Re: [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: &nbsp;"Barry Smith"<bsm...@petsc.dev&gt;;
Date: &nbsp;Wed, Dec 30, 2020 03:12 AM
To: &nbsp;"朱昭霓"<zhuzhaoni2...@hnu.edu.cn&gt;; 
Cc: &nbsp;"petsc-users"<petsc-users@mcs.anl.gov&gt;; 
Subject: &nbsp;Re: [petsc-users] Error occurred when version change

&nbsp;



&nbsp; 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 &nbsp;do they now have the same SNES convergence?

&nbsp; Barry


On Dec 29, 2020, at 2:51 AM, 朱昭霓 <zhuzhaoni2...@hnu.edu.cn&gt; wrote:


Dear Sir or Madam:&nbsp;

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.&nbsp;

Best regards,

Zhaoni Zhu


<Error_report.jpg&gt;

3.4.5.docx
Description: Binary data

3.6.3.docx
Description: Binary data