[petsc-users] Question about MatView

[Matthew Knepley]

On Fri, Mar 17, 2023 at 5:51 AM user_gong Kim <ksi2443 at gmail.com> wrote:

> Hello,
>
>
>
> I have 2 questions about MatView.
>
>
>
> 1.    I would like to ask if the process below is possible.
> When running in parallel, is it possible to make the matrix of the mpiaij
> format into a txt file, output it, and read it again so that the entire
> process has the same matrix?
>
No. However, you can do this with a binary viewer. I suggest using

  MatViewFromOptions(mat, NULL, "-my_view");

and then the command line argument

  -my_view binary:mat.bin

and then you can read this in using

  MatCreate(PETSC_COMM_WORLD, &mat);
  PetscViewerBinaryOpen(PETSC_COMM_WORLD, "mat.bin", FILE_MODE_READ,
&viewer);
  MatLoad(mat, viewer);
  ViewerDestroy(&viewer);

  THanks,

     Matt



> 2.    If possible, please let me know which function can be used to
> create a txt file and how to read the txt file.
>
>
>
> Thanks,
>
> Hyung Kim
>


-- 
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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