[petsc-users] Issue when passing DMDA array on to Paraview Catalyst

[Smith, Barry F.]

> On Mar 13, 2019, at 11:28 AM, Matthew Knepley via petsc-users <petsc-users at mcs.anl.gov> wrote:
> 
> On Wed, Mar 13, 2019 at 12:16 PM Bastian Löhrer via petsc-users <petsc-users at mcs.anl.gov> wrote:
> Dear PETSc users,
> 
> I am having difficulties passing PETSc data on to Paraview Catalyst and 
> it may be related to the way we handle the PETSs data in our Fortran code.
> 
> We have DMDA objects, which we pass on to subroutines this way:
> 
> >   ...
> >   call DMCreateLocalVector(da1dof, loc_p, ierr)
> >   ...
> >   call VecGetArray(loc_p, loc_p_v, loc_p_i, ierr)
> >   call process( loc_p_v(loc_p_i+1) )
> >   ...
> >
> 
> Inside the subroutine (process in this example) we treat the 
> subroutine's argument as if it were an ordinary Fortran array:
> 
> >   subroutine process( p )
> >
> >     use gridinfo ! provides gis, gie, ... etc.
> >
> >     implicit none
> >
> > #include "petsc_include.h"
> >
> >     PetscScalar, dimension(gis:gie,gjs:gje,gks:gke) :: p
> >     PetscInt i,j,k
> >
> >     do k = gks, gke
> >       do j = gjs, gje
> >         do i = gis, gie
> >
> >             p(i,j,k) = ...
> >
> >         enddo
> >       enddo
> >     enddo
> >
> >   end subroutine process
> >
> I find this procedure a little quirky, but it has been working 
> flawlessly for years.
> 
> However, I am now encountering difficulties when passing this 
> variable/array p on to a Paraview Catalyst adaptor subroutine. Doing so 
> I end up with very strange values there. When replacing p with an 
> ordinary local Fortran array everything is fine.
> 
> I can't think of a reason it would not work. I would look at the pointer you get inside
> the Catalyst function using the debugger.
> 
> Note that you can also get an F90 array out if that is what Catalyst needs.

  VecGetArrayF90() or DMDAVecGetArrayF90()
> 
>   Thanks,
> 
>      Matt
>  
> Bastian
> -- 
> What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead.
> -- Norbert Wiener
> 
> https://www.cse.buffalo.edu/~knepley/