[petsc-dev] checking if a vector is ghosted

[Barry Smith]

  We should add a VecIsGhosted()

   Barry

On Nov 8, 2011, at 12:07 PM, Jed Brown wrote:

> On Tue, Nov 8, 2011 at 14:05, Matthew Knepley <knepley at gmail.com> wrote:
> Just want to check that the following is a kosher use of the return error handler
> 
>    bool _is_ghosted = true;
>    PetscErrorCode ierr;
>    PetscPushErrorHandler(PetscReturnErrorHandler,PETSC_NULL);
>    ierr= VecGhostGetLocalForm(*x, x_ghosted.get());
>    if (ierr != 0 )
>      _is_ghosted = false;
>    PetscPopErrorHandler();
> 
> Do you need to mess with the error handler?
> 
> Yes, otherwise an error message would be printed.
> 
> Mark, what you describe is okay. We, or you, could make a VecIsGhosted(). The code shows how it determines whether a Vec is ghosted.
> 
> PetscErrorCode  VecGhostGetLocalForm(Vec g,Vec *l)
> {
>   PetscErrorCode ierr;
>   PetscBool      isseq,ismpi;
> 
>   PetscFunctionBegin;
>   PetscValidHeaderSpecific(g,VEC_CLASSID,1);
>   PetscValidPointer(l,2);
> 
>   ierr = PetscTypeCompare((PetscObject)g,VECSEQ,&isseq);CHKERRQ(ierr);
>   ierr = PetscTypeCompare((PetscObject)g,VECMPI,&ismpi);CHKERRQ(ierr);
>   if (ismpi) {
>     Vec_MPI *v  = (Vec_MPI*)g->data;
>     if (!v->localrep) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONG,"Vector is not ghosted");
>     *l = v->localrep;
>   } else if (isseq) {
>     *l = g;
>   } else {
>     SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONG,"Vector type %s does not have local representation",((PetscObject)g)->type_name);
>   }
>   ierr = VecGhostStateSync_Private(g,*l);CHKERRQ(ierr);
>   ierr = PetscObjectReference((PetscObject)*l);CHKERRQ(ierr);
>   PetscFunctionReturn(0);
> }