[petsc-users] Call KSPConvergedDefault from Fortran

[Natacha BEREUX]

Dear PETSc users,


I am using PETSc  Fortran API.
I try to solve a linear system, and would like to define my own convergence
test.
More precisely, my convergence test calls the default convergence test
and then checks the true residual norm :
     subroutine MyKSPConverged(ksp,n,rnorm,flag,dummy,ierr)

      implicit none

#include <petsc/finclude/petscsys.h>
#include <petsc/finclude/petscvec.h>
#include <petsc/finclude/petscksp.h>

      KSP              ksp
      PetscErrorCode ierr
      PetscInt n,dummy
      KSPConvergedReason flag
      PetscReal rnorm, true_rnorm
      Vec true_res
      !
      call KSPConvergedDefault(ksp,n,rnorm,flag,PETSC_NULL_OBJECT,ierr)
      !
      ! If convergence test succeeds
       if ( (flag == KSP_CONVERGED_ATOL) .or.                           &
     &  (flag == KSP_CONVERGED_RTOL)) then
        ! Compute true residual
        call KSPBuildResidual( ksp , PETSC_NULL_OBJECT,                 &
     & PETSC_NULL_OBJECT, true_res, ierr )
        ! Compute true residual norm
        call VecNorm(true_res,NORM_2,true_rnorm,ierr)
        ! And check again convergence with respect to the true residual norm
        call KSPConvergedDefault(ksp,n,true_rnorm,flag,                 &
     & PETSC_NULL_OBJECT, ierr)
        ! Free memory
        call VecDestroy(true_res, ierr)
      endif
      !
      ierr = 0

      end

I get the following error message

[0]PETSC ERROR: --------------------- Error Message
--------------------------------------------------------------
[0]PETSC ERROR: Null argument, when expecting valid pointer
[0]PETSC ERROR: Convergence context must have been created with
KSPConvergedDefaultCreate()
[0]PETSC ERROR: See http://www.mcs.anl.gov/petsc/documentation/faq.html for
trouble shooting.
[0]PETSC ERROR: Petsc Release Version 3.6.2, Oct, 02, 2015

I understand that I should have  call KSPConvergedDefaultCreate() before
calling KSConvergedDefault( ....)

Am I right ?

If so what is the Fortran calling sequence for  KSPConvergedDefaultCreate ?
It is supposed to return a valid pointer and I don't succeed in doing so
from Fortran.

If you have any idea, I'd greatly appreciate it
Thank you!
Natacha


PS I have attached my code (it's a slightly modified version of ex2f.F
showing  the convergence test code )
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