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

[Xiaoye S. Li]

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/>
>
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