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<div class="moz-cite-prefix">Am 04.09.2012 17:20, schrieb Matthew
Knepley:<br>
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<blockquote
cite="mid:CAMYG4GkP2A83XaDQ1nff-=ST+U+MLFFq51Kw=MmaFB6v_bPTzQ@mail.gmail.com"
type="cite">On Tue, Sep 4, 2012 at 9:52 AM, Thomas Witkowski <span
dir="ltr"><<a moz-do-not-send="true"
href="mailto:thomas.witkowski@tu-dresden.de" target="_blank">thomas.witkowski@tu-dresden.de</a>></span>
wrote:<br>
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<div><a moz-do-not-send="true"
href="http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/Mat/MATNEST.html"
target="_blank">http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/Mat/MATNEST.html</a></div>
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As I wrote in my initial question, each rank contains one
and only one seqaij matrix, which all should be joined to
one global matrix such that each local matrix is the
corresponding diagonal block of the mpiaij matrix. I think,
this does not work with nested matrices?<br>
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<div>Why does this not work? I really think you are making this
harder than it has to be.</div>
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Mh, maybe I have an incomplete view of the possibilities how to use
nested matrices.<br>
<br>
To become more specific: In the case of two mpi tasks, each
containing one seqaij matrix, how to call MatCreateNest? Is this
correct:<br>
<br>
Mat A;<br>
MatCreaeteNest(PETSC_COMM_WORLD, 2, PETSC_NULL, 2, PETSC_NULL, V
,&A);<br>
<br>
and V is defined on rank 0 as<br>
<br>
Mat V[2] = {seqMat, PETSC_NULL} ;<br>
<br>
and and rank 1 as<br>
<br>
Mat V[2] = {PETSC_NULL, seqMat};<br>
<br>
<br>
Thomas<br>
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cite="mid:CAMYG4GkP2A83XaDQ1nff-=ST+U+MLFFq51Kw=MmaFB6v_bPTzQ@mail.gmail.com"
type="cite">
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<div> Matt</div>
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<div text="#000000" bgcolor="#FFFFFF"> Thomas<br>
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<div> </div>
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<div>Hong<br>
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<blockquote type="cite"> <br>
<div class="gmail_quote">Thomas :<br>
<blockquote class="gmail_quote"
style="margin:0 0 0
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solid;padding-left:1ex">In my
FETI-DP code, each rank creates
a SEQAIJ matrix that represents
the discretization of the
interior domain. Just for
debugging, I would like to join
these sequential matrices to one
global MPIAIJ matrix. This
matrix has no off diagonal nnzs
and should be stored
corresponding to the ranks
unknowns, thus, first all rows
of the first rank and so on.
What's the most efficient way to
do this? Is it possible to
create this parallel matrix just
as a view of the sequential
ones, so without copying the
data? Thanks for any advise.</blockquote>
<div><br>
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<div><a moz-do-not-send="true"
href="http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/Mat/MatCreateMPIAIJConcatenateSeqAIJ.html"
target="_blank">http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/Mat/MatCreateMPIAIJConcatenateSeqAIJ.html</a></div>
<div><br>
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<div>Note: entries in seqaij
matrices are copied into a
mpiaij matrix without</div>
<div>inter-processor
communication. Use petsc-3.3 for
this function.</div>
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The function does not do what I expect.
For example, if we have two mpi task and
each contains one local square matrix with
n rows, I want to create a global square
matrix with 2n rows. This function create
a non-square matrix of size 2n x n.<span><font
color="#888888"><br>
<br>
Thomas<br>
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-- <br>
What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to
which their experiments lead.<br>
-- Norbert Wiener<br>
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