[petsc-users] SNES with constraint diverges

[Josh L]

The following is the output. Thanks.

  0 SNES Function norm 3.775139483936e-07
      Line search: Using full step: fnorm 3.775139483936e-07 gnorm
1.043499007769e-11
  1 SNES Function norm 1.043499007769e-11
      Line search: Using full step: fnorm 1.043499007769e-11 gnorm
5.302082026305e-12
  2 SNES Function norm 5.302082026305e-12
      Line search: Using full step: fnorm 5.302082026305e-12 gnorm
3.136358665117e-12
  3 SNES Function norm 3.136358665117e-12
      Line search: Using full step: fnorm 3.136358665117e-12 gnorm
2.170819065257e-12
  4 SNES Function norm 2.170819065257e-12
      Line search: Using full step: fnorm 2.170819065257e-12 gnorm
1.475760790713e-12
  5 SNES Function norm 1.475760790713e-12
      Line search: Using full step: fnorm 1.475760790713e-12 gnorm
1.130642522675e-12
  6 SNES Function norm 1.130642522675e-12
      Line search: Using full step: fnorm 1.130642522675e-12 gnorm
8.647827205825e-13
  7 SNES Function norm 8.647827205825e-13
      Line search: Using full step: fnorm 8.647827205825e-13 gnorm
7.403983354386e-13
  8 SNES Function norm 7.403983354386e-13
      Line search: Using full step: fnorm 7.403983354386e-13 gnorm
6.291615062788e-13
  9 SNES Function norm 6.291615062788e-13
      Line search: Using full step: fnorm 6.291615062788e-13 gnorm
5.682820624094e-13
 10 SNES Function norm 5.682820624094e-13
      Line search: Using full step: fnorm 5.682820624094e-13 gnorm
5.300267435005e-13
 11 SNES Function norm 5.300267435005e-13
      Line search: Using full step: fnorm 5.300267435005e-13 gnorm
5.096339188439e-13
 12 SNES Function norm 5.096339188439e-13
      Line search: Using full step: fnorm 5.096339188439e-13 gnorm
4.970340343183e-13
 13 SNES Function norm 4.970340343183e-13
      Line search: Using full step: fnorm 4.970340343183e-13 gnorm
4.916509482510e-13
 14 SNES Function norm 4.916509482510e-13
      Line search: Using full step: fnorm 4.916509482510e-13 gnorm
4.875840608086e-13
 15 SNES Function norm 4.875840608086e-13
      Line search: Using full step: fnorm 4.875840608086e-13 gnorm
4.859609948396e-13
 16 SNES Function norm 4.859609948396e-13
      Line search: Using full step: fnorm 4.859609948396e-13 gnorm
4.846457390135e-13
 17 SNES Function norm 4.846457390135e-13
      Line search: Using full step: fnorm 4.846457390135e-13 gnorm
4.840667643605e-13
 18 SNES Function norm 4.840667643605e-13
      Line search: Using full step: fnorm 4.840667643605e-13 gnorm
4.837878467904e-13
 19 SNES Function norm 4.837878467904e-13
      Line search: Using full step: fnorm 4.837878467904e-13 gnorm
4.835385298533e-13
 20 SNES Function norm 4.835385298533e-13
      Line search: Using full step: fnorm 4.835385298533e-13 gnorm
4.833767981145e-13
 21 SNES Function norm 4.833767981145e-13
      Line search: Aborted due to ynorm < stol*xnorm (6.489173391862e-15 <
2.387840730261e-06) and inadequate full step.
Nonlinear smu_ solve did not converge due to DIVERGED_LINE_SEARCH
iterations 21




2018-09-11 23:37 GMT-05:00 Smith, Barry F. <bsmith at mcs.anl.gov>:

>
>    Do you start with initial conditions of  0 <= u_i <= 1 ?
>
>     Run with -snes_monitor -snes_converged_reason
> -ksp_monitor_true_residual -info -snes_linesearch_monitor and send all the
> output
>
>   Barry
>
>
> > On Sep 11, 2018, at 11:33 PM, Josh L <ysjosh.lo at gmail.com> wrote:
> >
> > Hi,
> >
> > I am using SNES to solve an nonlinear equation f(u), and I know all the
> u_i should be 0 and 1.
> >
> > First, I use SNES without constraint, and it converges.
> >
> > But, If I set
> >      SNESSetType(snes,SNESVINEWTONRSLS,ierr)
> >      SNESVISetVariableBounds(snes,xl,xu,ierr)
> >
> > where xl and xu is vector, and xl_i=0 and xu_i=1
> >
> > then SNES fails to converge, because linesearch fails(snes reason = -6),
> and the norm of residual is not reducing(the norm of incremental solution
> is reducing)
> >
> > The reason to add constraint is that I want to implement some
> irreversibility.
> >
> >
> > Thanks,
> > Josh
> >
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20180912/cb3418b9/attachment-0001.html>