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 > > > > > >
