[petsc-users] query DMPlexCreateSection

[Matthew Knepley]

On Thu, Jan 2, 2014 at 9:56 AM, Matthew Knepley <knepley at gmail.com> wrote:

> On Thu, Jan 2, 2014 at 4:11 AM, Dharmendar Reddy <dharmareddy84 at gmail.com>wrote:
>
>> Hello,
>>          I am trying to use DMPlexCreateSection from fortran. I was
>> able to solve a Poisson equation earlier using DMPlex for handling
>> mesh data.
>>
>> Now i need to solve a system of equations: (poisson + continuity
>> equations)
>>
>> - div (grad phi) = (C + n)  --- (1)
>>   div (J ) = 0  ---------------  (2)
>>   J = n grad(phi)
>> ( C is constant)
>> Simulation domain is defined as, rectangular regions 1 and 2 shown below.
>>
>> -------------
>> |     1        |
>> -------------
>> |               |
>> |       2      |
>> |               |
>> --------------
>>
>> Now, equation 1 is defined in region 1 and 2
>> and equation 2 is defined only for region 2.
>>
>> How do i setup the section  ? DMPlexCreateSection applies the given
>> DOF layout  per cell to all cells in the mesh.
>>
>> I am not sure if all the function calls inside
>> DMPlexCreateSectionIntial and DMPlexCreateSectionBCDof  are accessible
>> from Fotran.
>>
>
> You don't want them anyway since they apply to the whole domain. The
> control flow could be:
>

Replace DMPlex with PetscSection. I am tired.

  Thanks,

     Matt


>   DMPlexSetChart()
>   <loop over region 1>
>     DMPlexSetDof() and DMPlexSetFieldDof()
>   <loop over region 2>
>     DMPlexSetDof() and DMPlexSetFieldDof()
>   <loop over BC>
>     DMPlexSetConstraintDof() and DMPlexSetFieldConstraintDof()
>   DMPlexSetUp()
>   <loop over BC>
>     DMPlexSetConstraintIndices() and DMPlexSetFieldConstraintIndices()
>
> We could try and package some of this up if it looks generic.
>
>   Thanks,
>
>      Matt
>
>
>> Thanks
>> Reddy
>>
>> --
>> -----------------------------------------------------
>> Dharmendar Reddy Palle
>>
>
>
>
> --
> 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
>



-- 
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
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