PCNN preconditioner

Andreas Grassl Andreas.Grassl at student.uibk.ac.at
Fri Mar 6 02:20:27 CST 2009

Barry Smith schrieb:
>     For the subdomain solves the prefix are is_localD_ and is_localN_
> so you should use the options
> -is_localD_pc_factor_shift_positive_definite and
> -is_localN_pc_factor_shift_positive_definite

With both options it is working now.

>    There is currently no subroutine that "pulls out" the inner KSP's for
> the
> Neuman and Dirichlet problems for use in the code; though there should be
> PCISGetDPC() and PCISGetNPC() that would get the pointer to ksp_N and ksp_D
> objects inside the PC_IS data structured defined in
> src/ksp/pc/impls/is/pcis.h
> You can easily add these routines. Then use them to get the inner PC and
> set
> the shift option (and anything else you want to set).

I'll try later, for now I'm happy with the options

Thank you for helping, I'll give some feedback



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