[petsc-dev] [petsc-users] Any suggestion for this kinds of matrix?

[Mark F. Adams]

On Nov 10, 2011, at 4:02 PM, Barry Smith wrote:

> 
>   Maybe in the debug version of PETSc -ksp_monitor should turn on true residual monitoring? 
> 
>   Barry
> 
> On Nov 10, 2011, at 2:49 PM, Jed Brown wrote:
> 
>> On Thu, Nov 10, 2011 at 14:45, Bao Kai <paeanball at gmail.com> wrote:
>> PCFIELDSPLIT seems a little more complex, I will try that. 
>> 
>> I tried some different preconditioners, only lu can get right results. 
>> 
>> With some pc, some wrong results can be obtained, such as the following one.  
>> 
>> tutorials]$ time ./ex78 -Ain A_in -rhs rhs -solu solu -noshift -pc_type hypre -pc_hypre_type parasails -ksp_gmres_restart 600 -ksp_rtol 1e-5 -ksp_typ gmres
>> 
>> Always run with -ksp_monitor_true_residual -ksp_converged_reason when checking whether a preconditioner is working.
> 
> 

Would this problem also be fixed with -ksp_norm_type unpreconditioned ???

In that case you could make this the default for debug and not debug, which is cleaner (I've never figured out why you even offer preconditioned norm as an option, much less the default)