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    <font face="Ubuntu">I attached the complete output.<br>
      I used 2 processors for this run. I wanted to use only one to have
      a cleaner output but I could not because of this error:<br>
      <br>
      [0]PCSetData_AGG bs=1 MM=32768<br>
      [0]PETSC ERROR: --------------------- Error Message
      ------------------------------------<br>
      [0]PETSC ERROR: Arguments are incompatible!<br>
      [0]PETSC ERROR: MatMatMult requires A, mpiaij, to be compatible
      with B, seqaij!<br>
      [0]PETSC ERROR:
      ------------------------------------------------------------------------<br>
      [0]PETSC ERROR: Petsc Release Version 3.3.0, Patch 3, Wed Aug 29
      11:26:24 CDT 2012<br>
      [0]PETSC ERROR: See docs/changes/index.html for recent updates.<br>
      [0]PETSC ERROR: See docs/faq.html for hints about trouble
      shooting.<br>
      [0]PETSC ERROR: See docs/index.html for manual pages.<br>
      [0]PETSC ERROR:
      ------------------------------------------------------------------------<br>
      [0]PETSC ERROR: ./hit on a  named nid15343 by Unknown Wed May 29
      18:15:24 2013<br>
      [0]PETSC ERROR: Libraries linked from<br>
      [0]PETSC ERROR: Configure run at<br>
      [0]PETSC ERROR: Configure options<br>
      [0]PETSC ERROR:
      ------------------------------------------------------------------------<br>
      [0]PETSC ERROR: MatMatMult() line 8614 in
      src/mat/interface/matrix.c<br>
      [0]PETSC ERROR: PCGAMGOptprol_AGG() line 1358 in
      src/ksp/pc/impls/gamg/agg.c<br>
      [0]PETSC ERROR: PCSetUp_GAMG() line 673 in
      src/ksp/pc/impls/gamg/gamg.c<br>
      [0]PETSC ERROR: PCSetUp() line 832 in
      src/ksp/pc/interface/precon.c<br>
      [0]PETSC ERROR: KSPSetUp() line 278 in
      src/ksp/ksp/interface/itfunc.c<br>
      hit: gamg.c:568: PCSetUp_GAMG: Assertion `pc->setupcalled'
      failed.<br>
      <br>
    </font>
    <div class="moz-cite-prefix">On 05/29/2013 02:29 PM, Matthew Knepley
      wrote:<br>
    </div>
    <blockquote
cite="mid:CAMYG4GnvZpPrzKApWOs067VwRGfQYNvOYwoeQPznCnG4AqiLDg@mail.gmail.com"
      type="cite">
      <div dir="ltr">On Wed, May 29, 2013 at 5:25 PM, Michele Rosso <span
          dir="ltr"><<a moz-do-not-send="true"
            href="mailto:mrosso@uci.edu" target="_blank">mrosso@uci.edu</a>></span>
        wrote:<br>
        <div class="gmail_extra">
          <div class="gmail_quote">
            <blockquote class="gmail_quote" style="margin:0 0 0
              .8ex;border-left:1px #ccc solid;padding-left:1ex">
              <div text="#000000" bgcolor="#FFFFFF"> <font
                  face="Ubuntu">Hi,<br>
                  <br>
                  I proceeded as Matt suggested. I am running without
                  nullspace (Dirichlet's BCs) with the following
                  options:<br>
                  <br>
                  -pc_type gamg  -pc_mg_cycle_type v 
                  -pc_gamg_agg_nsmooths 1
                  -mg_coarse_sub_pc_factor_shift_type NONZERO -ksp_view
                  -options_left<br>
                  <br>
                  The results are fine and the run finishes. The output
                  of -ksp_view does not say anything about the coarse
                  solver being shifted.<br>
                  In fact the option  </font><font face="Ubuntu"><font
                    face="Ubuntu">-mg_coarse_sub_pc_factor_shift_type
                    NONZERO is not used:<br>
                  </font></font></div>
            </blockquote>
            <div><br>
            </div>
            <div style="">Please show us the COMPLETE output.</div>
            <div style=""><br>
            </div>
            <div style="">  Thanks,</div>
            <div style=""><br>
            </div>
            <div style="">     Matt</div>
            <div> </div>
            <blockquote class="gmail_quote" style="margin:0 0 0
              .8ex;border-left:1px #ccc solid;padding-left:1ex">
              <div text="#000000" bgcolor="#FFFFFF"><font face="Ubuntu"><font
                    face="Ubuntu"> #PETSc Option Table entries:<br>
                    -ksp_view<br>
                    -mg_coarse_sub_pc_factor_shift_type NONZERO<br>
                    -options_left<br>
                    -pc_gamg_agg_nsmooths 1<br>
                    -pc_mg_cycle_type v<br>
                    -pc_type gamg<br>
                    #End of PETSc Option Table entries<br>
                    There is one unused database option. It is:<br>
                    Option left:
                    name:-mg_coarse_sub_pc_factor_shift_type value:
                    NONZERO<br>
                    <br>
                    Michele<br>
                    <br>
                    <br>
                  </font></font>
                <div>On 05/24/2013 03:20 PM, Matthew Knepley wrote:<br>
                </div>
                <blockquote type="cite">
