[petsc-users] Does float128 helps ksp solver convergence

[Matthew Knepley]

On Sun, Sep 18, 2011 at 10:07 AM, Gong Ding <gdiso at ustc.edu> wrote:

>
>
> 2011/9/18 Gong Ding <gdiso at ustc.edu>
>
>> Hi,
>> I always meed some linear system with condition number near 1e10, the ksp
>> solver (BCGSL + ASM + ILU(1))with double presision
>> seems painful to convergence.
>>
>
> Higher precision is unlikely to affect the convergence rate. It might help
> with loss of orthogonality.
>
> Do you mean GMRES-like method will be benefited from float 128?
>
> My guess is no, but it is possible.

   Matt


>    Matt
>
>
>> Will float 128 helps in this situation?
>> And how about the performance degenerate for float 128 under i.e. XEON
>> 5620 CPU compared with double?
>>
>> Thanks
>> Gong Ding
>>
>>
>
>
> --
> 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
>
>


-- 
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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