[petsc-users] Implementation of Multilevel preconditioner

[Abdul Hanan Sheikh]

>________________________________
> From: Jed Brown <jedbrown at mcs.anl.gov>
>To: Abdul Hanan Sheikh <hanangul12 at yahoo.co.uk> 
>Cc: PETSc users list <petsc-users at mcs.anl.gov> 
>Sent: Thursday, 5 April 2012, 20:17
>Subject: Re: [petsc-users] Implementation of Multilevel preconditioner
> 
>
>On Thu, Apr 5, 2012 at 11:12, Abdul Hanan Sheikh <hanangul12 at yahoo.co.uk> wrote:
>
>Recursive two level multigrid  (by using PCMG with my desired stuff in it, in PCSHELL) is okay. I will do it recursively. 
>>No Problem with recursion and nested iterations. 
>>Coming to two level, 
>>How can I get exactly Prec = C +  M^-1 (I - A*C) in a two level multigrid ? 
>>What should be specific choice of pre_smoother_ksp_context and post_smoother_ksp_context 
>>to get the "Prec" ? 
>>what operators should be chosen in these two ksp contexts ? 
>
>This is just -pc_mg_type kaskade (zero pre-smoothing iterations, one post-smoothing iteration).Thanks. and cleared!
>
>
>Post-smoothing context details would be appreciated! 
>To my understing, those would be: 
>1 post-smoothing iteration with 
>KSP type Richardson 
>PC type to be applied on M is PCShellForM (say there PCLU in PCShellForM, though I need to change this, so I say this) . 
>
>
>This will complete my preconditioner "Prec" ?? 
>
>
>Bundle of thanks, 
>Abdul 
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