With more than 1 MPI process you mean i should use spectrum slicing in divide the full problem in smaller subproblems? 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 )
Am Mi., 17. Okt. 2018 um 18:24 Uhr schrieb Jose E. Roman <jro...@dsic.upv.es >: > To use BVVECS just add the command-line option -bv_type vecs > 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. > > 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. > > Jose > > > > El 17 oct 2018, a las 17:58, Matthew Knepley <knep...@gmail.com> > escribió: > > > > On Wed, Oct 17, 2018 at 11:54 AM Jan Grießer < > griesser....@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/ > >
