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<div dir="ltr" class="m_-4343991669698257482gmail_attr">On Tue, Jan 22, 2019 at 1:35 PM Matthew Knepley <<a href="mailto:knepley@gmail.com" target="_blank">knepley@gmail.com</a>> wrote:<br>
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<div dir="ltr">On Tue, Jan 22, 2019 at 2:23 PM Zhang, Junchao via petsc-dev <<a href="mailto:petsc-dev@mcs.anl.gov" target="_blank">petsc-dev@mcs.anl.gov</a>> wrote:<br>
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<div>I want to add root values to leaves, and keep root unchanged. PetscSFBcast came to my mind, but unfortunately it only broadcasts roots and does not have an MPI_Op argument like PetscSFReduce for me to choose from INSERT_VALUES, ADD_VALUES, etc.</div>
<div>Any tips? Thanks.</div>
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<div>PS: I met this problem when I tried to implement VecScatter in SF. In VecScatter, multiple entries of vec x can be scattered to the same entry of vec y, and one entry of x can also be scattered to multiple entries of y. I want to use one SF for all combinations
of SCATTER_FORWARD/BACKWARD, INSERT/ADD_VALUES. It seems impossible with current SF interface.</div>
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<div>I think you might want this: <a href="https://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/PetscSF/PetscSFFetchAndOpBegin.html" target="_blank">https://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/PetscSF/PetscSFFetchAndOpBegin.html</a></div>
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<div>I read it as: Leaves are accumulated to root (root is changed), and leaves get a snapshot of the root before each atomic update. It is not what I want.</div>
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<div> Thanks,</div>
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<div> Matt</div>
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<div>--Junchao Zhang<br>
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<div>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</div>
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<div><a href="http://www.cse.buffalo.edu/~knepley/" target="_blank">https://www.cse.buffalo.edu/~knepley/</a><br>
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