<html aria-label="message body"><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body style="overflow-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;"><div><br></div> I believe the error checking is in place due to how to manage the extreme ghost corners of a rectangular (or box) region. Consider the grid with values as indicated<div><br></div><div><br></div><div> 1 2 3 4 5<br id="lineBreakAtBeginningOfMessage"><div> 6 7 8 9 10</div><div><br></div><div>that we mirror in both directions with</div><div><br></div><div> x 6 7 8 9 10 y</div><div> 2 1 2 3 4 5 4</div><div> 7 6 7 8 9 10 9</div><div> z 1 2 3 4 5 w</div><div><br></div><div>I think it is likely I did not want to think about this case when I wrote the code hence put the error checking in.</div><div><br></div><div>Quickly looking now it seems the mirroring is well defined so it is possible the error checking is not needed so long as the code properly handles those points. Sadly the code to set up all the communication patterns is complicated and my short-term memory was too small to be able to think about the box code. </div><div><br></div><div>The code is in src/dm/impls/da/da2.c I hope you have more stamina than I do and can take a look at it and see if it needs changes etc.</div><div><br></div><div>Note that if you install PETSc not using a —prefix configure options you can change the code and just run make libs in a PETSc directory with PETSC_DIR (and PETSC_ARCH) set and it will update the library so you first turn off the error check and see what happens.</div><div><br></div><div>If you can get it to work please let us know, it would be nice to support this case. Good luck</div><div><br></div><div><br></div><div> Barry</div><div><br></div><div><br></div><div>]<br><blockquote type="cite"><div>On Feb 19, 2026, at 9:08 PM, Macneice, Peter J. (GSFC-6740) via petsc-users <petsc-users@mcs.anl.gov> wrote:</div><br class="Apple-interchange-newline"><div>
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</span></div><div style="direction: ltr; line-height: normal; margin: 0px;"><span style="font-family: Menlo; font-size: 15px; background-color: rgb(255, 255, 255);">From my searching of the documentation, it looks to me as though this combination should
work.</span></div><div style="direction: ltr; line-height: normal; margin: 0px;"><span style="font-family: Menlo; font-size: 15px; background-color: rgb(255, 255, 255);">However for my modified version of the ex66.c tutorial code, I get the error message below.</span></div><div style="direction: ltr; line-height: normal; margin: 0px;"><span style="font-family: Menlo; font-size: 15px; background-color: rgb(255, 255, 255);"><br>
</span></div><div style="direction: ltr; line-height: normal; margin: 0px;"><span style="font-family: Menlo; font-size: 15px; background-color: rgb(255, 255, 255);">Is this really not yet supported?</span></div><div style="direction: ltr; line-height: normal; margin: 0px;"><span style="font-family: Menlo; font-size: 15px; background-color: rgb(29, 226, 223);"><br>
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</span></div><div style="direction: ltr; line-height: normal; margin: 0px;"><span style="font-family: Menlo; font-size: 15px;">Regards</span></div><div style="direction: ltr; line-height: normal; margin: 0px;"><span style="font-family: Menlo; font-size: 15px;"><br>
</span></div><div style="direction: ltr; line-height: normal; margin: 0px;"><span style="font-family: Menlo; font-size: 15px;">Peter MacNeice</span></div><div style="direction: ltr; line-height: normal; margin: 0px;"><span style="font-family: Menlo; font-size: 15px; background-color: rgb(29, 226, 223);"><br>
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</span></div><div style="direction: ltr; line-height: normal; margin: 0px;"><span style="font-family: Menlo; font-size: 15px; background-color: rgb(29, 226, 223);">[</span><span style="font-family: Menlo; font-size: 15px;">0</span><span style="font-family: Menlo; font-size: 15px; background-color: rgb(29, 226, 223);">]</span><span style="font-family: Menlo; font-size: 15px;">PETSC
