[petsc-users] Snes behavior
Matthew Knepley
knepley at gmail.com
Sun Jan 10 14:59:07 CST 2010
It is possible for the radius of quadratic convergence to be very small.
However, I
would check your Jacobian, and maybe try -snes_mf.
Matt
On Sun, Jan 10, 2010 at 2:55 PM, Ryan Yan <vyan2000 at gmail.com> wrote:
> Hi All,
> I am solving a nonlinear system using snes. The -snes_monitor option has
> the following output:
>
> 0 SNES Function norm 2.640163923729e+09
> 1 SNES Function norm 1.047643565314e+08
> 2 SNES Function norm 1.712732074788e+06
> 3 SNES Function norm 1.002169173269e+04
> 4 SNES Function norm 1.655878303433e+03
> 5 SNES Function norm 3.746498305706e+02
> 6 SNES Function norm 8.317435704773e+01
> 7 SNES Function norm 1.857639969641e+01
> 8 SNES Function norm 4.149691057773e+00
> 9 SNES Function norm 9.265604042412e-01
> 10 SNES Function norm 2.069527103214e-01
> 11 SNES Function norm 4.624186491082e-02
> 12 SNES Function norm 1.035558432688e-02
> 13 SNES Function norm 2.341362958811e-03
> 14 SNES Function norm 5.507445427277e-04
> 15 SNES Function norm 1.485123568354e-04
> 16 SNES Function norm 5.180043781814e-05
> 17 SNES Function norm 2.341966514486e-05
> 18 SNES Function norm 1.344936158651e-05
> 19 SNES Function norm 1.054812641176e-05
> Number of Newton iterations = 19
> Converged reason is 4
>
> It looks like the iterate never falls into a quadratic convergence region
> before it converges. Is there any hint to understand this behavior?
>
> Thanks a lot,
>
> Yan
>
>
>
--
What most experimenters take for granted before they begin their experiments
is infinitely more interesting than any results to which their experiments
lead.
-- Norbert Wiener
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