[petsc-users] Bug when multipling a SBAIJ matrix with a vector

[Barry Smith]

   Hong and Shri,

    It looks like in a couple places (like MatMult_SeqSBAIJ_1) we have the assumption all diagonal entires exist (likely my fault). But usually we do not assume this.  Could you please fix MatMult_SeqSBAIJ_1 and check for other places with this assumption?

    Thanks

     Barry

In the MatSOR() for SBAIJ I would advocate generating an error message if a diagonal doesn't exist, this could also be done in the factorizations if it makes the code simplier.


On Oct 21, 2010, at 3:59 AM, Andreas Hauffe wrote:

> Hi,
> 
> I think there is a bug when multiplying an SBAIJ matrix with a vector, if the 
> matrix has a zero/missing row. I tried to write a small example:
> |x x| |1| = |0|
> |x 1| |x|    |0|
> The result since 3.1 is:
> |x x| |1| = |1|
> |x 1| |x|    |0|
> 
> I add the fortran code:
> program main
> 
>  implicit none
> 
> #include "finclude/petscsys.h"
> #include "finclude/petscvec.h"
> #include "finclude/petscvec.h90"
> #include "finclude/petscmat.h"
> #include "finclude/petscmat.h90"
> 
>  Mat            :: KaaS
>  Vec            :: v0,y
>  PetscInt       :: m
>  PetscInt       :: bs
> 
>  PetscErrorCode :: ierr
> 
>  call petscInitialize(PETSC_NULL_CHARACTER,ierr); CHKERRQ(ierr)
> 
>  m  = 2
>  bs = 1
>  call MatCreate(PETSC_COMM_WORLD,KaaS,ierr); CHKERRQ(ierr)
>  call MatSetSizes(KaaS,PETSC_DECIDE,PETSC_DECIDE,m,m,ierr); CHKERRQ(ierr)
>  call MatSetType(KaaS,MATSEQSBAIJ,ierr); CHKERRQ(ierr)
> !  call MatSetType(KaaS,MATAIJ,ierr); CHKERRQ(ierr)
>  call MatSetFromOptions(KaaS,ierr); CHKERRQ(ierr)
> 
> !  call MatSetValue(KaaS, 0, 0, 0.d0, ADD_VALUES, ierr); CHKERRQ(ierr)
>  call MatSetValue(KaaS, 1, 1, 1.d0, ADD_VALUES, ierr); CHKERRQ(ierr)
> 
>  call MatAssemblyBegin(KaaS,MAT_FINAL_ASSEMBLY,ierr); CHKERRQ(ierr)
>  call MatAssemblyEnd  (KaaS,MAT_FINAL_ASSEMBLY,ierr); CHKERRQ(ierr)
> 
>  call MatGetVecs(KaaS,y,v0,ierr); CHKERRQ(ierr)
>  call VecSetValue(v0,0,1.D0,INSERT_VALUES,ierr); CHKERRQ(ierr)
>  call MatMult(KaaS,v0,y,ierr); CHKERRQ(ierr)
>  call VecView(y,PETSC_NULL_OBJECT,ierr); CHKERRQ(ierr)
> 
>  call VecDestroy(y,ierr); CHKERRQ(ierr)
>  call VecDestroy(v0,ierr); CHKERRQ(ierr)
>  call MatDestroy(KaaS,ierr); CHKERRQ(ierr)
> 
>  call petscFinalize(ierr)
> 
> end program main
> 
> 
> best
> -- 
> Andreas Hauffe
> 
> ----------------------------------------------------------------------------------------------------
> Technische Universität Dresden
> Institut für Luft- und Raumfahrttechnik / Institute of Aerospace Engineering
> Lehrstuhl für Luftfahrzeugtechnik / Chair of Aircraft Engineering
> 
> D-01062 Dresden
> Germany
> 
> phone   : (++49)351 463 38496
> fax     : (++49)351 463 37263
> mail    : andreas.hauffe at tu-dresden.de
> Website : http://tu-dresden.de/mw/ilr/lft
> ----------------------------------------------------------------------------------------------------