<html dir="ltr">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<style id="owaParaStyle" type="text/css">
<!--
p
{margin-top:0;
margin-bottom:0}
p
{margin-top:0;
margin-bottom:0}
-->
P {margin-top:0;margin-bottom:0;}</style>
</head>
<body ocsi="0" fpstyle="1">
<div style="direction: ltr;font-family: Tahoma;color: #000000;font-size: 10pt;">Hi,<br>
<br>
yes, sorry, I didn't give you so many details.<br>
<br>
Suppose I've to solve this kind of linear system:<br>
<br>
| A - B^T| | x | = 0<br>
| B C | | y | = g<br>
<br>
I've three classes for the corresponding (linear) operators A, B and C; if I decide to solve using a Schur complement approach, I get:<br>
<br>
x = A^{-1} B^T y<br>
(C + B A^{-1} B^T) y = g<br>
<br>
How do I extract the inverse of the matrix A, given such an operator A (it's publicly derived from Operator < ... > and OEMSolver::PreconditionInterface) ?<br>
I mean, I already know that if I do this:<br>
<br>
B.applyTransposed (y, foo)<br>
<br>
I can calculate foo = B^T y.<br>
Is there something similar, kind of "applyInverse" to compute and store the temporary A^{-1} B^T ??<br>
<br>
Hope now it's clearer.<br>
<br>
Cheers,<br>
<div><br>
<div style="font-family:Tahoma; font-size:13px">Andrea<br>
__________________________________________________________<br>
<br>
Andrea Sacconi<br>
PhD student, Applied Mathematics<br>
AMMP Section, Department of Mathematics, Imperial College London,<br>
London SW7 2AZ, UK<br>
a.sacconi11@imperial.ac.uk<br>
</div>
</div>
<div style="font-family: Times New Roman; color: #000000; font-size: 16px">
<hr tabindex="-1">
<div style="direction: ltr;" id="divRpF80823"><font color="#000000" face="Tahoma" size="2"><b>From:</b> Dedner, Andreas [A.S.Dedner@warwick.ac.uk]<br>
<b>Sent:</b> 17 April 2012 09:56<br>
<b>To:</b> Sacconi, Andrea; dune-fem@dune-project.org<br>
<b>Subject:</b> RE: [dune-fem] Has the Schur complement approach been implemented in DUNE-FEM somewhere?<br>
</font><br>
</div>
<div></div>
<div>
<div style="direction:ltr; font-family:Tahoma; color:#000000; font-size:10pt">Hi Andrea.<br>
<br>
I do not quite know what you are refering to? Do you mean an<br>
Uzawa like algorithm for Stokes?<br>
It would help if you gave more detail on the problem youi are solving and on the<br>
method you would like to use.<br>
Best<br>
Andreas<br>
<div style="font-family:Times New Roman; color:#000000; font-size:16px">
<hr tabindex="-1">
<div id="divRpF881343" style="direction:ltr"><font color="#000000" face="Tahoma" size="2"><b>From:</b> dune-fem-bounces+a.s.dedner=warwick.ac.uk@dune-project.org [dune-fem-bounces+a.s.dedner=warwick.ac.uk@dune-project.org] on behalf of Sacconi, Andrea [a.sacconi11@imperial.ac.uk]<br>
<b>Sent:</b> Monday, April 16, 2012 5:01 PM<br>
<b>To:</b> dune-fem@dune-project.org<br>
<b>Subject:</b> [dune-fem] Has the Schur complement approach been implemented in DUNE-FEM somewhere?<br>
</font><br>
</div>
<div></div>
<div>
<div style="direction:ltr; font-family:Tahoma; color:#000000; font-size:10pt">Hi all,<br>
<br>
I need to programme the Schur complement approach, with an appropriate preconditioner, to solve the linear systems I'm dealing with.<br>
I was wondering if anybody has already implemented it, either in his own code or in the tutorials. Just not to reinvent the wheel, or to have some useful hints.<br>
<br>
Cheers,<br>
<br>
<div>Andrea<br>
<div style="font-family:Tahoma; font-size:13px">__________________________________________________________<br>
<br>
Andrea Sacconi<br>
PhD student, Applied Mathematics<br>
AMMP Section, Department of Mathematics, Imperial College London,<br>
London SW7 2AZ, UK<br>
a.sacconi11@imperial.ac.uk<br>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</body>
</html>