[petsc-users] Drastic increase in memory usage between DMDA_STENCIL_BOX and DMDA_STENCIL_STAR

[Mani Chandra]

I meant to say that since its a serial computation, I have all the
information on the same node and I am not exchanging data with another
node. I wanted to know if DMDA_STENCIL_BOX would also change the jacobian
structure. Looks like it does.


On Tue, Mar 18, 2014 at 9:14 PM, Barry Smith <bsmith at mcs.anl.gov> wrote:

>
> On Mar 18, 2014, at 8:04 PM, Mani Chandra <mc0710 at gmail.com> wrote:
>
> > Hi,
> >
> > I see a 4x increase in the memory usage when I change from
> DMDA_STENCIL_STAR to DMDA_STENCIL_BOX. Attached are the outputs of
> -log_summary which shows a huge increase in the matrix memory usage. Is
> this expected?
> >
> > On a different note, suppose I am running a serial calculation with no
> need to exchange data but I am using corner node information,
>
>    How can you use corner node information if you are not exchanging it?
> You will be using incorrect data
>
>
> > do I need to use DMDA_STENCIL_BOX? Would the jacobian when computed
> using colored finite differences be correctly represented if I use corner
> information but still use DMDA_STENCIL_STAR?
> >
> > Thanks,
> > Mani
> >
> >
> > <dmda_stencil_box.txt><dmda_stencil_star.txt>
>
>
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