<html><head><meta http-equiv="Content-Type" content="text/html charset=windows-1252"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">You need an updated PETSc. (I thought 3.2 had an early version of gamg … but you need 3.3 or dev)<div><br></div><div>Mark</div><div><br><div><div>On Oct 29, 2012, at 8:49 AM, w_ang_temp <<a href="mailto:w_ang_temp@163.com">w_ang_temp@163.com</a>> wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div style="line-height: 1.7; font-size: 14px; font-family: arial; "><div>Hello, Jed</div>
<div> I use the command:</div>
<div> mpiexec -n 4 ./ex4f -ksp_type cgs -pc_type gamg -pc_gamg_agg_nsmooths 1 -ksp_rtol 1.0e-15 -ksp_converged_reason</div>
<div> The error is as follows:<br>[0]PETSC ERROR: --------------------- Error Message ------------------------------------<br>[0]PETSC ERROR: Unknown type. Check for miss-spelling or missing external package needed for type<br> <a href="seehttp://www.mcs.anl.gov/petsc/petsc-as/documentation/installation.html#external!">seehttp://www.mcs.anl.gov/petsc/petsc-as/documentation/installation.html#external!</a><br>[0]PETSC ERROR: Unable to find requested PC type gamg!<br>[0]PETSC ERROR: ------------------------------------------------------------------------<br>[0]PETSC ERROR: Petsc Release Version 3.2.0, Patch 7, Thu Mar 15 09:30:51 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: ./ex4f on a arch-linu named ubuntu by geo Mon Oct 29 05:40:13 2012<br>[0]PETSC ERROR: Libraries linked from /home
/geo/soft/petsc/petsc-3.2-p7/arch-linux2-c-opt/lib<br>[0]PETSC ERROR: Configure run at Mon Jul 2 20:33:17 2012<br>[0]PETSC ERROR: Configure options --with-mpi-dir=/home/geo/soft/mpich2 --download-f-blas-lapack=1 --with-x=1 --with-debugging=0 --download-parmetis --download-mumps --download-scalapack --download-blacs<br>[0]PETSC ERROR: ------------------------------------------------------------------------<br>[0]PETSC ERROR: PCSetType() line 67 in src/ksp/pc/interface/pcset.c<br>[0]PETSC ERROR: PCSetFromOptions() line 184 in src/ksp/pc/interface/pcset.c<br>[0]PETSC ERROR: KSPSetFromOptions() line 286 in src/ksp/ksp/interface/itcl.c</div>
<div> When I use 'mpiexec -n 4 ./ex4f -ksp_type cgs -pc_type sor -ksp_rtol 1.0e-15 -ksp_converged_reason', it is ok. So</div>
<div>what is the possible reason?</div>
<div> Thanks.</div>
<div> Jim<br><br><br><br><br></div>
<div></div>
<div id="divNeteaseMailCard"></div>
<div><br></div>At 2012-10-28 22:25:31,"Jed Brown" <<a href="mailto:jedbrown@mcs.anl.gov">jedbrown@mcs.anl.gov</a>> wrote:<br>
<blockquote style="BORDER-LEFT: #ccc 1px solid; MARGIN: 0px 0px 0px 0.8ex; PADDING-LEFT: 1ex" id="isReplyContent"><p>Try the simple option I just sent.</p>
<div class="gmail_quote">On Oct 28, 2012 6:38 AM, "w_ang_temp" <<a href="mailto:w_ang_temp@163.com">w_ang_temp@163.com</a>> wrote:<br type="attribution">
<blockquote style="BORDER-LEFT: #ccc 1px solid; MARGIN: 0px 0px 0px 0.8ex; PADDING-LEFT: 1ex" class="gmail_quote">
<div style="LINE-HEIGHT: 1.7; FONT-FAMILY: arial; FONT-SIZE: 14px">
<div>Hello, Jed</div>
<div> Thanks for your timely reply. I deal with the soil-water coupled problem in geotechnical engineering, </div>
<div>whose stiffness matrix is ill-conditioned. I have did some work about it, mainly finding the effective</div>
<div>solvers and preconditioners. I used the command line option like this:</div>
<div>mpiexec -n 4 ./ex4f -ksp_type cgs -pc_type sor -ksp_rtol 1.0e-15 -ksp_converged_reason.</div>
<div> So, I also want to use the multigrid just like the simple command. There is only a little introduction</div>
<div>about multigrid in the manual. Multigrid is complex and not a easy thing for me, so I just need to konw how</div>
<div>to use it simply in PETSc to solve the Ax=b system.</div>
<div> Thanks.</div>
<div> Jim<br><br><br><br><br></div>
<div></div>
<div></div>
<div><br></div>>At 2012-10-28 21:17:00,"Jed Brown" <<a href="mailto:jedbrown@mcs.anl.gov" target="_blank">jedbrown@mcs.anl.gov</a>> wrote:<br>
<blockquote style="BORDER-LEFT: #ccc 1px solid; MARGIN: 0px 0px 0px 0.8ex; PADDING-LEFT: 1ex"><p>>Algebraic multigrid can be used directly, -pc_type gamg -pc_gamg_agg_nsmooths 1. Geometric either required that you use the PCMG interface to set >interpolation (and provide a coarse operator for non-Galerkin) or use a DM that provides coarsening capability.</p><p>>What kind of problem are you solving?</p>
<div class="gmail_quote">>>On Oct 28, 2012 6:09 AM, "w_ang_temp" <<a href="mailto:w_ang_temp@163.com" target="_blank">w_ang_temp@163.com</a>> wrote:<br type="attribution">
<blockquote style="BORDER-LEFT: #ccc 1px solid; MARGIN: 0px 0px 0px 0.8ex; PADDING-LEFT: 1ex" class="gmail_quote">
<div style="LINE-HEIGHT: 1.7; FONT-FAMILY: arial; FONT-SIZE: 14px">
<div>>>Hello,</div>
<div>>> I want to use the multigrid as a preconditioner. The introduction about it in the manual is little.</div>
<div>>>So are there some typical examples or details about multigrid? Is it used just like other preconditioners</div>
<div>>>like jacobi, sor, which can be simply used in the cammand line options?</div>
<div>>> Thanks.</div>
<div>>> Jim</div></div><br><br><span title="neteasefooter"><span></span></span></blockquote></div></blockquote></div><br><br><span title="neteasefooter"><span></span></span></blockquote></div></blockquote></div><br><br><span title="neteasefooter"><span id="netease_mail_footer"></span></span></blockquote></div><br></div></body></html>