[Trilinos-Users] [EXTERNAL] customizing Belos residual tests

[Jonas Thies]

Hello Heidi!

Maybe the exact scaling is not that important, but can I
scale by ||b|| rather than ||r_0||? I would expect these kind
of settings to be general for all solvers, but only GMRES seems to
have the parameters to do it. Shouldn't there always be an option to
set the status test manually?

Jonas


On 06/12/2012 06:08 PM, Thornquist, Heidi K wrote:
> Hi Jonas,
>
> Unfortunately, the specifiable convergence criteria for this solver will not give you the flexibility to create this residual test.  Furthermore, we do not include, in our standard convergence criteria, tests that include the norm of the solution vector.  So this would require the development of a specialized convergence test, which would not be too difficult for CG, since the solution vector is available.  The easiest change would be for this solver to implement the virtual setUserConvStatusTest() function from the base Belos::SolverManager class.  Then you can create this specialized convergence test and pass it in to this solver.  I can enable that functionality for this solver, if that would help.
>
> Thanks,
> Heidi
>
> ________________________________________
> From: trilinos-users-bounces at software.sandia.gov [trilinos-users-bounces at software.sandia.gov] on behalf of Jonas Thies [jonas at math.uu.se]
> Sent: Tuesday, June 12, 2012 7:54 AM
> Cc: trilinos-users at software.sandia.gov
> Subject: [EXTERNAL] [Trilinos-Users] customizing Belos residual tests
>
> Hi all,
>
> I would like to compare the convergence and performance of
> Belos to some native solvers in an application.
> To do that I would like to use the BlockCGSolMgr and a convergence criterion
>
> ||A*x-b||_2 / (||A||_F ||x||_2 + ||b||_2)<  tol
>
> Is that possible without hacking in the Belos source itself?
>
> Thanks!
> Jonas
>
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-- 
Jonas Thies
Centre for Interdisciplinary Mathematics
Uppsala University
phone +46 (0)18 471 32 09