[petsc-users] Error occurred when version change

[朱昭霓]

Dear Smith,


  Thank you so much for your prompt reply! I have confirmed that the parameters of the linear resolver in these two versions are the same and I also run the code with -pc_type lu. It disconverges after the first two time steps, showing "line search fails" (I have printed the running results using 3.6.3 and 3.4.5 versions in the following attachment). I wonder if there are some inner functions or parameters which changes with different versions leading to the disconvergence in 3.4.5 version ? 


Best regards,
Zhaoni Zhu


 
 
------------------ Original ------------------
From:  "Barry Smith"<bsmith at petsc.dev>;
Date:  Wed, Dec 30, 2020 03:12 AM
To:  "朱昭霓"<zhuzhaoni2017 at hnu.edu.cn>; 
Cc:  "petsc-users"<petsc-users at mcs.anl.gov>; 
Subject:  Re: [petsc-users] Error occurred when version change

 



  It looks like both converged in your image, just at different rates? Note the two sides used different number of linear iterations, my guess is some default behavior of the linear solvers changed between those two ancient releases. First make sure both are using identical linear solvers. Then run both with -pc_type lu  do they now have the same SNES convergence?

  Barry


On Dec 29, 2020, at 2:51 AM, 朱昭霓 <zhuzhaoni2017 at hnu.edu.cn> wrote:


Dear Sir or Madam: 

Hello, I am a new PETSc learner. There are some confusions when I using different versions of PETSc. For some reasons, I have to change my codes from the version 3.6.3 to 3.4.5. Newton methods in 3.6.3 version converged successfully with the time step size dt=100. While with the same dt=100 and almost the same codes, Newton methods in version 3.4.5 failed to converge. The debug test indicated that there may be something wrong during the line search process. I have tried to search the changes in different versions but failed. Could you please give me some suggestions? Thank you so much. 

Best regards,

Zhaoni Zhu


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