[petsc-users] DMNetworkGetEdgeRange() in parallel

Mon Feb 23 10:46:02 CST 2015

Yes, that's what I need. If I added a variable to the edges with
DMNetworkAddNumVariables
<http://www.mcs.anl.gov/petsc/petsc-master/docs/manualpages/DM/DMNetworkAddNumVariables.htmlhttp://www.mcs.anl.gov/petsc/petsc-master/docs/manualpages/DM/DMNetworkAddNumVariables.htmlhttp://www.mcs.anl.gov/petsc/petsc-master/docs/manualpages/DM/DMNetworkAddNumVariables.html>(),
my global vector that DMCreateGlobalVector
<http://www.mcs.anl.gov/petsc/petsc-master/docs/manualpages/DM/DMCreateGlobalVector.html>()
creates would have the edge variables that I don't want to have mixed with
the variables I added in the vertices. I want them to be in a separate
vectors. Therefore, I create a vector with  DMCreateGlobalVector
<http://www.mcs.anl.gov/petsc/petsc-master/docs/manualpages/DM/DMCreateGlobalVector.html>()
with
the variables I added in the vertices. Now I want another vector with
"other" variables in the edges, and this vector has to be partitioned the
same way the edges are.

Thanks
Miguel

On Mon, Feb 23, 2015 at 10:33 AM, Abhyankar, Shrirang G. <
abhyshr at mcs.anl.gov> wrote:

>  Miguel,
>   It's not entirely clear what you are trying to do and what solver you
> intend to use eventually. The way DMNetwork is set up currently (following
> from DMPlex) is that you can assign degrees of freedom for each vertex and
> edge using DMNetworkAddNumVariables
> <http://www.mcs.anl.gov/petsc/petsc-master/docs/manualpages/DM/DMNetworkAddNumVariables.htmlhttp://www.mcs.anl.gov/petsc/petsc-master/docs/manualpages/DM/DMNetworkAddNumVariables.htmlhttp://www.mcs.anl.gov/petsc/petsc-master/docs/manualpages/DM/DMNetworkAddNumVariables.html>.
> Once the DM is setup and/or distributed, one create global vector(s) of the
> appropriate size using DMCreateGlobalVector
> <http://www.mcs.anl.gov/petsc/petsc-master/docs/manualpages/DM/DMCreateGlobalVector.html>.
> During a residual evaluation, one first gets the local vectors from the DM
> and then does a DMGlobalToLocalBegin/End
> <http://www.mcs.anl.gov/petsc/petsc-master/docs/manualpages/DM/DMGlobalToLocalBegin.html> to
> copy the contents of the global vector to the local vector. You can then
> use a VecGetArray() on this local vector to access the elements of the
> vector. While iterating over the local edges/vertices,
> DMNetworkGetVariableOffset
> <http://www.mcs.anl.gov/petsc/petsc-master/docs/manualpages/DM/DMNetworkGetVariableOffset.html> gives
> you the location of the first element in the local vector for that
> particular edge/vertex point. This is how it is done in the DMNetwork
> example pf.c.
>
>  Now back to your question, are you creating your "global petsc vector"
> using DMCreateGlobalVector()? Do you wish to have vectors of different
> sizes associated with a DMNetwork?
>
>  Shri
>
>
>   From: Miguel Angel Salazar de Troya <salazardetroya at gmail.com>
> Date: Mon, 23 Feb 2015 09:27:51 -0600
> To: Matthew Knepley <knepley at gmail.com>
> Cc: Shri <abhyshr at mcs.anl.gov>, "petsc-users at mcs.anl.gov" <
> petsc-users at mcs.anl.gov>
>
> Subject: Re: [petsc-users] DMNetworkGetEdgeRange() in parallel
>
>  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
>
>

-- 
*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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