Thanks, I monitored the ksp but I found that " unpreconditioned resid norm" and "true resid norm" are exactly the same. I can't understand while I set Jacobian = Precondition matrix ?!!!<br><br>In addition, I am solving true Newton iterations and I saw that first iteration is good (as I got from previous linear solvers) and the norm of the matrix is what I expected BUT for the next nonlinear iteration, the linear iterations can not converge to desired tolerance!!!<br>
<br><br><div class="gmail_quote">On Tue, Oct 11, 2011 at 6:18 PM, Barry Smith <span dir="ltr"><<a href="mailto:bsmith@mcs.anl.gov">bsmith@mcs.anl.gov</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
<br>
<a href="http://www.mcs.anl.gov/petsc/petsc-as/documentation/faq.html#kspdiverged" target="_blank">http://www.mcs.anl.gov/petsc/petsc-as/documentation/faq.html#kspdiverged</a><br>
<div><div></div><div class="h5"><br>
<br>
On Oct 11, 2011, at 9:45 AM, behzad baghapour wrote:<br>
<br>
> Dear all,<br>
><br>
> I set my Jacobian matrix in petsc and test it to ensure for correctness for Jacobian and RHS function. ( also precondition = jacobian )<br>
> I have solved my problem before with some other solvers (gmers/ILU(2)) and the convergence has been achieved within 15 - 16 iterations.<br>
><br>
> But in petsc the linear solver (ksp=GMRES) is not converged within this number ( or may be converged in more than 700 iterations!!! ). I know that I should have a mistake but I can't predict it?<br>
><br>
> Please help me what parts of petsc solver I should check?<br>
><br>
> Regards,<br>
> Behzad<br>
><br>
> --<br>
> ==================================<br>
> Behzad Baghapour<br>
> Ph.D. Candidate, Mechecanical Engineering<br>
> University of Tehran, Tehran, Iran<br>
> <a href="https://sites.google.com/site/behzadbaghapour" target="_blank">https://sites.google.com/site/behzadbaghapour</a><br>
> Fax: 0098-21-88020741<br>
> ==================================<br>
><br>
<br>
</div></div></blockquote></div><br><br clear="all"><br>-- <br>==================================<br>Behzad Baghapour<br>Ph.D. Candidate, Mechecanical Engineering<br>University of Tehran, Tehran, Iran<br><a href="https://sites.google.com/site/behzadbaghapour" target="_blank">https://sites.google.com/site/behzadbaghapour</a><br>
Fax: 0098-21-88020741<br>==================================<br><br>