[petsc-users] PetscInt overflow

[Jose E. Roman]

Sorry, running in parallel does not change the thing. I was wrong, the limitation is for the global size and not the local size. So what you have to do is use -bv_type vecs or also -bv_type mat
Let me know how this works.

Jose


> El 19 oct 2018, a las 13:12, Jan Grießer <griesser.jan at googlemail.com> escribió:
> 
> Thiis i already did with mpiexec -n 20 ... and there the error occured. I was also a little bit surprised that this error occured. Our computation nodes have 20 cores with 6GB RAM. 
> Is PETSc/ SLEPc saving the dense eigenvector error in one core ? 
> 
> 
> Am Fr., 19. Okt. 2018 um 12:52 Uhr schrieb Jan Grießer <griesser.jan at googlemail.com>:
> Thiis i already did with mpiexec -n 20 ... and there the error occured. I was also a little bit surprised that this error occured. Our computation nodes have 20 cores with 6GB RAM. 
> Is PETSc/ SLEPc saving the dense eigenvector error in one core ? 
> 
> Am Fr., 19. Okt. 2018 um 11:08 Uhr schrieb Jose E. Roman <jroman at dsic.upv.es>:
> No, I mean to run in parallel:
> 
> $ mpiexec -n 8 python ex1.py 
> 
> Jose
> 
> 
> > El 19 oct 2018, a las 11:01, Jan Grießer <griesser.jan at googlemail.com> escribió:
> > 
> > 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 <jroman at 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 <knepley at gmail.com> escribió:
> > > 
> > > 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/
> > 
>