file input.

Anyway, I tried the strategy "KSPSetOptionsPrefix(..)"/"SNES
SetOptionsPrefix(...);" + "PetscOptionsSetValue(...)" and it works very
well!!! But now I have another question. Using these routines, every time
I cyclically call KSP and/or SNES in my program I put new options inside the
PETSc option database. Most of these options, that have the same prefix, are
replicated.  Is this a problem? Is it always true that I will use the last
one inserted?


Let's consider this example:

begin program
  begin program iteration number 1
     CreateKSP(myksp1);
     PetscOptionsSetValue("-a", "1");
     PetscOptionsSetValue("-b", "2");
     KSPSolve(myksp1)
     DestroyKSP(myksp1);
  end program iteration number 1

  begin program iteration number 2
     CreateKSP(myksp2);
     PetscOptionsSetValue("-a", "5");
     PetscOptionsSetValue("-c", "5");
     KSPSolve(myksp2);
     DestroyKSP(myksp2);
  end program iteration number 2

  begin program iteration number 3
     CreateKSP(myksp3);
     PetscOptionsSetValue("-a", "10");
     PetscOptionsSetValue("-b", "20");
     KESPSolve(myksp3);
     DestroyKSP(myksp3);
   end program iteration number 3
end program

In the iteration 2 appears the option "-c", what can I do to remove the
option "-b" inside the internal PETSc option database?
And similar, in the iteration 3 the option "-c" disappears and the option
"-b" returns with a different value. What can I do to remove the option "-c"
inside the internal PETSc option database?

Is there a routine that reset/empty completely the internal PETSc database
option without terminate the program? Or the only way is to assign a
different prefix for every program iteration?

Thanks very much in advance,
Cheers!

--
Filippo SPIGA, MSc Computer Science
~ homepage: http://tinyurl.com/fspiga ~

«Nobody will drive us out of Cantor's paradise.»
    -- David Hilbert

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On Fri, Dec 10, 2010 at 2:09 PM, Jed Brown <jed at 59a2.org> wrote:

> On Fri, Dec 10, 2010 at 19:54, Filippo Spiga <
> filippo.spiga at disco.unimib.it> wrote:
>
>> I know that it is possible to use API to set parameters (KSPSetType,
>> SNESSetType). But a lot of options of HYPRE or SUPERLU for example have no
>> API. Instead of mix option from command-line and API I would like to put
>> everything in a config file
>
>
> You might be interested in the -options_file command line option and
> PetscOptionsInsertFile.  Also, any options present in
>
> ~/.petscrc
> .petscrc (in current directory)
> petscrc (in current directory)
>
> get slurped in automatically, as well as the string in the PETSC_OPTIONS
> environment variable.
>
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