<html><head><meta http-equiv="Content-Type" content="text/html charset=us-ascii"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><br><div><div>On Nov 9, 2012, at 10:05 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>
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<div> Sorry again for the interruption.<br> <br> As you said, if I want to use Algebraic multigrid, I can just use '-pc_type gamg<br>-pc_gamg_agg_nsmooths 1' in the command line. I think there are many other -pc_gamg_XXX<br>parameters. How can I find all the -pc_gamg_XXX? <br></div></div></blockquote><div><br></div><div>-help</div><br><blockquote type="cite"><div style="line-height: 1.7; font-size: 14px; font-family: arial; "><div> <br> Besides, I want to know more about AMG. Are there any details from PETSc, like manual,<br>documentaion, FAQ, etc?</div></div></blockquote><div><br></div><div>I would recommend the book "Multigrid" by Trottenberg, et al, and the classic "Multigrid Tutorial" is good to look at also.</div><br><blockquote type="cite"><div style="line-height: 1.7; font-size: 14px; font-family: arial; ">
<div> Also, from the above post, I want to know that if AMG can not be used in 3.2 by command<br>line option, because now I have to use 3.3 for using AMG. I just donot want to change my<br>version 3.2 now.<br></div></div></blockquote><div><br></div><div>You can use 3.2 if you like (free country) but this code was developed a lot between 3.2 and 3.3. I forget what was in 3.2 exactly. If you have a straight forward problem and 3.2 works then its is probably OK for your current purposes.</div><br><blockquote type="cite"><div style="line-height: 1.7; font-size: 14px; font-family: arial; "><div> <br> I am major in Civil Engineering and not good at math and programming. So please<br>forgive my weakness.</div>
<div> Thanks.<br> Jim <br> <br><br><br><br><br></div>
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<div><br></div>>At 2012-10-28 21:17:00,"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>>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">w_ang_temp@163.com</a>> wrote:<br type="attribution">
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<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 id="netease_mail_footer"></span></span></blockquote></div><br></body></html>