[petsc-users] Weighted Jacobi, and scaling 2nd matrix in KSPSetOperators

[Timothée Nicolas]

Yes, exactly. I'm really sorry, I just sent the e-mail without thinking
enough... My bad.

Thanks

2016-02-22 15:28 GMT-07:00 Dave May <dave.mayhem23 at gmail.com>:

>
>
> On 22 February 2016 at 23:16, Timothée Nicolas <timothee.nicolas at gmail.com
> > wrote:
>
>> Hi all,
>>
>> It sounds it should be obvious but I can't find it somehow. I would like
>> to use weighted jacobi (more precisely point block jacobi) as a smoother
>> for multigrid, but I don't find the options to set a weight omega, after I
>> set -mg_levels_pc_type pbjacobi
>>
>
> Why not use  -ksp_type richardson -ksp_richardson_scale XXX ?
>
> Cheers,
>   Dave
>
> So I was thinking I could just artificially scale the second matrix in
>> KSPSetOperators with a weight omega. Since it is the one used in retrieving
>> the diagonal, it should be equivalent to have a weight and should not
>> affect the residuals, right ? However, I notice no change of behaviour
>> whatsoever when I do this.
>>
>> Is it normal ? Have I grossly misunderstood something ?
>>
>> Thanks
>>
>> Timothee
>>
>
>
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