2.6. What arguments are needed for the routines?

The input argument lists closely match the list for C and Fortran MPI routines. The difference between the Python call and C/Fortran calls is that values returned via assignment. For example, in C we would do a message receive into buffer of count integers from process source using the syntax:

MPI_Recv(&buffer, count, MPI_INT, source, tag, MPI_COMM_WORLD, &status);

In Python this would be:

buffer=mpi.mpi_recv(count, mpi.MPI_INT, source, tag, mpi.MPI_COMM_WORLD)

After these calls buffer would contain the data from the remote process. Status is returned using a special call

status=mpi_status()

After this call status is an array that contains, the source of the message, the tag, and the error code.