<span style="font-size:10pt;"><p style="font-size:12pt;margin-top:0;margin-bottom:0;"><span style="font-size:10pt;">Thank you. I will try this. This feels what i want. </span></p>
<p style="font-size:12pt;margin-top:0;margin-bottom:0;"><span style="font-size:10pt;">Abdul<br><br>------ Original Message ------<br><b>From: </b>Matthew Knepley <knepley@gmail.com><br><b>Date: </b>26/10/2012 19:13<br><b>To: </b>Abdul Hanan Sheikh;PETSc users list;<br><b>Subject: </b>Re: [petsc-users] Two PCs on same residual in multiplicative fashion !<br><br>On Fri, Oct 26, 2012 at 1:05 PM, Abdul Hanan Sheikh <span dir="ltr"><<a href="mailto:hanangul12@yahoo.co.uk" target="_blank">hanangul12@yahoo..co.uk</a>></span> wrote:<br></span></p>
<knepley@gmail.com><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div><div style="font-size:10pt;font-family:verdana,helvetica,sans-serif"><div><span><br></span></div><div style="font-style:normal;font-size:13.3333px;background-color:transparent;font-family:verdana,helvetica,sans-serif">
<span>Yes, it sounds crazy when we look exclusively at this. But I do not do this exclusively. <br></span></div><div style="font-style:normal;font-size:13.3333px;background-color:transparent;font-family:verdana,helvetica,sans-serif">
<span>Basically, this happening [ </span>P1^{-1} P2^{-1} A x = P1^{-1} P2^{-1} b ] occurs as a part of my two-level solver. <br></div><div style="font-style:normal;font-size:13.3333px;background-color:transparent;font-family:verdana,helvetica,sans-serif">
Any how I have to do this. <br></div><div style="font-style:normal;font-size:13.3333px;background-color:transparent;font-family:verdana,helvetica,sans-serif"><br></div><div style="font-style:normal;font-size:13.3333px;background-color:transparent;font-family:verdana,helvetica,sans-serif">
I had a realization, PCCOMPOSITE does not do exactly what I want. I read about PCCOMPOSITE in manual. :( </div></div></div></blockquote><div><br></div><div>Just use PCSHELL, and in the PCApply() function do two KSPSolve()s, one with each matrix.</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><div style="font-size:10pt;font-family:verdana,helvetica,sans-serif">
<div style="font-style:normal;font-size:13.3333px;background-color:transparent;font-family:verdana,helvetica,sans-serif">Thanks, <br></div><div style="font-style:normal;font-size:13.3333px;background-color:transparent;font-family:verdana,helvetica,sans-serif">
Abdul <br></div><br><div><span style="color:rgb(0,0,255)"><span style="font-family:verdana,helvetica,sans-serif"><span style="font-family:lucida console,sans-serif"></span></span></span><span style="color:rgb(0,0,255)"><span style="font-family:verdana,helvetica,sans-serif"></span></span> </div>
<div><br><blockquote style="border-left:2px solid rgb(16,16,255);margin-left:5px;margin-top:5px;padding-left:5px"> <div style="font-family:verdana,helvetica,sans-serif;font-size:10pt"> <div style="font-family:times new roman,new york,times,serif;font-size:12pt">
<div dir="ltr"> <font face="Arial"> <hr size="1"> <b><span style="font-weight:bold">From:</span></b> Matthew Knepley <<a href="mailto:knepley@gmail.com" target="_blank">knepley@gmail.com</a>><br> <b><span style="font-weight:bold">To:</span></b> Abdul Hanan Sheikh <<a href="mailto:hanangul12@yahoo.co.uk" target="_blank">hanangul12@yahoo.co.uk</a>>; PETSc users list <<a href="mailto:petsc-users@mcs.anl.gov" target="_blank">petsc-users@mcs.anl.gov</a>> <br>
<b><span style="font-weight:bold">Sent:</span></b> Friday, 26 October 2012, 18:56<br> <b><span style="font-weight:bold">Subject:</span></b> Re: [petsc-users] Two PCs on same residual in multiplicative fashion !<br> </font> </div> <br><div>On Fri, Oct 26, 2012 at 12:45 PM, Abdul Hanan Sheikh <span dir="ltr"><<a rel="nofollow" href="mailto:hanangul12@yahoo.co.uk" target="_blank">hanangul12@yahoo.co.uk</a>></span> wrote:<br>
