[petsc-users] Data types for local ID's and global ID's for large problems

[Matthew Knepley]

On Wed, Jan 9, 2019 at 5:53 PM Weston, Brian Thomas via petsc-users <
petsc-users at mcs.anl.gov> wrote:

> Does PETSc have different data types for local ID’s and global ID’s? For
> example, if PETSc is configured for 32-bit indices on very large problems
> with say 10 billion degrees of freedoms (exceeding the limit of 32-bit
> indices for a global ID) would it crash and require us to re-compile with
> 64-bit indices or can it gracefully handle this?
>

You would need to reconfigure for 64-bit indices. Keeping local indices
32-bit does not do much. I experimented with a local-index-only version
several years ago, but it breaks a lot of things, and does not really
deliver much benefit.

  Thanks,

    Matt


> Sincerely,
>
> Brian
>


-- 
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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