                  <div dir="ltr">On Fri, May 24, 2013 at 5:18 PM,
                    Michele Rosso <span dir="ltr"><<a
                        moz-do-not-send="true"
                        href="mailto:mrosso@uci.edu" target="_blank">mrosso@uci.edu</a>></span>
                    wrote:<br>
                    <div class="gmail_extra">
                      <div class="gmail_quote">
                        <blockquote class="gmail_quote" style="margin:0
                          0 0 .8ex;border-left:1px #ccc
                          solid;padding-left:1ex">
                          <div text="#000000" bgcolor="#FFFFFF"> <font
                              face="Ubuntu">Using <br>
                              <br>
                              -pc_type gamg -pc_mg_cycle_type v
                              -pc_gamg_agg_nsmooths 1
                              -mg_coarse_sub_pc_factor_shift_type
                              NONZERO  -option_left -ksp_view <br>
                            </font></div>
                        </blockquote>
                        <div><br>
                        </div>
                        <div>This is what debugging is about. We are not
                          running your problem. How could this be
                          debugged?</div>
                        <div><br>
                        </div>
                        <div>1) Run the problem w/o a null space so that
                          it finishes</div>
                        <div><br>
                        </div>
                        <div>2) Look at the output for -ksp_view</div>
                        <div><br>
                        </div>
                        <div>3) Does the coarse solver say that it is
                          shifted?</div>
                        <div><br>
                        </div>
                        <div>4) Are there options which were unused?</div>
                        <div><br>
                        </div>
                        <div>   Matt</div>
                        <div> </div>
                        <blockquote class="gmail_quote" style="margin:0
                          0 0 .8ex;border-left:1px #ccc
                          solid;padding-left:1ex">
                          <div text="#000000" bgcolor="#FFFFFF"><font
                              face="Ubuntu"> still produces the same
                              error:<br>
                              <br>
                              [0]PCSetData_AGG bs=1 MM=131072<br>
                              [0]PETSC ERROR: ---------------------
                              Error Message
                              ------------------------------------<br>
                              [0]PETSC ERROR: Detected zero pivot in LU
                              factorization:<br>
                              see <a moz-do-not-send="true"
                                href="http://www.mcs.anl.gov/petsc/documentation/faq.html#ZeroPivot"
                                target="_blank">http://www.mcs.anl.gov/petsc/documentation/faq.html#ZeroPivot</a>!<br>
                              [0]PETSC ERROR: Zero pivot row 280 value
                              6.56964e-17 tolerance 2.22045e-14!<br>
                              [0]PETSC ERROR:
                              ------------------------------------------------------------------------<br>
                              [0]PETSC ERROR: Petsc Release Version
                              3.3.0, Patch 3, Wed Aug 29 11:26:24 CDT
                              2012<br>
                              [0]PETSC ERROR: See
                              docs/changes/index.html for recent
                              updates.<br>
                              [0]PETSC ERROR: See docs/faq.html for
                              hints about trouble shooting.<br>
                              [0]PETSC ERROR: See docs/index.html for
                              manual pages.<br>
                              [0]PETSC ERROR:
                              ------------------------------------------------------------------------<br>
                              [0]PETSC ERROR: ./hit on a  named nid15363
                              by Unknown Fri May 24 17:06:50 2013<br>
                              [0]PETSC ERROR: Libraries linked from<br>
                              [0]PETSC ERROR: Configure run at<br>
                              [0]PETSC ERROR: Configure options<br>
                              [0]PETSC ERROR:
                              ------------------------------------------------------------------------<br>
                              [0]PETSC ERROR: MatPivotCheck_none() line
                              583 in
src/mat/impls/aij/seq//ptmp/skelly/petsc/3.3.03/cray_interlagos_build/real/src/include/petsc-private/matimpl.h<br>
                              [0]PETSC ERROR: MatPivotCheck() line 602
