On 21/11/2015 9:58 PM, Matthew Knepley wrote:
On Sat, Nov 21, 2015 at 7:47 AM, TAY wee-beng <[email protected]
<mailto:[email protected]>> wrote:
On 10/11/2015 8:47 PM, Matthew Knepley wrote:
On Tue, Nov 10, 2015 at 6:30 AM, TAY wee-beng <[email protected]
<mailto:[email protected]>> wrote:
On 10/11/2015 8:27 PM, Matthew Knepley wrote:
On Tue, Nov 10, 2015 at 3:27 AM, TAY wee-beng
<[email protected] <mailto:[email protected]>> 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.
No.
Hi,
Another qn is supposed the sta_ijk_uniform and end_ijk_uniform change
every time step. Hence I need to destroy the DM etc and re-create at
each time step.
If that's the case, will this slow down my code?
Thanks.
Next qn is whether if I can call DMDAVecGetArrayF90 at the start,
and DMDAVecRestoreArrayF90 after operations similar to the one
above is finished.
You cannot do other Vec operations before you call Restore.
Matt
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
--
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