<div><blockquote style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div><div style="font-size:10pt;font-family:verdana,helvetica,sans-serif"><div><span>Thank you Matt, your assumption is alright. It was typo. </span></div><br><div><span><span style="font-family:verdana,helvetica,sans-serif"><span style="font-family:lucida console,sans-serif"></span></span></span><span style="font-family:verdana,helvetica,sans-serif"></span> </div>
<div style="font-style:normal;font-size:13.3333px;background-color:transparent;font-family:lucida console,sans-serif"><span><span style="font-family:verdana,helvetica,sans-serif">I got this idea , yet if I want to invert P2 exactly by PCLU then how should I do ?? </span></span></div>
</div></div></blockquote><div><br></div><div>Read this: <a rel="nofollow" href="http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/PC/PCKSP.html" target="_blank">http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/PC/PCKSP.html</a></div>
<div><br></div><div>This makes things more complicated. You can use PCOMPOSITE with multiplicative, but its not</div><div>exactly what you have written. This is never used because its not really effective, and doesn't make</div>
<div>much sense from a theory perspective. Are you sure you want to do this?</div><div><br></div><div> Matt</div><div><br></div><blockquote style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div><div style="font-size:10pt;font-family:verdana,helvetica,sans-serif"><div style="font-style:normal;font-size:13.3333px;background-color:transparent;font-family:verdana,helvetica,sans-serif"><span></span> </div><div style="font-style:normal;font-size:13.3333px;background-color:transparent;font-family:verdana,helvetica,sans-serif">
<span>This is indeed, but I avoid to merge(matrix product) for some reasons.. </span><br>
<span></span></div><div style="font-style:normal;font-size:13.3333px;background-color:transparent;font-family:verdana,helvetica,sans-serif"><span><br></span></div><div style="font-style:normal;font-size:13.3333px;background-color:transparent;font-family:verdana,helvetica,sans-serif">
<span>Thanks again. <br></span></div><div style="font-style:normal;font-size:13.3333px;background-color:transparent;font-family:verdana,helvetica,sans-serif"><span>Abdul<br></span></div><div style="font-style:normal;font-size:13.3333px;background-color:transparent;font-family:lucida console,sans-serif">
<span style="font-weight:bold"><br></span><blockquote style="border-left:2px solid rgb(16,16,255);margin-left:5px;margin-top:5px;padding-left:5px"> <div style="font-family:verdana,helvetica,sans-serif;font-size:10pt"> <div style="font-family:times new roman,new york,times,serif;font-size:12pt">
<div dir="ltr"> <font face="Arial"> <hr size="1"> <b><span style="font-weight:bold">From:</span></b> Matthew Knepley <<a rel="nofollow" href="mailto:knepley@gmail.com" target="_blank">knepley@gmail.com</a>><br> <b><span style="font-weight:bold">To:</span></b> Abdul Hanan Sheikh <<a rel="nofollow" href="mailto:hanangul12@yahoo.co.uk" target="_blank">hanangul12@yahoo.co.uk</a>>; PETSc users list <<a rel="nofollow" href="mailto:petsc-users@mcs.anl.gov" target="_blank">petsc-users@mcs.anl.gov</a>> <br>
<b><span style="font-weight:bold">Sent:</span></b> Friday, 26 October 2012, 18:22<br> <b><span style="font-weight:bold">Subject:</span></b> Re: [petsc-users] Two PCs on same residual in multiplicative fashion !<br> </font> </div>
<br><div>On Fri, Oct 26, 2012 at 12:04 PM, Abdul Hanan Sheikh <span dir="ltr"><<a rel="nofollow" href="mailto:hanangul12@yahoo.co.uk" target="_blank">hanangul12@yahoo.co.uk</a>></span> wrote:<br><div><blockquote style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div><div style="font-size:10pt;font-family:verdana,helvetica,sans-serif"><div><span><br></span></div><div><span>Dear Developers and members, <br></span></div><div style="font-style:normal;font-size:13.3333px;background-color:transparent;font-family:verdana,helvetica,sans-serif">
<br><span></span></div><div style="font-style:normal;font-size:13.3333px;background-color:transparent;font-family:verdana,helvetica,sans-serif"><span>I intend to solve system Ax=b with two preconditioners as follows: <br>
