<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 style>This is what debugging is about. We are not running your problem. How could this be debugged?</div><div style><br></div><div style>1) Run the problem w/o a null space so that it finishes</div>
<div style><br></div><div style>2) Look at the output for -ksp_view</div><div style><br></div><div style>3) Does the coarse solver say that it is shifted?</div><div style><br></div><div style>4) Are there options which were unused?</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">
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"><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>