[petsc-users] DMShellSetCreateRestriction

[Barry Smith]

  Boris,

    We will add this support to the DMShell and its usage from PCMG within a few days.

   Barry

> On Mar 11, 2016, at 3:39 PM, Boris Kaus <kaus at uni-mainz.de> wrote:
> 
> 
>> On Mar 11, 2016, at 8:53 PM, Matthew Knepley <knepley at gmail.com> wrote:
>> 
>> On Fri, Mar 11, 2016 at 12:26 PM, Dave May <dave.mayhem23 at gmail.com> wrote:
>> On 11 March 2016 at 18:11, anton <popov at uni-mainz.de> wrote:
>> Hi team,
>> 
>> I'm implementing staggered grid in a PETSc-canonical way, trying to build a custom DM object, attach it to SNES, that should later transfered it further to KSP and PC.
>> 
>> Yet, the Galerking coarsening for staggered grid is non-symmetric. The question is how possible is it that DMShellSetCreateRestriction can be implemented and included in 3.7 release?
>> 
>> It's a little more work than just adding a new method within the DM and a new APIs for DMCreateRestriction() and DMShellSetCreateRestriction().
>> PCMG needs to be modified to call DMCreateRestriction(). 
>> 
>> Dave is correct. Currently, PCMG only calls DMCreateInterpolation(). We would need to add a DMCreateRestriction() call.
> The PCMG object already uses a restriction operator that is different from the interpolation parameter if it is specified with PCMGSetRestriction. 
> For consistency, one would expect a similar DMCreateRestriction object, not? I realize that this is not relevant for FEM codes, but for staggered FD it makes quite some difference. 
> 
> Other suggestions on how to best integrate staggered finite differences within the current PETSc framework are ofcourse also highly welcome. 
> Our current thinking was to pack it into a DMSHELL (which has the problem of not having a restriction interface). 
> 
> thanks,
> Boris
> 
> 
> 
> 
>>   Thanks,
>> 
>>     Matt
>>  
>> Please, please.
>> 
>> Thanks,
>> Anton
>> 
>> 
>> -- 
>> What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead.
>> -- Norbert Wiener
>