[petsc-users] PetscInt overflow

[Matthew Knepley]

On Wed, Oct 17, 2018 at 11:54 AM Jan Grießer <griesser.jan at googlemail.com>
wrote:

> Hi all,
> i am using slepc4py and petsc4py to solve for the smallest real
> eigenvalues and eigenvectors. For my test cases with a matrix A of the size
> 30k x 30k solving for the smallest soutions works quite well, but when i
> increase the dimension of my system to around A = 768000 x 768000 or 3
> million x 3 million and ask for the smallest real 3000 (the number is
> increasing with increasing system size) eigenvalues and eigenvectors i get
> the output (for the 768000):
>  The product 4001 times 768000 overflows the size of PetscInt; consider
> reducing the number of columns, or use BVVECS instead
> i understand that the requested number of eigenvectors and eigenvalues is
> causing an overflow but i do not understand the solution of the problem
> which is stated in the error message. Can someone tell me what exactly
> BVVECS is and how i can use it? Or is there any other solution to my
> problem ?
>

You can also reconfigure with 64-bit integers: --with-64-bit-indices

  Thanks,

    Matt


> Thank you very much in advance,
> Jan
>
>

-- 
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

https://www.cse.buffalo.edu/~knepley/ <http://www.cse.buffalo.edu/~knepley/>
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