<div dir="ltr">On Wed, May 29, 2013 at 5:25 PM, Michele Rosso <span dir="ltr"><<a 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 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 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 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>