[petsc-dev] PETSC application

[Barry Smith]

On Mar 7, 2010, at 10:57 AM, David sheehan wrote:

> >First, configure with Hypre .
> You mean, configure for the installation of PETSC with hypre? thanks.
    yes, add --download-hypre

>
> >Then -pc_type hypre -pc_hypre_type boomeramg
> You mean, without adding any information into code include, just  
> compile and link
> the code, to get an excuteable file, e.g. "a.out", then
> a.out -pc_type hypre -pc_hypre_type boomeramg
> is it right? thanks.

    Yes,

>
> >I cannot understand exactly what you mean. However, if you want to  
> create a PC
> > based upon a >matrix which is not the system matrix A, you can  
> specify it in
> > KSPSetOperators().
>
> I mean Ax =b doesn't have A in explicit form, but in expression A=B 
> +C1+C2+...+Cn,
> where B is main part of A in an explicity form, C1, C2,... and Cn  
> are small portions
> comparing with B and they don't have an explicit form. Thus I want   
> to  make a
> preconditioner from B, then apply the preconditioner to Ax=b. Please  
> tell me how I
> can do by PETSC sentences for PETSC solver, thanks.

    call KSPSetOperators(ksp,A,B,......)

    Barry


>
>
> David
>
>
> On Sun, Mar 7, 2010 at 12:32 AM, Matthew Knepley <knepley at gmail.com>  
> wrote:
> On Sat, Mar 6, 2010 at 11:49 PM, David sheehan <david.sheehanjr at gmail.com 
> > wrote:
> Hi,
> I need your helps about PETSC as follows:
> 1) how can I call boomerAMG of HYPRE through PETSC as a solver and a  
> preconditioner?
>
> First, configure with Hypre . Then -pc_type hypre -pc_hypre_type  
> boomeramg
>
> 2) how can I make a precondioner  from B matrix,  but apply the  
> preconditioner to Ax=b in PETSC?
> Thanks in advance.
>
> I cannot understand exactly what you mean. However, if you want to  
> create a PC based upon a matrix
> which is not the system matrix A, you can specify it in  
> KSPSetOperators().
>
>   Matt
>
> David
> -- 
> 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
>

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