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MPI provides both Fortran and C routines.
All names of MPI routines and constants in both C and Fortran
begin with the prefix MPI_ to avoid name collisions.
For the remainder of this guide, only the C versions of the MPI routines will be presented.
However, the primary differences between the C and Fortran routines are:
- Error codes are returned in a separate argument for Fortran
as opposed to the return value for C functions.
- Fortran-compatible MPI routine names are totally uppercase
(e.g., MPI_INIT), whereas C-compatible MPI routine names are
upper and lowercase (e.g., MPI_Init).
- The arguments to most C-compatible MPI functions are more strongly
typed than they are in Fortran, having specific C types such as
MPI_Comm and MPI_Datatype where Fortran has integers.
- The include files are different: in C, mpi.h, in
- The arguments to MPI_Init are different, so that a C program
can take advantage of command-line arguments.