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Hi Jed,<br>
<br>
Ok thanks. Btw, is it better to solve my x/y eqns together? How can
I do that?<br>
<br>
Is there any examples which I can follow?<br>
<pre class="moz-signature" cols="72">Yours sincerely,
TAY wee-beng</pre>
<br>
On 10/7/2011 12:51 AM, Jed Brown wrote:
<blockquote
cite="mid:CAM9tzSn2JC4LEAGOKiDAN=rfh0yD+2M9wORn9yW84=VAtKZasQ@mail.gmail.com"
type="cite">
<div class="gmail_quote">On Sat, Jul 9, 2011 at 17:43, TAY
wee-beng <span dir="ltr"><<a moz-do-not-send="true"
href="mailto:zonexo@gmail.com">zonexo@gmail.com</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt
0.8ex; border-left: 1px solid rgb(204, 204, 204);
padding-left: 1ex;">
<div bgcolor="#ffffff" text="#000000">Sorry about that. I just
run interactively to get the output.<br>
<br>
Now I issued :<br>
<br>
mpiexec -np 1 ./a.out -ksp_type gmres -ksp_gmres_restart
1000 -ksp_gmres_modifiedgramschmidt
-ksp_monitor_true_residual -ksp_view -pc_type asm
-sub_pc_type lu > log1</div>
</blockquote>
</div>
<br>
<div>Your matrix is singular which implies a bug in your assembly
code, probably in the way you impose boundary conditions. Switch
to a very small problem size (e.g. 4 cells) and debug it until
the matrix is correct and non-singular.</div>
<div><br>
</div>
<div>You should also check the error codes so the code doesn't try
to keep going after a fatal error.</div>
</blockquote>
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