Problem in convergence after upgrade to petsc 3.0.0

Randall Mackie rlmackie862 at
Fri Jan 30 20:37:50 CST 2009

Okay, but can you tell me why when I tried to turn off the positive definite shift
by adding:

-pc_factor_shift_positive_definite PETSC_FALSE

so that I'm consistent with the previous version of Petsc, I got the following

Invalid Argument!
Unknown logical value: PETSC_FALSE!

Thanks, Randy

Barry Smith wrote:
>   Run the old code with -ksp_view_binary this will create a file called 
> binaryoutput; you can then
> run src/ksp/ksp/examples/tutorials/ex10.c using that input file. Use the 
> ex10 from the old version
> of PETSc and then the ex10 from the new version. Do they have they same 
> convergence?
> Now run the new code (that is build your code with petsc-3.0.) with 
> -ksp_view_binary and run that
> binaryoutput file with the old and new ex10 to see what happens.
>    Basically there are two possible changes with the change in the version:
> 1) the matrix/right hand side has changed or
> 2) the solver has changed to behave differently.
>    By running the four cases you can start to get a handle on what has 
> actually changed, this will
> lead you to what needs to be investigated next.
>    Barry
> On Jan 30, 2009, at 8:01 PM, Randall Mackie wrote:
>> I just downloaded and compiled Petsc 3.0.0-p2, and after making some 
>> changes
>> in my code to specify the correct location of the include files, finally
>> got everything to compile okay.
>> Now, I'm trying to run my test problem, and it's not converging. When 
>> I say
>> not converging, the first line (with ksp_monitor_true_residual) shows 
>> that
>> the true and preconditioned residuals are the same as before, but 
>> immediately
>> thereafter, the preconditioned residual fails to go below 1e-8 whereas 
>> before
>> it quickly went down to 1e-15.
>> The options in my command file are:
>> -ksp_type bcgsl
>> -pc_type bjacobi
>> -sub_pc_type ilu
>> -sub_pc_factor_levels 3
>> -sub_pc_factor_fill 6
>> The only thing I see in the Change notes are that the ILU defaults to 
>> shifting
>> so that it's p.d. but I don't see an easy way to turn this off by the 
>> command
>> line to see if that's the problem. I tried to do it in my program, but 
>> it's unclear
>> if I did that correctly.
>> Any suggestions?
>> Thanks, Randy

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