On 10/11/2015 8:47 PM, Matthew Knepley wrote:
On Tue, Nov 10, 2015 at 6:30 AM, TAY wee-beng <zonexo@gmail.com> wrote:

On 10/11/2015 8:27 PM, Matthew Knepley wrote:
On Tue, Nov 10, 2015 at 3:27 AM, TAY wee-beng <zonexo@gmail.com> wrote:
Hi,

Inside my subroutine, I need to access the DA variable cu_types_array frequently.

So I need to call DMDAVecGetArrayF90 and DMDAVecRestoreArrayF90 before and after frequently.

Is this necessary? Can I call DMDAVecGetArrayF90 at the start and only call DMDAVecRestoreArrayF90 towards the end, where I don't need to modify the values of cu_types_array anymore?

Will this cause memory corruption?

You cannot use any other vector operations before you have called Restore.

Hi,

What do you mean by vector operations? I will just be doing some maths operation to change the values in cu_types_array. Is that fine?

While you have the array, no other operation can change the values.
Hi,

Let me clarify this. I declare in this way:

DM  da_cu_types

Vec cu_types_local,cu_types_global

PetscScalar,pointer :: cu_types_array(:,:,:)

call DMDACreate3d(MPI_COMM_WORLD,DM_BOUNDARY_NONE,DM_BOUNDARY_NONE,DM_BOUNDARY_NONE,DMDA_STENCIL_STAR,(end_ijk_uniform(1) - sta_ijk_uniform(1) + 1),(end_ijk_uniform(2) - sta_ijk_uniform(2) + 1),&

(end_ijk_uniform(3) - sta_ijk_uniform(3) + 1),PETSC_DECIDE,PETSC_DECIDE,PETSC_DECIDE,1,stencil_width_IIB,PETSC_NULL_INTEGER,PETSC_NULL_INTEGER,PETSC_NULL_INTEGER,da_cu_types,ierr)

call DMCreateGlobalVector(da_cu_types,cu_types_global,ierr)

call DMCreateLocalVector(da_cu_types,cu_types_local,ierr)

So when I need to change the values in DA variable cu_types, I call:

call DMDAVecGetArrayF90(da_cu_types,cu_types_local,cu_types_array,ierr)

.... math operations, changing the values of cu_types_array, such as:

cu_types_array = 0.d0

call DMDAVecRestoreArrayF90(da_cu_types,cu_types_local,cu_types_array,ierr)

1st of all, does these DMDAVecGetArrayF90 and DMDAVecRestoreArrayF90 take a lot of time, especially if I call them many times.

Next qn is whether if I can call DMDAVecGetArrayF90 at the start, and DMDAVecRestoreArrayF90 after operations similar to the one above is finished.

Thanks.

   Matt
 
 
Also, must the array be restored using DMDAVecRestoreArrayF90 before calling DMLocalToLocalBegin,DMLocalToLocalEnd?

Yes.

  Matt
 

--
Thank you.

Yours sincerely,

TAY wee-beng




--
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




--
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