[petsc-dev] [petsc-maint #89809] 3D DMDAs in petsc-3.2

[Jed Brown]

On Sun, Oct 9, 2011 at 22:54, Barry Smith <bsmith at mcs.anl.gov> wrote:

>
>   Jed,
>
>       It appears your  some of your many
>
> if (s_t >= x*y*z) {s_t = bases[n26] + (i-1)*x_t;} /* 2d case */
>
> things are breaking the communication with a stencil width of 2
>

da3.c:980
M-x xhg-ann<RET>

Looks like that line comes from

changeset:   18790:4310a5aad280
user:        Ethan Coon <ecoon at lanl.gov>
date:        Wed Apr 20 00:57:49 2011 +0200
summary:     cruft to handle the special case of solving a 2D problem in a
3D algorithm with stencil size > 1.  This only works in the 3D case,
z-dimension

http://petsc.cs.iit.edu/petsc/petsc-dev/rev/4310a5a


> the second layer of ghost points uses the first layer instead of getting
> the second layer.
>
> Since I don't understand your /* 2d case */ business I leave it to you to
> fix
>

I don't understand it either and haven't tried. Maybe Ethan can take a look.
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