[petsc-users] [PATCH 2/2] Call KSPSetFromOptions before setting fieldsplit-specific options

[Jed Brown]

Umut Tabak <u.tabak at tudelft.nl> writes:

> On 09/08/2013 05:03 PM, Dave May wrote:
>> It's stuck in  one of the inner solves. Turn on the montitors for 
>> fieldsplit_2
> ./ex3 -pc_type fieldsplit -pc_fieldsplit_type schur 
> -pc_fieldsplit_schur_factorization_type diag -fieldsplit_1_pc_type icc 
> -fieldsplit_1_ksp_type minres -fieldsplit_2_pc_type icc 
> -fieldsplit_2_ksp_type minres -fieldsplit_2_ksp_monitor_short 
> -ksp_converged_reason -ksp_monitor_short
>      Residual norms for fieldsplit_2_ solve.
>      0 KSP Residual norm 1.16308e+16
>      1 KSP Residual norm 1.05027e+16
>      2 KSP Residual norm 9.23221e+15
>      3 KSP Residual norm 7.11411e+15
>      4 KSP Residual norm 5.08588e+15
>      5 KSP Residual norm 2.55846e+15
>      6 KSP Residual norm 1.80045e+15

Looks like it's converging, albeit somewhat slowly, and your operator
scaling is terrible (not necessarily a problem, but full-space
fieldsplit methods work much better if you non-dimensionalize so that
the fields have similar scales).
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