[petsc-users] How to implement projection preconditioner?

[Abdul Hanan Sheikh]

Thanks for reply! 

Well at first look, it looks like that M can be put as precondittioning operator for smoother
where keeping ksp as preonly in pre-smoother context. 
I am not sure, this leads to the preconditioner desired, coz putting M as preconditioner in 

pre-smoother alters the residual passed to coarse-grid correction,  i.e. 

CGC corrects the pre-smoothed solution. 






>________________________________
> From: Jed Brown <jedbrown at mcs.anl.gov>
>To: Abdul Hanan Sheikh <hanangul12 at yahoo.co.uk>; PETSc users list <petsc-users at mcs.anl.gov> 
>Cc: Abdul - CITG <A.H.Sheikh at tudelft.nl> 
>Sent: Friday, 8 June 2012, 19:01
>Subject: Re: [petsc-users] How to implement projection preconditioner?
> 
>
>Isn't this just putting M and M_H as the preconditioning operator for the smoother?
>
>
>On Fri, Jun 8, 2012 at 11:58 AM, Abdul Hanan Sheikh <hanangul12 at yahoo.co.uk> wrote:
>
>Dear all, 
>>
>>Summer greetings, 
>>
>>I am back with an other query.
>>Before I successfully implement the projection preconditioner which was simply 
>>
>>the coarse grid correction operator P = I - A*(P*A_H*R); 
>>
>>I implemented this simply keeping both pre and post smoothing dummy in PCMG setup. 
>>
>>Now I need to revise this and re-implement this where I replace A and coarse operator A_H with 
>>
>>preconditioned one i.e. M^-1 A and M^-1 A_H respectively. Thus new projection reads as
>>
>>
>>
>>
>>P_new = I - (M^-1 A) {P*(M_H^-1 A_H)*R}
>>
>>
>>Any suggestion to implement this in Petsc would be appreciated. 
>>
>>
>>
>>Thanking in anticipation. 
>>
>>with regards, Abdul 
>>
>
>
>
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