[petsc-users] Petsc Binary Write - Memory

[Matthew Knepley]

On Wed, Jun 10, 2015 at 8:32 AM, venkatesh g <venkateshgk.j at gmail.com>
wrote:

> The size of the matrix is 84500 x 84500
>
> the no. of non-zero elements is 2.7338e+09
>

This matrix is not sparse, it has 40% fill. You should treat it as dense.
For dense matrices of this size,
you should consider using Elemental. We have an interface to Elemental in
PETSc.

I recommend writing the code to create these entries on the fly since it
will probably be faster than loading
them from disk.

  Thanks,

    Matt


> cheers,
> Venkatesh
>
> On Wed, Jun 10, 2015 at 6:35 PM, Satish Balay <balay at mcs.anl.gov> wrote:
>
>> Whats the size of the matrix? How many non-zeros?
>>
>> Satish
>>
>> On Wed, 10 Jun 2015, venkatesh g wrote:
>>
>> > Hi
>> >
>> > I am trying to write very large sparse matrices A and B for solving
>> > generalized Eigenvalue problem
>> >
>> > so that I can use SLEPC ex7.c code.
>> >
>> > I want to read matrices from file according to that code. And I generate
>> > these matrices from Matlab using PetscBinaryWrite.m
>> >
>> > However, it exceeds my 256 GB RAM in one of the machines. So I am
>> unable to
>> > generate these binary matrices.
>> >
>> > Kindly let me know how to write them efficiently.
>> >
>> > cheers,
>> >
>> > Venkatesh
>> >
>>
>>
>


-- 
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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