It is possible for the radius of quadratic convergence to be very small. However, I<br>would check your Jacobian, and maybe try -snes_mf.<br><br> Matt<br><br><div class="gmail_quote">On Sun, Jan 10, 2010 at 2:55 PM, Ryan Yan <span dir="ltr"><<a href="mailto:vyan2000@gmail.com">vyan2000@gmail.com</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;">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><font color="#888888"><br>Yan<br><br><br>
</font></blockquote></div><br><br clear="all"><br>-- <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>