[petsc-users] Questions On CGS iteration refinement in GMRES

[Matthew Knepley]

On Thu, Dec 3, 2020 at 11:16 AM 王一甲 <wangyijia at lsec.cc.ac.cn> wrote:

> To any one who it may concern:
>
> Hi, my name is Wang Yijia from Chinese Academy of Science. Recently I've
> been working on  some sparse linear system baseline tests using PETSc. When
> using gmres methods in KSP, I found that the option
> -ksp_gmres_cgs_refinement refine_always worked well on my sparse linear
> system, however I can not find more about how this process is done in the
> Hessenberg matrix generation(classical Gram-Schmidt process). I am curious
> about how the cgs iteration refinement process work in the whole KSP solve
> stage. I would appreciate it if you could offer some help.
>
The code is fairly short:


https://gitlab.com/petsc/petsc/-/blob/master/src/ksp/ksp/impls/gmres/borthog2.c

  Thanks,

     Matt


>
> Yours sincerely
>
>
> Wang Yijia
>
>
> 2020/12/3
>
>
>
>


-- 
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

https://www.cse.buffalo.edu/~knepley/ <http://www.cse.buffalo.edu/~knepley/>
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