On Wed, Apr 8, 2009 at 5:08 PM, Yixun Liu <span dir="ltr"><<a href="mailto:enjoywm@cs.wm.edu">enjoywm@cs.wm.edu</a>></span> wrote:<br><div class="gmail_quote"><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
Hi,<br>
I build a finite element system and the related PETSc codes are following,<br>
<br>
KSPSetOperators(ksp,sparseMechanicalStiffnessMatrix,sparseMechanicalStiffnessMatrix,DIFFERENT_NONZERO_PATTERN);<br>
KSPSetTolerances(ksp,0.001,1.e-50,PETSC_DEFAULT, PETSC_DEFAULT);<br>
<br>
I output the solution and find its magnitude is about 1.0e+10. It's<br>
definitely wrong. The correct solution should be around 1 or 2. It<br>
seems the solver cannot converge. How do deal with this issue?</blockquote><div><br>Always start with LU to make sure your system is constructed correctly:<br><br> -ksp_type preonly -pc_type lu<br><br> Matt<br> </div>
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"><br>
Thanks.<br>
<font color="#888888"><br>
Yixun<br>
</font></blockquote></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>