[petsc-users] DMNetworkGetEdgeRange() in parallel

Mon Feb 23 09:27:51 CST 2015

I'm iterating through local edges given in DMNetworkGetEdgeRange(). For
each edge, I extract or modify its corresponding value in a global petsc
vector. Therefore that vector must have as many components as edges there
are in the network. To extract the value in the vector, I use VecGetArray()
and a variable counter that is incremented in each iteration. The array
that I obtain in VecGetArray() has to be the same size than the edge range.
That variable counter starts as 0, so if the array that I obtained in
VecGetArray() is x_array, x_array[0] must be the component in the global
vector that corresponds with the start edge given in DMNetworkGetEdgeRange()

I need that global petsc vector because I will use it in other operations,
it's not just data. Sorry for the confusion. Thanks in advance.

Miguel

On Mon, Feb 23, 2015 at 9:09 AM, Matthew Knepley <knepley at gmail.com> wrote:

> On Mon, Feb 23, 2015 at 8:42 AM, Miguel Angel Salazar de Troya <
> salazardetroya at gmail.com> wrote:
>
>> Thanks, that will help me. Now what I would like to have is the
>> following: if I have two processors and ten edges, the partitioning results
>> in the first processor having the edges 0-4 and the second processor, the
>> edges 5-9. I also have a global vector with as many components as edges,
>> 10. How can I partition it so the first processor also has the 0-4
>> components and the second, the 5-9 components of the vector?
>>
> I think it would help to know what you want to accomplish. This is how you
> are proposing to do it.'
>
> If you just want to put data on edges, DMNetwork has a facility for that
> already.
>
>   Thanks,
>
>      Matt
>
>
>> Miguel
>> On Feb 23, 2015 8:08 AM, "Abhyankar, Shrirang G." <abhyshr at mcs.anl.gov>
>> wrote:
>>
>>>  Miguel,
>>>    One possible way is to store the global numbering of any edge/vertex
>>> in the "component" attached to it. Once the mesh gets partitioned, the
>>> components are also distributed so you can easily retrieve the global
>>> number of any edge/vertex by accessing its component. This is what is done
>>> in the DMNetwork example pf.c although the global numbering is not used for
>>> anything.
>>>
>>>  Shri
>>>  From: Matthew Knepley <knepley at gmail.com>
>>> Date: Mon, 23 Feb 2015 07:54:34 -0600
>>> To: Miguel Angel Salazar de Troya <salazardetroya at gmail.com>
>>> Cc: "petsc-users at mcs.anl.gov" <petsc-users at mcs.anl.gov>
>>> Subject: Re: [petsc-users] DMNetworkGetEdgeRange() in parallel
>>>
>>>   On Sun, Feb 22, 2015 at 3:59 PM, Miguel Angel Salazar de Troya <
>>> salazardetroya at gmail.com> wrote:
>>>
>>>> Thanks. Once I obtain that Index Set with the routine DMPlexCreateCellNumbering()
>>>> (I assume that the edges in DMNetwork correspond to cells in DMPlex) can I
>>>> use it to partition a vector with as many components as edges I have in my
>>>> network?
>>>>
>>>
>>>  I do not completely understand the question.
>>>
>>>  If you want a partition of the edges, you can use
>>> DMPlexCreatePartition() and its friend DMPlexDistribute(). What
>>> are you trying to do?
>>>
>>>     Matt
>>>
>>>
>>>>  Thanks
>>>> Miguel
>>>>
>>>> On Sun, Feb 22, 2015 at 12:15 PM, Matthew Knepley <knepley at gmail.com>
>>>> wrote:
>>>>
>>>>>  On Sun, Feb 22, 2015 at 11:01 AM, Miguel Angel Salazar de Troya <
>>>>> salazardetroya at gmail.com> wrote:
>>>>>
>>>>>> Hi
>>>>>>
>>>>>>  I noticed that the routine DMNetworkGetEdgeRange() returns the
>>>>>> local indices for the edge range. Is there any way to obtain the global
>>>>>> indices? So if my network has 10 edges, the processor 1 has the 0-4 edges
>>>>>> and the processor 2, the 5-9 edges, how can I obtain this information?
>>>>>>
>>>>>
>>>>>  One of the points of DMPlex is we do not require a global numbering.
>>>>> Everything is numbered
>>>>> locally, and the PetscSF maps local numbers to local numbers in order
>>>>> to determine ownership.
>>>>>
>>>>>  If you want to create a global numbering for some reason, you can
>>>>> using DMPlexCreatePointNumbering().
>>>>> There are also cell and vertex versions that we use for output, so you
>>>>> could do it just for edges as well.
>>>>>
>>>>>    Thanks,
>>>>>
>>>>>       Matt
>>>>>
>>>>>
>>>>>>  Thanks
>>>>>>  Miguel
>>>>>>
>>>>>>  --
>>>>>>  *Miguel Angel Salazar de Troya*
>>>>>> Graduate Research Assistant
>>>>>> Department of Mechanical Science and Engineering
>>>>>> University of Illinois at Urbana-Champaign
>>>>>> (217) 550-2360
>>>>>> salaza11 at illinois.edu
>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>>  --
>>>>> 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
>>>>>
>>>>
>>>>
>>>>
>>>>  --
>>>>  *Miguel Angel Salazar de Troya*
>>>> Graduate Research Assistant
>>>> Department of Mechanical Science and Engineering
>>>> University of Illinois at Urbana-Champaign
>>>> (217) 550-2360
>>>> salaza11 at illinois.edu
>>>>
>>>>
>>>
>>>
>>>  --
>>> 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
>

-- 
*Miguel Angel Salazar de Troya*
Graduate Research Assistant
Department of Mechanical Science and Engineering
University of Illinois at Urbana-Champaign
(217) 550-2360
salaza11 at illinois.edu
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