[petsc-dev] PETSC_COMM_WORLD declaration

[Matthew Knepley]

On Sun, May 17, 2015 at 11:30 PM, Marco Zocca <zocca.marco at gmail.com> wrote:

> What does this declaration in petscsys.h do?
>
> What type and value does PETSC_COMM_WORLD expand to?
>

The type is MPI_Comm. If you mean what basic type, that is up to the MPI
implementation. However, I think you can assume that it fits in a (void *).

The value is obtained at runtime from MPI_Comm_dup or from user input.

  Thanks,

     Matt


> #define PETSC_EXTERN extern PETSC_VISIBILITY_PUBLIC
>
> PETSC_EXTERN MPI_Comm PETSC_COMM_WORLD;
>
>
> Thank you in advance,
> Marco
>

-- 
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
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