                              in
src/mat/impls/aij/seq//ptmp/skelly/petsc/3.3.03/cray_interlagos_build/real/src/include/petsc-private/matimpl.h<br>
                              [0]PETSC ERROR:
                              MatLUFactorNumeric_SeqAIJ() line 585 in
                              src/mat/impls/aij/seq/aijfact.c<br>
                              [0]PETSC ERROR: MatLUFactorNumeric() line
                              2803 in src/mat/interface/matrix.c<br>
                              [0]PETSC ERROR: PCSetUp_LU() line 160 in
                              src/ksp/pc/impls/factor/lu/lu.c<br>
                              [0]PETSC ERROR: PCSetUp() line 832 in
                              src/ksp/pc/interface/precon.c<br>
                              [0]PETSC ERROR: KSPSetUp() line 278 in
                              src/ksp/ksp/interface/itfunc.c<br>
                              [0]PETSC ERROR:
                              PCSetUpOnBlocks_BJacobi_Singleblock() line
                              715 in src/ksp/pc/impls/bjacobi/bjacobi.c<br>
                              [0]PETSC ERROR: PCSetUpOnBlocks() line 865
                              in src/ksp/pc/interface/precon.c<br>
                              [0]PETSC ERROR: KSPSetUpOnBlocks() line
                              154 in src/ksp/ksp/interface/itfunc.c<br>
                              [0]PETSC ERROR: KSPSolve() line 403 in
                              src/ksp/ksp/interface/itfunc.c<br>
                              [0]PETSC ERROR:
                              PCSetUpOnBlocks_BJacobi_Singleblock() line
                              715 in src/ksp/pc/impls/bjacobi/bjacobi.c<br>
                              [0]PETSC ERROR: PCSetUpOnBlocks() line 865
                              in src/ksp/pc/interface/precon.c<br>
                              [0]PETSC ERROR: KSPSetUpOnBlocks() line
                              154 in src/ksp/ksp/interface/itfunc.c<br>
                              [0]PETSC ERROR: KSPSolve() line 403 in
                              src/ksp/ksp/interface/itfunc.c<br>
                              [0]PETSC ERROR: PCMGMCycle_Private() line
                              20 in src/ksp/pc/impls/mg/mg.c<br>
                              [0]PETSC ERROR: PCMGMCycle_Private() line
                              49 in src/ksp/pc/impls/mg/mg.c<br>
                              [0]PETSC ERROR: PCMGMCycle_Private() line
                              49 in src/ksp/pc/impls/mg/mg.c<br>
                              [0]PETSC ERROR: PCMGMCycle_Private() line
                              49 in src/ksp/pc/impls/mg/mg.c<br>
                              [0]PETSC ERROR: PCApply_MG() line 326 in
                              src/ksp/pc/impls/mg/mg.c<br>
                              [0]PETSC ERROR: PCApply() line 384 in
                              src/ksp/pc/interface/precon.c<br>
                              [0]PETSC ERROR: KSPSolve_CG() line 139 in
                              src/ksp/ksp/impls/cg/cg.c<br>
                              [0]PETSC ERROR: KSPSolve() line 446 in
                              src/ksp/ksp/interface/itfunc.c<br>
                              <br>
                            </font>
                            <div>On 05/24/2013 02:51 PM, Jed Brown
                              wrote:<br>
                            </div>
                            <blockquote type="cite">
                              <pre>Michele Rosso <a moz-do-not-send="true" href="mailto:mrosso@uci.edu" target="_blank"><mrosso@uci.edu></a> writes:

</pre>
                              <blockquote type="cite">
                                <blockquote type="cite">
                                  <pre>    With petsc-3.4 (which you should upgrade to), use
    -mg_coarse_sub_pc_factor_shift_type NONZERO
</pre>
                                </blockquote>
                              </blockquote>
                              <pre>Actually, use this with petsc-3.3 also (and please upgrade to
petsc-3.4).

The option you were passing was not being used.

</pre>
                            </blockquote>
                            <br>
                          </div>
                        </blockquote>
                      </div>
                      <br>
                      <br clear="all">
                      <span class="HOEnZb"><font color="#888888">
                          <div><br>
                          </div>
                          -- <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 </font></span></div>
                  </div>
                </blockquote>
                <br>
              </div>
            </blockquote>
          </div>
          <br>
          <br clear="all">
          <div><br>
          </div>
          -- <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
        </div>
      </div>
    </blockquote>
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