[MPI] Collective communication - MPI_Bcast

· One to all : MPI_Bcast, MPI_Scater

· All to one : MPI_Reduce, MPI_Gather

· All to all : MPI_Alltoall

- MPI_Bcast : Broadcasts a message from "root" process to all other process in the same communicator.

- C/C++ : MPI_Bcast( array, 100, MPI_INT, 3, comm); 

- Fortran : call MPI_Bcast( array, 100, MPI_INTEGER, 3, comm,ierr) 

- Example Source Code

program hello
    use mpi
    integer :: f(10)
    integer :: status(MPI_STATUS_SIZE)
    integer :: rank, src=0, dest=1, ierr, i

    call mpi_init(ierr) 
    call MPI_Comm_rank( MPI_COMM_WORLD, rank,ierr);
    !array preparation from src processor
    if (rank == src) then 
        do i = 1, 10
            f(i) = f(i) + i
        end do
    end if

    !broad cast integer array
    call MPI_Bcast(f, 10, MPI_INT, src, MPI_COMM_WORLD, ierr)
    print *, f
    call mpi_finalize(ierr)
end program hello

-Output
C>>mpiexec -n 3 mpibcast.exe
           1           2           3           4           5           6
           1           2           3           4           5           6
           7           8           9          10
           7           8           9          10
           1           2           3           4           5           6
           7           8           9          10