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<p>Barry, <br>
<br>
Thanks for this quick answer. <br>
<br>
Best, <br>
Pierre <br>
</p>
<div class="moz-cite-prefix">Le 14/02/2023 à 21:35, Barry Smith a
écrit :<br>
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I have created an MR that documents this and moved the error
checking to a more appropriate location <a
href="https://gitlab.com/petsc/petsc/-/merge_requests/6070"
moz-do-not-send="true">https://gitlab.com/petsc/petsc/-/merge_requests/6070</a>
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<div>On Feb 14, 2023, at 4:33 AM, Pierre Bernigaud
<a class="moz-txt-link-rfc2396E" href="mailto:pierre.bernigaud@onera.fr"><pierre.bernigaud@onera.fr></a> wrote:</div>
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<p>Dear all, <br>
<br>
I hope this email finds you well. <br>
We are currently working on a solver which is
employing DMDA with SNES. The jacobian is computed
via FDColoring, ie: </p>
<p>call DMDACreate1D(PETSC_COMM_WORLD,
DM_BOUNDARY_GHOSTED, NY, NC, NGc,
PETSC_NULL_INTEGER, dmF, ierr)</p>
<p>! ----- Some steps ... </p>
<p>call DMCreateColoring(dmF, IS_COLORING_GLOBAL,
iscoloring, ierr)<br>
call MatFDColoringCreate(Jac,iscoloring,
matfdcoloring, ierr)<br>
call MatFDColoringSetFunction(matfdcoloring,
FormFunction, CTX, ierr)<br>
call MatFDColoringSetUp(Jac
,iscoloring,matfdcoloring, ierr)<br>
call SNESSetJacobian(snes, Jac, Jac,
SNESComputeJacobianDefaultColor, matfdcoloring,
ierr)</p>
<p>Everything is running smoothly. <br>
<span style="font-size: 10pt;">Recently, we modified
the boundary conditions such as to use periodic
BC: </span></p>
<p>call DMDACreate1D(PETSC_COMM_WORLD,
DM_BOUNDARY_PERIODIC, NY, NC, NGc,
PETSC_NULL_INTEGER, dmF, ierr)</p>
<p>We then encountered frequent crashes when calling
MatFDColoringSetUp, depending on the number of cells
NY. After looking for an solution, I found this old
thread: <a
href="https://lists.mcs.anl.gov/pipermail/petsc-users/2013-May/017449.html"
moz-do-not-send="true">https://lists.mcs.anl.gov/pipermail/petsc-users/2013-May/017449.html</a> <br>
It appears that when using periodic BC, FDColoring
can only be used if the number of cells is divisible
by 2*NGc+1. Even though this is only a slight
annoyance, I was wondering if you were working on
this matter / if you had a quick fix at hand? At any
rate, I think it would be nice if a warning was
displayed in the FDColoring documentation? <br>
<br>
Respectfully, <br>
Pierre Bernigaud </p>
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