On Sun, May 17, 2015 at 11:30 PM, Marco Zocca <[email protected]> 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