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

[Yujie]

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 at gmail.com> wrote:
>
> On Jan 22, 2008 8:50 PM, Yujie <recrusader at gmail.com> 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
> >
> >
> >
>
>
>
> --
> 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
>
>
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