Look at the source for DMDAVecGetArray() it calls either VecGetArray1d,
VecGetArray2d, VecGetArray3d. You can call the VecGetArrayNd directly setting
the local start and stop you want.
Thanks, I'll look into this.
As a PETSc developer, of course, I would recommend keeping your
local/temporary data also in Vecs and using the DMDAVecGetArray() for access to
those also and having all code written in the “local patch style” with loops
i=gxs; i<gxs+gxm I think the code is clearer and easier to reason about than
having each process from 0 to vxm etc.
Yeah, I definitely see the attraction and I may ultimately go that
route. As a non-PETSc developer however, it seems preferable to
absolutely minimize the reliance on PETSc data management for code
re-use in a non-PETSc application going forward. I'd be eager to hear
from other devs on how they approach this.
On 03/06/2014 09:23 AM, Barry Smith wrote:
On Mar 6, 2014, at 8:05 AM, Mark Lohry <[email protected]> wrote:
I'm using DMDAs for managing my DOF data on structured grids, so processes have
access to local array chunks from i=gxs; i<gxs+gxm. I have a lot of
local/temporary data that I don't want PETSc to manage and I'm trying to keep PETSc
as segregated from the rest of code as possible, so I'd prefer for any functions to
be ignorant of particular ordering, and just access from i=0; i<gxm so that I'm
using 0-indexed arrays locally. What's the appropriate way to go about doing this /
getting direct access to the beginning of global-indexed local array?
Mark,
Look at the source for DMDAVecGetArray() it calls either VecGetArray1d,
VecGetArray2d, VecGetArray3d. You can call the VecGetArrayNd directly setting
the local start and stop you want.
Barry
As a PETSc developer, of course, I would recommend keeping your local/temporary
data also in Vecs and using the DMDAVecGetArray() for access to those also and
having all code written in the “local patch style” with loops i=gxs; i<gxs+gxm
I think the code is clearer and easier to reason about than having each process
from 0 to vxm etc.