ERROR: --------------------- Error Message --------------------------------------------------------------</span></div><div style="line-height: normal; margin: 0px;"><span style="font-family: Menlo; font-size: 15px;">[0]PETSC ERROR: No support for this operation for this object type</span></div><div style="line-height: normal; margin: 0px;"><span style="font-family: Menlo; font-size: 15px;">[0]PETSC ERROR: Mirror boundary and box stencil</span></div><div style="line-height: normal; margin: 0px;"><span style="font-family: Menlo; font-size: 15px;">[0]PETSC ERROR: WARNING! There are unused option(s) set! Could be the program crashed before usage or a spelling mistake, etc!</span></div><div style="line-height: normal; margin: 0px;"><span style="font-family: Menlo; font-size: 15px;">[0]PETSC ERROR: Option left: name:-dm_view (no value) source: command line</span></div><div style="line-height: normal; margin: 0px;"><span style="font-family: Menlo; font-size: 15px;">[0]PETSC ERROR: Option left: name:-ksp_monitor (no value) source: command line</span></div><div style="line-height: normal; margin: 0px;"><span style="font-family: Menlo; font-size: 15px;">[0]PETSC ERROR: See <a href="https://urldefense.us/v3/__https://petsc.org/release/faq/__;!!G_uCfscf7eWS!boqIOhIgncdTr1z60slIrCjusZEY0_bk-qkGbrlrmiepTiBAvCwW8s9c1IQ6vyT4fOeshVO3Bsu1F5HuERiBGRsq1r2LJ1zBtrM$">https://petsc.org/release/faq/</a> for trouble shooting.</span></div><div style="line-height: normal; margin: 0px;"><span style="font-family: Menlo; font-size: 15px;">[0]PETSC ERROR: PETSc Release Version 3.24.3, Jan 01, 2026</span></div><div style="line-height: normal; margin: 0px;"><span style="font-family: Menlo; font-size: 15px;">[0]PETSC ERROR: ex66_9pt with 1 MPI process(es) and PETSC_ARCH arch-darwin-c-debug on gs67-5186361 by pmacneic Thu Feb 19 21:03:16 2026</span></div><div style="line-height: normal; margin: 0px;"><span style="font-family: Menlo; font-size: 15px;">[0]PETSC ERROR: Configure options: --with-mpi-dir=/Users/pmacneic/mpich-install-3.3-gcc15 --force</span></div><div style="line-height: normal; margin: 0px;"><span style="font-family: Menlo; font-size: 15px;">[0]PETSC ERROR: #1 DMSetUp_DA_2D() at /Users/pmacneic/petsc-3.24.3/src/dm/impls/da/da2.c:212</span></div><div style="line-height: normal; margin: 0px;"><span style="font-family: Menlo; font-size: 15px;">[0]PETSC ERROR: #2 DMSetUp_DA() at /Users/pmacneic/petsc-3.24.3/src/dm/impls/da/dareg.c:17</span></div><div style="line-height: normal; margin: 0px;"><span style="font-family: Menlo; font-size: 15px;">[0]PETSC ERROR: #3 DMSetUp() at /Users/pmacneic/petsc-3.24.3/src/dm/interface/dm.c:807</span></div><div style="line-height: normal; margin: 0px;"><span style="font-family: Menlo; font-size: 15px;">[0]PETSC ERROR: #4 main() at ex66_9pt.c:77</span></div><div style="line-height: normal; margin: 0px;"><span style="font-family: Menlo; font-size: 15px;">[0]PETSC ERROR: PETSc Option Table entries:</span></div><div style="line-height: normal; margin: 0px;"><span style="font-family: Menlo; font-size: 15px;">[0]PETSC ERROR: -dm_view (source: command line)</span></div><div style="line-height: normal; margin: 0px;"><span style="font-family: Menlo; font-size: 15px;">[0]PETSC ERROR: -ksp_monitor (source: command line)</span></div><div style="line-height: normal; margin: 0px;"><span style="font-family: Menlo; font-size: 15px;">[0]PETSC ERROR: ----------------End of Error Message -------send entire error message to petsc-maint@mcs.anl.gov----------</span></div><div style="line-height: normal; margin: 0px;"><span style="font-family: Menlo; font-size: 15px;">application called MPI_Abort(MPI_COMM_SELF, 56) - process 0</span></div>
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<div id="ms-outlook-mobile-signature"><p class="MsoNormal"><span style="font-family: calibri, sans-serif; font-size: 11pt;">Macneice, Peter J. (GSFC-6740)</span><span style="font-family: calibri, sans-serif;">
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