To keep the stencil small for matrix preallocation, you can create two DMDAs. On Jan 6, 2012 9:07 PM, "Barry Smith" <bsmith at mcs.anl.gov> wrote:
> > On Jan 6, 2012, at 4:43 PM, Xuefeng Li wrote: > > > On Fri, 6 Jan 2012, Matthew Knepley wrote: > > > >> On Fri, Jan 6, 2012 at 4:32 PM, Xuefeng Li <li at loyno.edu> wrote: > >> > >>> However, is there a way to change/adjust the stencil width > >>> AFTER the DA has been created and set up to a DMMG? Or, > >>> in general, can we attach different DA objects to a DMMG > >>> at different times? > >>> > >> > >> 1) You cannot change this after setting up the DA. Just make another DA, > >> since > >> they are very lightweight. > >> > >> 2) I think structuring new code around DMMG is wrong. It has been > removed in > >> petsc-dev and is deprecated in 3.2. What are you trying to do? > >> > > I am just trying to use the ghost points to share > > data among neighboring processes at one step > > during the whole iteration. At that particular > > step, the stencil width needs to be bigger. > > > > One can always set the stencil width to be big > > enough so that one does not need to adjust it. > > But this is just not as efficient as it can be. > > Just create a bigger-stencil DMDA that you use during those "special" > steps. > > Barry > > > > > Thanks again. > > > > Regards, > > > > --Xuefeng Li, (504)865-3340(phone) > > Like floating clouds, the heart rests easy > > Like flowing water, the spirit stays free > > http://www.loyno.edu/~li/home > > New Orleans, Louisiana (504)865-2051(fax) > > > > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20120108/55f99085/attachment.htm>