</span></div><div style="font-style:normal;font-size:13.3333px;background-color:transparent;font-family:verdana,helvetica,sans-serif"><br><span></span></div><div style="font-style:normal;font-size:13.3333px;background-color:transparent;font-family:verdana,helvetica,sans-serif">
<span>P1^{-1} P2^{-1} A x = P^{-1} P^{-1} b</span></div></div></div></blockquote><div><br></div><div>I assume you mean P1^{-1} P2^{-1} A x = P1^{-1} P2^{-1} b</div><div><br><span style="font-weight:bold"></span><br><br></div><div>With this setup, I think its easiest to use PCKSP with the matrix for</div>
<div>the KSP being P2. That would give you</div><div><br></div><div> P2^{-1} A x = P2^{-1} b</div><div><br></div><div>Now you can precondition that solve with another PCKSP with the matrix</div><div>for that KSP being P1, and get what you want.</div>
<div><span style="font-weight:bold"></span><br></div><div>This seems like a strange thing since you could just merge those matrices.<span style="font-weight:bold"></span><br><br></div><div> Matt</div><div> </div><blockquote style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div><div style="font-size:10pt;font-family:verdana,helvetica,sans-serif"><div style="font-style:normal;font-size:13.3333px;background-color:transparent;font-family:verdana,helvetica,sans-serif"><span></span> </div><div style="font-style:normal;font-size:13.3333px;background-color:transparent;font-family:verdana,helvetica,sans-serif">
<span>where P1 and P2 are exclusively available as matrices. <br></span></div><div style="font-style:normal;font-size:13.3333px;background-color:transparent;font-family:verdana,helvetica,sans-serif"><span>This might be crazy to many. <br>
</span></div><div style="font-style:normal;font-size:13.3333px;background-color:transparent;font-family:verdana,helvetica,sans-serif"><br><span></span></div><div style="font-style:normal;font-size:13.3333px;background-color:transparent;font-family:verdana,helvetica,sans-serif">
<span>I thought to start with PCCOMPOSITE but i do not think it does exactly what I intend. </span></div><div style="font-style:normal;font-size:13.3333px;background-color:transparent;font-family:verdana,helvetica,sans-serif"><br>
<span></span></div><div style="font-style:normal;font-size:13.3333px;background-color:transparent;font-family:verdana,helvetica,sans-serif"><span>Any Idea would be appreciated. <br></span></div><div style="font-style:normal;font-size:13.3333px;background-color:transparent;font-family:verdana,helvetica,sans-serif">
<br><span></span></div><div style="font-style:normal;font-size:13.3333px;background-color:transparent;font-family:verdana,helvetica,sans-serif"><span>A beginner!!! <br></span></div><span><div style="font-style:normal;font-size:13.3333px;background-color:transparent;font-family:verdana,helvetica,sans-serif">
<span>Abdul<br></span></div><div style="font-style:normal;font-size:13.3333px;background-color:transparent;font-family:verdana,helvetica,sans-serif"><span></span> </div><div><span style="font-family:verdana,helvetica,sans-serif"><span style="font-family:lucida console,sans-serif"></span></span><span style="font-family:verdana,helvetica,sans-serif"></span> </div>
</span></div></div></blockquote></div><br><br clear="all"><span class="HOEnZb"><font color="#888888"><span><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<br>
</font></span></font></span></div><span class="HOEnZb"><font color="#888888"><span><font color="#888888"><br></font></span></font></span></div></div></blockquote></div></div></div></blockquote><span class="HOEnZb"><font color="#888888"><div>
<br></div><div> </div></font></span></div><span class="HOEnZb"><font color="#888888"><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<br>
</font></span></div><span class="HOEnZb"><font color="#888888"><br><br> </font></span></div> </div> </blockquote></div> </div></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<br>
</span>