[petsc-users] multiplication of large matrices using MatMatMult

[Reza Madankan]

Yes, the matrix is dense. So, you mean that there is no way to evaluate the
matrix, exactly? .... I have run the code for smaller size of Ypcq and it's
working. But for larger sizes I get the error that I mentioned.
On Jan 2, 2012 6:24 PM, "Jed Brown" <jedbrown at mcs.anl.gov> wrote:

> On Mon, Jan 2, 2012 at 17:16, Reza Madankan <rm93 at buffalo.edu> wrote:
>
>> I am trying to compose a covariance matrix which is of size 72576 x
>> 72576, by multiplication of a vector and its transpose, i.e.
>>
>> MatMatMult(Ypcq,YpcqT,MAT_INITIAL_MATRIX,PETSC_DEFAULT,&InnProd)
>>
>> where, Ypcq is a vector with 72576 elements and YpcqT is its transpose.
>>
>
> This matrix is dense, right? Would you consider something less than the
> full covariance matrix, such as a low rank approximation?
>
>
>> Unfortunately Petsc returns out of memory message while running the code:
>>
>>
>>  [0]PETSC ERROR: --------------------- Error Message
>> ------------------------------------
>> [0]PETSC ERROR: Out of memory. This could be due to allocating
>> [0]PETSC ERROR: too large an object or bleeding by not properly
>> [0]PETSC ERROR: destroying unneeded objects.
>> [0]PETSC ERROR: Memory allocated 0 Memory used by process 15732801536
>> [0]PETSC ERROR: Try running with -malloc_dump or -malloc_log for info.
>>  [0]PETSC ERROR: Memory requested 18446744068420534272!
>>
>
> These huge numbers indicate memory corruption somewhere. I suggest running
> a smaller problem size under Valgrind.
>
>
>
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