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)" ?
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.
Have a good weekend.
ning
----- Original Message -----
From: knepley at gmail.comTo: 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
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