[petsc-users] Mixed 32-bit and 64-bit indices

[Daniel Langr]

In parallel (12 processes minimum), so it should work :) Thanks a lot,

Daniel


Dne 8.11.2010 11:22, Jed Brown napsal(a):
> On Mon, Nov 8, 2010 at 09:05, Daniel Langr <daniel.langr at gmail.com
> <mailto:daniel.langr at gmail.com>> wrote:
>
>     is there any way to use 32-bit integers for indexing rows/columns
>     and 64-bit integers for indexing nonzeros at the same time in PETSc?
>     I have a matrix with 4,559,168,066 nonzeros but only 448,797
>     rows/columns. For a general CSR scheme, the memory savings are
>     almost 25% when using 32-bit integers compared to 64-bit for
>     indexing columns, which is really a lot of memory.
>
>
> Are you running in serial?  As long as the local part of any matrix has
> less than 2B entries (which would cost more than 24 GiB to store) and
> the global problem has dimension less than 2B, you should be fine using
> 32-bit indices.
>
> Jed