[petsc-users] how to write the symmetric matrix in PETSc binary

[Satish Balay]

check http://www.mcs.anl.gov/petsc/petsc-as/documentation/faq.html#sparse-matrix-ascii-format

satish

On Fri, 4 Mar 2011, Matthew Knepley wrote:

> On Fri, Mar 4, 2011 at 5:24 PM, <ning.an at ghiocel-tech.com> wrote:
> 
> > Dear Knepley,
> >
> >          Thanks for your quick response.
> >
> >          Yes, I have not pre-allocated sufficient space for the matrix,
> > since I don't know the max. bandwidth. I got this matrix from other person.
> > My task is to test PETSc solver for huge matrix size. I'm going to ask the
> > person to give me that number. base on your experience, how fast could it be
> > if I use "call  MatCreateSeqAIJ(comm,n,n,rowmax,PETSC_NULL,&mat)" ?
> 
> 
> That will be fast as long as no row is greater than rowmax long. However,
> why not just count first? This is easy and fast.
> 
> 
> >
> >            Since I don't have the PETSc matrix yet, I couldn't use
> > MatView() to write it in the binary format. Do you have another suggestion
> > to generate matrix file in PETSc binary format? I'm not familiar with C. I
> > couldn't dig it out from the source code. It is so appreciated If you get me
> > an example.
> >
> 
> The C is the only reference.
> 
>   Matt
> 
> 
> >           Have a good weekend.
> >
> >           ning
> >
> > ----- Original Message -----
> > *From:* knepley at gmail.com
> > *To:* petsc-users at mcs.anl.gov
> > *Sent:* 3/4/11 5:44 PM
> > *Subject:* Re: [petsc-users] how to write the symmetric matrix in PETSc
> > binary
> >
> >  On Fri, Mar 4, 2011 at 4:40 PM, <ning.an at ghiocel-tech.com> wrote:
> >
> >> Hello There,
> >>
> >>  I am new to PETSc and programming with FORTRAN. For the huge sparse
> >> matrix  (200,000x200,000 symmetric), it is so slow to set the matrix in
> >> PETSc by reading them in matrix market format, which is far beyond our
> >> patience. Therefore, I guess that it would be much  fast to load the huge
> >> matrix, if the matrix is in PETSc binary matrix format
> >>  directly.
> >>
> >
> > It is probably slow because you have not preallocated the matrix
> > correctly:
> > http://www.mcs.anl.gov/petsc/petsc-as/documentation/faq.html#efficient-assembly
> >
> >
> >>  Please help on how to write the symmetric matrix in PETSc binary matrix
> >> format directly?
> >>
> >
> > You just save it using MatView(). For example:
> >
> >
> > http://www.mcs.anl.gov/petsc/petsc-as/snapshots/petsc-current/src/ksp/pc/examples/tutorials/ex2.c.html
> >
> >   Matt
> >
> >
> >>  Both the guidance and examples are welcome.
> >>
> >> Ning
> >
> > --
> > 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
> >
> 
> 
> 
>