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<div style="direction: ltr;font-family: Tahoma;color: #000000;font-size: 10pt;">Hi.<br>
Are you starting from the dune-fem-school? If so then you can easily adapt<br>
the poisson example (witch assembles the stiffness matrix for<br>
-div Kgrad u + Mu <br>
to only contain the mass part.<br>
Best<br>
Andreas<br>
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<div style="direction: ltr;" id="divRpF317204"><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 Mauro Pagani [account.facile@hotmail.it]<br>
<b>Sent:</b> 06 November 2012 10:47<br>
<b>To:</b> dune-fem@dune-project.org<br>
<b>Subject:</b> [dune-fem] Building stiffness matrix<br>
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<div dir="ltr">Hi,<br>
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BODY {direction: ltr;font-family: Tahoma;color: #000000;font-size: 10pt;}P {margin-top:0;margin-bottom:0;}</style>I have
a problem about solving the equation<br>
<br>
<font style="font-size: 16pt;" size="4"><font size="2"><font style="font-size: 16pt;" size="4"><font style="font-size: 10pt;" size="2"><font style="font-size: 16pt;" size="4"><font style="font-size: 10pt;" size="2"><font style="font-size: 16pt;" size="4"><font style="font-size: 10pt;" size="2"><font style="font-size: 16pt;" size="4"><font style="font-size: 10pt;" size="2"><font style="font-size: 16pt;" size="4"><font style="font-size: 10pt;" size="2"><font style="font-size: 16pt;" size="4"><font style="font-size: 10pt;" size="2"><font style="font-size: 16pt;" size="4"><font style="font-size: 10pt;" size="2">________________________________________________________________________________________________________</font></font></font></font></font></font></font></font></font></font></font></font></font></font></font></font><br>
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<font style="font-size: 20pt;" size="5"><font style="font-size: 16pt;" size="4">$B&E(B</font></font><font style="font-size: 16pt;" size="4"><font style="font-size: 20pt;" size="5"><font style="font-size: 8pt;" size="1!
"><font style="font-size: 16pt;" size="4">*<font style="font-size: 20pt;" size="5"><font style="font-size: 8pt;" size="1"><font style="font-size: 16pt;" size="4">$B&E(B
</font></font></font></font></font></font>$B"_(B</font><font style="font-size: 8pt;" size="1!
">t<font style="font-size: 16pt;" size="4">v + 4v(v*v-1) - 0.5*$B&E(B*<font style="font-size: 20pt;" size="5"><font style="font-size: 8pt;" size="1"><font style="font-size: 16pt;" size="4">$B&E(B
div M</font></font></font></font></font><font style="font-size: 20pt;" size="5"><font style="font-size: 16pt;" size="4">
</font></font><img class="ecxtex" alt="\mathbf{\nabla}"><font style="font-size: 16pt;" size="4">v<font style="font-size: 10pt;" size="2"><font style="font-size: 16pt;" size="4">= 0</font></font></font><font style="font-size: 20pt;" size="5"><font style="font-size: 16pt;" size="4"><font style="font-size: 10pt;" size="2"><font style="font-size: 16pt;" size="4"><br>
</font></font></font></font><br>
________________________________________________________________________________________________________<br>
<br>
I manage to arrive to modelize this with Euler metho<font style="font-size: 10pt;" size="2">d, ! but I don't understand how to calcu<font style="font-size: 10pt;" size="2">late Sti<font style="font-size: 10pt;" size="2">ffness Matrix<br>
<font style="font-size: 10pt;" size="2"><font style="font-size: 10pt;" size="2">of the form:<br>
<br>
</font></font></font></font></font><font style="font-size: 20pt;" size="5"><font style="font-size: 8pt;" size="1!
"><font style="font-size: 16pt;" size="4"><font style="font-size: 20pt;" size="5"><font style="font-size: 8pt;" size="1"><font style="font-size: 16pt;" size="4">S<font style="font-size: 16pt;" size="4"><font style="font-size: 8pt;" size="1">ij</font>
= <font style="font-size: 16pt;" size="4">\int<font style="font-size: 8pt;" size="1">K</font></font></font></font></font></font></font></font></font>
<font style="font-size: 20pt;" size="5"><font style="font-size: 8pt;" size="1!
"><font style="font-size: 16pt;" size="4"><font style="font-size: 20pt;" size="5"><font style="font-size: 8pt;" size="1"><font style="font-size: 16pt;" size="4">((M</font></font></font></font></font></font><font style="font-size: 20pt;" size="5"><font style="font-size: 16pt;" size="4">
</font></font><img class="ecxtex" alt="\mathbf{\nabla}"><font style="font-size: 16pt;" size="4">$B&U(B<font style="font-size: 8pt;" size="1">j<font style="font-size: 16pt;" size="4">)</font></font></font><img class="ecxtex" alt="\mathbf{\nabla}"><font style="font-size: 16pt;" size="4">$B&U(B<font style="font-size: 8pt;" size="1">i<font style="font-size: 16pt;" size="4">)</font>
<font style="font-size: 16pt;" size="4">dx<br>
<font style="font-size: 10pt;" size="2"><br>
<font style="font-size: 10pt;" size="2">With K a r<font style="" size="2">ight </font>
trian<font style="font-size: 10pt;" size="2">gle (<font style="font-size: 10pt;" size="2">dimensions
<font style="font-size: 10pt;" size="2">h<font style="font-size: 10pt;" size="2"> x h) of
<font style="font-size: 10pt;" size="2">the grid</font> and M<font style="font-size: 8pt;" size="1"><font style="font-size: 10pt;" size="2">
<font style="font-size: 10pt;" size="2">the co<font style="font-size: 10pt;" size="2">efficient of anisotropy<font style="font-size: 10pt;" size="2"> (in more
<font style="font-size: 10pt;" size="2">dimensions this becom<font style="font-size: 10pt;" size="2">e a diagonal square matrix)<font style="font-size: 10pt;" size="2">.<br>
<br>
<font style="font-size: 10pt;" size="2">I k<font style="font-size: 10pt;" size="2">now that
<font style="font-size: 10pt;" size="2">S is symmetric<font style="font-size: 10pt;" size="2">, but not diagonal: so t<font style="font-size: 10pt;" size="2">o build
<font style="font-size: 10pt;">it I need to ha<font style="font-size: 10pt;" size="2">ve
<font style="font-size: 10pt;" size="2">a node and all its neighbours<font style="font-size: 10pt;" size="2">...how could I implement this?<br>
<br>
<font style="font-size: 10pt;" size="2">Thank you for you<font style="font-size: 10pt;" size="2">r help,<br>
<br>
<font style="font-size: 10pt;" size="2">Mauro P<font style="font-size: 10pt;" size="2">agani</font></font><br>
</font></font></font></font></font></font></font></font></font></font></font></font></font></font></font></font></font></font></font></font></font></font></font></font></font></font></font></font><br>
<font style="font-size: 10pt;" size="2"><font style="font-size: 10pt;" size="2"></font></font><br>
<br>
<font style="font-size: 20pt;" size="5"><font style="font-size: 8pt;" size="1!
"><font style="font-size: 16pt;" size="4"></font></font></font></div>
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