[petsc-users] An issue of extraction of factorization matrices in sparse direct solver

[Matthew Knepley]

On Thu, Oct 27, 2022 at 12:00 PM 赵刚 <zhaog6 at lsec.cc.ac.cn> wrote:

> Thank you Sherry for the triangular matrices extraction ways, it's very
> useful, I'll try to do this in SuperLU_DIST.
>
> In addition, Matthew, is it possible for PETSc to write interfaces that
> support printing `L` and `U` for SuperLU_DIST? Because it is very useful in
> some industrial application scenarios (store `L` and `U` in advance).
>
I think the way to do it would be to add support for this as the ASCII Mat
Viewer for that type. It would be a good contribution I think.

  Thanks,

     Matt

> Best Regards,
>
> Gang
>
>
> -----原始邮件-----
> *发件人:*"Xiaoye S. Li" <xsli at lbl.gov>
> *发送时间:*2022-10-25 05:47:15 (星期二)
> *收件人:* "Matthew Knepley" <knepley at gmail.com>
> *抄送:* "赵刚" <zhaog6 at lsec.cc.ac.cn>, petsc-users at mcs.anl.gov
> *主题:* Re: [petsc-users] An issue of extraction of factorization matrices
> in sparse direct solver
>
> There are some utility routines for printing L\U in superlu_dist:
> SRC/dutil_dist.c
>
>    1. You can output the L factor to a file with the triplet format by
>    using
>
>    https://github.com/xiaoyeli/superlu_dist/blob/324d65fced6ce8abf0eb900223cba0207d538db7/SRC/dutil_dist.c#L675
>    but use line 755 instead of line 753.
>    2. You can convert the L factor to CSR or triplet using
>    https://github.com/xiaoyeli/superlu_dist/blob/324d65fced6ce8abf0eb900223cba0207d538db7/SRC/dutil_dist.c#L815
>
>    https://github.com/xiaoyeli/superlu_dist/blob/324d65fced6ce8abf0eb900223cba0207d538db7/SRC/dutil_dist.c#L1075
>    but need to make sure you only use 1 MPI to call superlu_dist
>    3. You can modify
>
>    https://github.com/xiaoyeli/superlu_dist/blob/324d65fced6ce8abf0eb900223cba0207d538db7/SRC/dutil_dist.c#L1229
>    to generate CSR/triplet for the U factor as well.
>
>
> Sherry Li
>
> On Sun, Oct 23, 2022 at 3:38 AM Matthew Knepley <knepley at gmail.com> wrote:
>
>> On Sun, Oct 23, 2022 at 2:58 AM 赵刚 <zhaog6 at lsec.cc.ac.cn> wrote:
>>
>>> Dear developers,
>>>
>>> I have another question. How can I get the L and U matrices and store
>>> them in a file when I call SuperLU through PETSc? Thanks.
>>
>>
>> SuperLU stores these matrices in its own format. If you want to do I/O
>> with them, you would probably have to
>> extract them from the Petsc Mat and call SuperLU I/O functions, if they
>> exist.
>>
>>   Thanks,
>>
>>      Matt
>>
>>
>>> Best Regards,
>>> Gang
>>
>> --
>> 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/
>> <http://www.cse.buffalo.edu/~knepley/>
>>
>

-- 
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/ <http://www.cse.buffalo.edu/~knepley/>
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