ell1 norm convergence test

[Ryan Yan]

Hi Matt,
Thanks for the pointer.

Yan

On Mon, Sep 21, 2009 at 2:40 PM, Matthew Knepley <knepley at gmail.com> wrote:

> You can use KSPBuildResidual().
>
>   Matt
>
>
> On Mon, Sep 21, 2009 at 12:44 PM, Ryan Yan <vyan2000 at gmail.com> wrote:
>
>> Hi All,
>> The following question is only for test and comparison reason.
>>
>> Is there a command line option to set up using 1-Norm(sum of absolute
>> value of residuals)  as convergence monitor and test.
>>
>> Alternatively, if I can get the residual "r" out at the end of each
>> iteration, then it is going to be much simpler, since I can just call
>> VecNorm(r, NORM_1, &r_ell1) and pass the r_ell1 into the convergence monitor
>> and test. Can anyone inform me if PETSc has an interface for the resuidual
>> r?
>>
>> Or one has to call the convergence test:
>> MyKSPConverged(ksp,n,rnorm,flag,dummy);
>> and following the steps:
>> 1. fetch the exact solution:
>>
>> KSPBuildSolution(ksp,PETSC_NULL_OBJECT,x,ierr)
>>
>> 2. calculate the residual:
>>
>> pass the Right Hand side and the Matrix in to calculate the 1-Norm. But
>> this step is *not* obvious, since the matrix and rhs is already distributed
>> over each processes.
>>
>> 3. set up the convergence test based on the 1_Norm residual.
>>
>>
>> Thank you very much,
>>
>>
>> Yan
>>
>
>
>
> --
> What most experimenters take for granted before they begin their
> experiments is infinitely more interesting than any results to which their
> experiments lead.
> -- Norbert Wiener
>
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