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<div dir="ltr">On Fri, Oct 19, 2018 at 4:02 AM Jan Grießer <<a href="mailto:griesser.jan@googlemail.com">griesser.jan@googlemail.com</a>> wrote:<br>
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<div dir="ltr">With more than 1 MPI process you mean i should use spectrum slicing in divide the full problem in smaller subproblems? <br>
The --with-64-bit-indices is not a possibility for me since i configured petsc with mumps, which does not allow to use the 64-bit version (At least this was the error message when i tried to configure PETSc )</div>
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<div class="gmail_quote">MUMPS 5.1.2 manual chapter 2.4.2 says it supports "Selective 64-bit integer feature" and "full 64-bit integer version" as well.
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<div dir="ltr">Am Mi., 17. Okt. 2018 um 18:24 Uhr schrieb Jose E. Roman <<a href="mailto:jroman@dsic.upv.es" target="_blank">jroman@dsic.upv.es</a>>:<br>
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To use BVVECS just add the command-line option -bv_type vecs<br>
This causes to use a separate Vec for each column, instead of a single long Vec of size n*m. But it is considerably slower than the default.<br>
<br>
Anyway, for such large problems you should consider using more than 1 MPI process. In that case the error may disappear because the local size is smaller than 768000.<br>
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Jose<br>
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> El 17 oct 2018, a las 17:58, Matthew Knepley <<a href="mailto:knepley@gmail.com" target="_blank">knepley@gmail.com</a>> escribió:<br>
> <br>
> On Wed, Oct 17, 2018 at 11:54 AM Jan Grießer <<a href="mailto:griesser.jan@googlemail.com" target="_blank">griesser.jan@googlemail.com</a>> wrote:<br>
> Hi all,<br>
> 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):
<br>
> The product 4001 times 768000 overflows the size of PetscInt; consider reducing the number of columns, or use BVVECS instead<br>
> 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 ?<br>
> <br>
> You can also reconfigure with 64-bit integers: --with-64-bit-indices<br>
> <br>
> Thanks,<br>
> <br>
> Matt<br>
> <br>
> Thank you very much in advance,<br>
> Jan <br>
> <br>
> <br>
> <br>
> -- <br>
> What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead.<br>
> -- Norbert Wiener<br>
> <br>
> <a href="https://www.cse.buffalo.edu/~knepley/" rel="noreferrer" target="_blank">
https://www.cse.buffalo.edu/~knepley/</a><br>
<br>
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