[petsc-users] PETSc DM ex13f90

praveen kumar praveen1bharadwaj at gmail.com
Tue May 3 07:25:16 CDT 2016


Thanks again, Asmund. You guessed it correct that I have misunderstood.
Things are clear now.

Regards,
Praveen

On Mon, May 2, 2016 at 11:53 PM, Åsmund Ervik <asmund.ervik at ntnu.no> wrote:

>
> >
> >Thanks a lot for such a lucid explanation. The note which you mentioned
> at the end is very important for me, as my code contains loops going from
> both 1 to N and 0 to N+1.
> >
>
> You're welcome.
>
> Just to avoid any potential misunderstanding: the note at the end was if
> you have loops over your "real" (non-ghost) variables going from 0 to N-1,
> i.e. zero indexing as in C, where the first index of your "real" values is
> 0, ghost values are at -1 and below and at N and above.
>
> On the other hand, if you have some loops from 1 to N and some loops from
> 0 to N+1, it means you have some loops over just the "real" variables (1 to
> N) and some loops over "real" + ghost variables (0 to N+1). In this case,
> you do not need to change the code. Just set the stencil width to 1 (or to
> 2 if your "widest" loop goes from -1 to N+2, etc.).
>
> (When I say "real", I don't mean as in real vs. complex numbers, but as in
> the grid point values that are not boundary conditions.)
>
> Regards,
> Åsmund




-- 
B. Praveen Kumar
Research Scholar,
Computational Combustion Lab,
Dept.of Aerospace Engg.
IIT Madras
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