[petsc-users] MatView and PetscViewerASCIIOpen problem when cpu > 1

[Jed Brown]

On Mon, Jun 25, 2012 at 12:25 PM, TAY wee-beng <zonexo at gmail.com> wrote:

> Hi,
>
> I'm trying to use DMDA to solve my linear equation.
>
> It works fine with 1 cpu. However, problem arise when cpu > 1. I get
> segmentation error.
>
> I tried to use  MatView and PetscViewerASCIIOpen to view my matrix to
> check if it's correct.
>
> It works with 1 cpu. However now, it shows the error below when I use 2
> cpu.
>
> [0]PETSC ERROR: --------------------- Error Message
> ------------------------------**------
> [0]PETSC ERROR: Argument out of range!
> [0]PETSC ERROR: ASCII matrix output not allowed for matrices with more
> than 1024 rows, use binary format instead.
> You can override this restriction using -mat_ascii_output_large.!
>
>  To view the matrix, my command is :
>
> call PetscViewerASCIIOpen(MPI_COMM_**WORLD,"A_semi.txt",viewer,**ierr)
>
> call MatView(A_semi,viewer,ierr)
>
> call PetscViewerDestroy(viewer,**ierr)
>
> I tried to use -mat_ascii_output_large but then it just hangs there
> forever.


It may just be very slow.

Why do you need ASCII? Writing anything large in ASCII is hopeless. Please
use binary.


> I create the matrix using DMCreateMatrix. I don't have to use
> MatCreateAIJ, right?
>
> Also, I check for the ierr value when I use MatSetValuesStencil to ensure
> there's no error. Btw There's no problem with VecView.
>
> So how can I view the matrix?
>
> Thank you!
>
> --
> Yours sincerely,
>
> TAY wee-beng
>
>
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