Re: what's the difference between PetscViewerASCIIOpen() and PetscViewerBinaryOpen()?

[Yujie <recrusader@xxxxxxxxx>]

Dear Matt:

thank you for your reply. Do you have any method to generate an ascii file of the huge sparse matrix? thanks
 
Regards,
Yujie

On 1/23/08, Matthew Knepley <knepley@xxxxxxxxx> wrote:

On Jan 22, 2008 8:50 PM, Yujie <recrusader@xxxxxxxxx> wrote:
> Hi everyone:
>
> #include "petsc.h"
>  PetscErrorCode PetscViewerASCIIOpen(MPI_Comm comm,const char
> name[],PetscViewer *lab)
>
> #include "petsc.h"
>  PetscErrorCode PetscViewerBinaryOpen(MPI_Comm comm,const char
> name[],PetscFileMode type,PetscViewer *binv)
>
> if the difference between them is that one for ASCII output and the other
> for Binary output, why are there different parameters?

It is historical. If you want to be generic, you should use

  PetscViewerCreate()
  PetscViewerSetType()
  PetscViewerFileSetMode()
  PetscViewerFileSetName()

which can create both.

> The speed to output matrix is very fast when I use  PetscViewerBinaryOpen.
> However, when I use PetscViewerASCIIOpen, I can't get the matrix output. the
> code always is running and it has taken about one day! what's the problem?
> thank you.

ASCII files do not make sense for large matrices. You should use binary files.

   Matt

> Regards,
> Yujie
>
>
>



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