Hi Barry,<br>Yes, exactly. The original multi-components system scale quite unevenly. I will try to rescale it. <br>Could this be helpful to show some promise on quadratic convergence?<br><br>Thanks a lot,<br><br>Yan <br><br>
<div class="gmail_quote">On Sun, Jan 10, 2010 at 4:35 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="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<br>
You already got a 10^16 drop in the residual norm. It is not realistic to expect to get much more than that for double precision calculations. Perhaps your original F() has some funky scaling of different components that you can fix.<br>
<font color="#888888">
<br>
<br>
<br>
Barry</font><div><div></div><div class="h5"><br>
<br>
On Jan 10, 2010, at 2:55 PM, Ryan Yan wrote:<br>
<br>
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
Hi All,<br>
I am solving a nonlinear system using snes. The -snes_monitor option has the following output:<br>
<br>
0 SNES Function norm 2.640163923729e+09<br>
1 SNES Function norm 1.047643565314e+08<br>
2 SNES Function norm 1.712732074788e+06<br>
3 SNES Function norm 1.002169173269e+04<br>
4 SNES Function norm 1.655878303433e+03<br>
5 SNES Function norm 3.746498305706e+02<br>
6 SNES Function norm 8.317435704773e+01<br>
7 SNES Function norm 1.857639969641e+01<br>
8 SNES Function norm 4.149691057773e+00<br>
9 SNES Function norm 9.265604042412e-01<br>
10 SNES Function norm 2.069527103214e-01<br>
11 SNES Function norm 4.624186491082e-02<br>
12 SNES Function norm 1.035558432688e-02<br>
13 SNES Function norm 2.341362958811e-03<br>
14 SNES Function norm 5.507445427277e-04<br>
15 SNES Function norm 1.485123568354e-04<br>
16 SNES Function norm 5.180043781814e-05<br>
17 SNES Function norm 2.341966514486e-05<br>
18 SNES Function norm 1.344936158651e-05<br>
19 SNES Function norm 1.054812641176e-05<br>
Number of Newton iterations = 19<br>
Converged reason is 4<br>
<br>
It looks like the iterate never falls into a quadratic convergence region before it converges. Is there any hint to understand this behavior?<br>
<br>
Thanks a lot,<br>
<br>
Yan<br>
<br>
<br>
</blockquote>
<br>
</div></div></blockquote></div><br>