Thanks for the clarification. Petsc saves me a lot of time not having to write 
the icc etc so i can live with these small issues very well. Petsc behaves as 
expected now.
Danny

Sent from my iPad

> On 29 mei 2014, at 22:04, "Barry Smith" <[email protected]> wrote:
> 
> 
>  Danny,
> 
>   The manual pages are a little sloppy and inconsistent. By default it uses 
> ||b|| or || preconditioned b|| as the starting point. At the bottom of the 
> badly formatted page you’ll see "- - rnorm_0 is the two norm of the right 
> hand side. When initial guess is non-zero you can call 
> KSPDefaultConvergedSetUIRNorm() to use the norm of (b - A*(initial guess)) as 
> the starting point for relative norm convergence testing."
> 
> Likely you want to call KSPDefaultConvergedSetUIRNorm if that is how you want 
> to detect convergence.
> 
>   We’ll cleanup the manual pages, thanks for pointing out the confusion.
> 
>   Barry
> 
>  You can see the source code at 
> http://www.mcs.anl.gov/petsc/petsc-current/src/ksp/ksp/interface/iterativ.c.html#KSPDefaultConverged
>  and confirm that what Matt said is correct.
> 
> 
>> On May 29, 2014, at 2:49 PM, Danny Lathouwers - TNW 
>> <[email protected]> wrote:
>> 
>> Thanks Matt for your quick response.
>> 
>> I got to believe that it was the relative ratio of the residual from the 
>> following petsc links:
>> 
>> http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/KSP/KSPSetTolerances.html
>> and
>> http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/KSP/KSPDefaultConverged.html#KSPDefaultConverged
>> 
>> Perhaps these pages are outdated?
>> 
>> Cheers,
>> Danny.
> 

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