The files should be the same.
Barry
1) If the matrix is generated differently in parallel then sequential then rounding of the floating point operations will result in very slightly different numerical values in the matrix.
2) If the ordering of the the unknowns is different in the parallel and sequential then the matrices will, of course, be permutations of each other.
On Feb 12, 2008, at 1:06 PM, Yujie wrote: hi, Matt
If I output matrix with binary format, should the file format obtained from sequential output is the same with that from parallel output? I mean that I don't need to consider whether MatView_***_Binary() is parallel or sequential when I use the matrix file.
thanks a lot.
Regards,
Yujie
On 1/23/08, Matthew Knepley <knepley@xxxxxxxxx> wrote: On Jan 23, 2008 2:18 PM, Yujie <recrusader@xxxxxxxxx> wrote:
> Thank you for your further explanation. I just want to use this data in
> other packages. I think that ASCII file is likely better. Because I don't
> know the format of the binary file? how to find it?
Look at MatView_SeqAIJ_Binary() in src/mat/impls/aij/seq/aij.c. The
format is pretty simple.
> In addition, do you have any better methods to save the sparsity structure
> picture of the matrix? Now, I use "-mat_view_draw" to do this. However, the
> speed is very slow and the picture is small. I want to get a big picture and
> directly save it to the disk?
> could you give me some advice? thanks a lot.
We do not have a better way to make the sparsity picture. I assume you could
write something that decides how many pixels to use, calculates an average
occupancy per pixel, and writes a BMP or something.
Matt
> Regards,
> Yujie
>
> On 1/23/08, Matthew Knepley <knepley@xxxxxxxxx > wrote:
> > On Jan 22, 2008 11:01 PM, Yujie <recrusader@xxxxxxxxx> wrote:
> > > Dear Matt:
> > >
> > > thank you for your reply. Do you have any method to generate an ascii
> file
> > > of the huge sparse matrix? thanks
> >
> > I think you miss my point. The PETSc function is not a bad way to generate
> > ASCII matrices. ASCII matrices make "no sense" for large operators.
> >
> > Matt
> >
> > > 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
> > > > >
> > > > >
> > > > >
> > > >
> > > >
> > > >
> > > > --
> > > > 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
> > > >
> > > >
> > >
> > >
> >
> >
> >
> > --
> > 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
> >
> >
>
>
--
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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