[petsc-users] Field split questions

[Colin McAuliffe]

Thanks all, regarding use of DM in 3.3, is the procedure now to create  
the fields with PCFieldSplitSetIS and then use  
DMCreateFieldDecompositionDM to create a new DM based from the new  
fields and the DM for the original problem?

Colin

Quoting Matthew Knepley <knepley at gmail.com>:

> On Wed, Aug 8, 2012 at 9:12 PM, Barry Smith <bsmith at mcs.anl.gov> wrote:
>
>>
>> On Aug 8, 2012, at 9:08 PM, Satish Balay <balay at mcs.anl.gov> wrote:
>>
>> > Barry - you forgot to commit/push the interface files in
>> > src/ksp/pc/impls/fieldsplit/ftn-custom.
>>
>>     Thanks. I forgot to hg add the new files :-(
>>
>> >
>> > http://petsc.cs.iit.edu/petsc/petsc-dev/rev/40f9515d8b01
>> >
>> > Perhaps this interface addition can go into petsc-3.3?
>>
>>     No
>>
>> >
>> > That patch [with a minor fix] can be easily applied to petsc-3.1 to
>> > get the link working. [old iffy functionality is a different matter :)]
>>
>>    Users are free to shot themselves in the foot if they want to so Colin
>> certainly could back-port this but I recommend upgrading.
>
>
> Colin, I also recommend upgrading since with the new stuff, you should be
> able to do everything you want
> to do from the command line without messing around pulling out KSP objects.
>
>    Matt
>
>
>>
>>    Barry
>>
>> >
>> > Satish
>> >
>> > On Wed, 8 Aug 2012, Barry Smith wrote:
>> >
>> >>
>> >>  Well the field split stuff in 3.1 is rather iffy anyways.   You really
>> need to take the couple hours and do the upgrade before trying to add new
>> features to the fortran code you are using.  The time to upgrade will be
>> much less than time spent in work arounds.
>> >>
>> >>    Barry
>> >>
>> >> On Aug 8, 2012, at 8:52 PM, Colin McAuliffe <cjm2176 at columbia.edu>
>> wrote:
>> >>
>> >>> Is there an alternative to this routine that will allow me to define
>> hierarchical field splits in 3.1p8? It will be a fairly significant
>> undertaking to upgrade the fortran code I am using to be compatible with
>> newer versions of petsc.
>> >>>
>> >>> Colin
>> >>>
>> >>> Quoting Barry Smith <bsmith at mcs.anl.gov>:
>> >>>
>> >>>>
>> >>>>  Colin,
>> >>>>
>> >>>>   I'm sorry we never had a FORTRAN interface for this routine.
>>  You'll need to switch to petsc-dev
>> http://www.mcs.anl.gov/petsc/developers/index.html to use that  function.
>> >>>>
>> >>>>   Barry
>> >>>>
>> >>>>
>> >>>> On Aug 8, 2012, at 7:54 PM, Colin McAuliffe <cjm2176 at columbia.edu>
>> wrote:
>> >>>>
>> >>>>> Thanks I will look into DM. Is PCFieldSplitGetSubKSP in petsc
>>  version 3.1p8 callable from fortran? I am getting the following  error
>> when I compile the fortran code, and I cant figure out if  this is an error
>> in my code or what.
>> >>>>>
>> >>>>> Undefined symbols for architecture x86_64:
>> >>>>> "_pcfieldsplitgetsubksp_", referenced from:
>> >>>>>    _umacr6_ in umacr6.o
>> >>>>> ld: symbol(s) not found for architecture x86_64
>> >>>>>
>> >>>>>
>> >>>>> thanks
>> >>>>> Colin
>> >>>>>
>> >>>>>
>> >>>>> Quoting Matthew Knepley <knepley at gmail.com>:
>> >>>>>
>> >>>>>> On Wed, Aug 8, 2012 at 8:48 AM, Colin McAuliffe  <
>> cjm2176 at columbia.edu>wrote:
>> >>>>>>
>> >>>>>>> Hello all,
>> >>>>>>>
>> >>>>>>> When using PCFieldSplitSetIS to define splits within splits,
>> should the IS
>> >>>>>>> contain indices in the original matrix or in the next highest
>> split level?
>> >>>>>>>
>> >>>>>>
>> >>>>>> The next highest split level. You might consider using a DM if you
>> have
>> >>>>>> some structure (like discretization on a mesh).
>> >>>>>> This should handle all the index-wrangling for you. It is new, but
>> intended
>> >>>>>> for just this kind of thing.
>> >>>>>>
>> >>>>>> Also, my matrix is in aij format but one of the sub fields has a
>> block
>> >>>>>>> diagonal structure. Is it still possible use block jacobi on this
>> field?
>> >>>>>>>
>> >>>>>>
>> >>>>>> Yes.
>> >>>>>>
>> >>>>>> Matt
>> >>>>>>
>> >>>>>>
>> >>>>>>> Thanks and all the best
>> >>>>>>> Colin
>> >>>>>>>
>> >>>>>>>
>> >>>>>>>
>> >>>>>>>
>> >>>>>>> --
>> >>>>>>> Colin McAuliffe
>> >>>>>>> PhD Candidate
>> >>>>>>> Columbia University
>> >>>>>>> Department of Civil Engineering and Engineering Mechanics
>> >>>>>>>
>> >>>>>>
>> >>>>>>
>> >>>>>>
>> >>>>>> --
>> >>>>>> 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
>> >>>>>>
>> >>>>>
>> >>>>>
>> >>>>>
>> >>>>> --
>> >>>>> Colin McAuliffe
>> >>>>> PhD Candidate
>> >>>>> Columbia University
>> >>>>> Department of Civil Engineering and Engineering Mechanics
>> >>>>
>> >>>>
>> >>>>
>> >>>
>> >>>
>> >>>
>> >>> --
>> >>> Colin McAuliffe
>> >>> PhD Candidate
>> >>> Columbia University
>> >>> Department of Civil Engineering and Engineering Mechanics
>> >>
>> >>
>> >
>>
>>
>
>
> --
> 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
>



-- 
Colin McAuliffe
PhD Candidate
Columbia University
Department of Civil Engineering and Engineering Mechanics