Re: [petsc-dev] getting eigen estimates from GAMG to CHEBY

[Mark Adams via petsc-dev]

As I recall we attached the eigenstates to the matrix. Is that old attach
mechanism still the used/recommended? Or is there a better way to do this
now?
Thanks,
Mark

On Thu, Sep 26, 2019 at 7:45 AM Mark Adams  wrote:

>
>
>> Okay, it seems like they should be stored in GAMG.
>>
>
> Before we stored them in the matrix. When you get to the test in Cheby you
> don't have caller anymore (GAMG).
>
>
>> Why would the PC type change anything?
>>
>
> Oh, the eigenvalues are the preconditioned ones, the PC (Jacobi) matters
> but it is not too sensitive to normal PCs that you would use in a smoother
> and it is probably not an understatement.
>
>
>>
>>   Thanks,
>>
>> Matt
>> --
>> 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/
>> 
>>
>

Re: [petsc-dev] getting eigen estimates from GAMG to CHEBY

[Mark Adams via petsc-dev]

>
> Okay, it seems like they should be stored in GAMG.
>

Before we stored them in the matrix. When you get to the test in Cheby you
don't have caller anymore (GAMG).


> Why would the PC type change anything?
>

Oh, the eigenvalues are the preconditioned ones, the PC (Jacobi) matters
but it is not too sensitive to normal PCs that you would use in a smoother
and it is probably not an understatement.


>
>   Thanks,
>
> Matt
> --
> 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/
> 
>

[petsc-dev] getting eigen estimates from GAMG to CHEBY

[Mark Adams via petsc-dev]

It's been a few years since we lost the ability to cache the eigen
estimates, that smoothed aggregation computes, to chebyshev smoothers. I'd
like to see if we bring this back.

This is slightly (IMO) complicated by the fact that the smoother PC may not
be Jacobi, but I think it is close enough (and an overestimate probably).
Maybe provide a chevy option to chebyshev_recompute_eig_est.

What do people think?