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 > -- 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 -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20110304/c3648f67/attachment.htm>
