Thanks a lot! =) 2009/9/15 Matthew Knepley <knepley at gmail.com>
> You can use the output of -ksp_view, which gives the matrix information. > > Matt > > > On Tue, Sep 15, 2009 at 2:01 PM, Bernardo Rocha <bernardosk at > gmail.com>wrote: > >> Hi everyone, >> >> I need to know the number of nonzero element of the matrix in an >> application using PETSc. How can I do it? What is the best way to do it? >> >> As far as I'm concerned with PETSc, running on a single processor, I'm >> using the command line argument "-info" and then I get this information in >> some line of the output that looks like this >> >> [0] MatAssemblyEnd_SeqAIJ(): Matrix size: 5100 X 5100; storage space: >> 92706 unneeded,44994 used >> >> then I simply get the number of used entries. >> >> But when I have a large simulation, where the matrix does not fit into the >> memory of one processor, I must use several processors. My question is how >> to get the number of nonzero entries of the "global" matrix? I wrote a >> simple python script to parse the output and sum the number of entries used >> on each processor, but I found out that my calculations are wrong, I'm >> having twice more nonzero elements (I tested against a tiny simulation on a >> single processor). It seems that on the output I'm parsing I have two kinds >> of informations about the entries used: >> >> [0] MatAssemblyEnd_SeqAIJ(): Matrix size: 5100 X 5100; storage space: >> 92706 unneeded,44994 used >> >> [0] MatAssemblyEnd_SeqAIJ(): Matrix size: 5100 X 5100; storage space: 0 >> unneeded,44994 used >> >> That is, one that the "unneeded" field has some value and another that >> this field is zero. Then I decided to discard the information where the >> field "unneeded" is zero and finally the results matched perfectly with a >> single processor case. >> >> So, i would like to know (1) why do I have these lines with "0 unneeded" >> and (2) if there is a more elegant way to measure this. >> >> That's all! >> Best regards, >> Bernardo M. R. >> > > > > -- > 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/20090915/dc7aef02/attachment.htm>
