Dear Dr. Mitchell, Thanks for your reply. Yes, added linesearch_type:'bt' and it works. I also tried other SNES types and by saying snes_type: 'newtontr'or 'fas' solver converges even faster. For the default solver added snes_linesearch_monitor but it shows nothing. Thanks again. I don't have any problem anymore. Respectfully, Arash Sent from my BlackBerry 10 smartphone. Original Message From: Lawrence Mitchell Sent: Monday, September 28, 2020 6:36 PM To: arash pourakaberian Cc: firedrake@imperial.ac.uk Subject: Re: [firedrake] strange nonlinear solver divergence Dear Arash, we recently changed the default nonlinear solver linesearch (see the rationale here https://github.com/firedrakeproject/firedrake/pull/1471). It may be that this is the cause of your problem. Can you run with 'snes_linesearch_monitor': None You might also be able to reproduce the old behaviour by saying 'snes_linesearch_type': 'bt' Thanks, Lawrence
On 26 Sep 2020, at 21:01, arash pourakaberian <arashpourakaberian@gmail.com> wrote:
Dear Firedrake developer team,
I could not use streamplot, so updated the firedrake yesterday to fix the problem. It still doesn't work and additionally, I encounter a strange nonlinear solver divergence error for the same problem that it was able to solve before the package was updated. I don't know if the problem is due to petsc configuration or something else. Would you please help me resolve the issue? Two figures are attached to show the problem could be solved without error before the update. The text file attached shows the SNES monitor output. It is worth to mention the problem can still be solved when the gradient of the function at the top and bottom boundaries of the domain is not large. Thank you very much in advance.
Yours Sincerely,