MPI_Bcast(3OpenMPI)													       MPI_Bcast(3OpenMPI)

NAME

       MPI_Bcast - Broadcasts a message from the process with rank root to all other processes of the group.

SYNTAX

C Syntax
       #include <mpi.h>
       int MPI_Bcast(void *buffer, int count, MPI_Datatype datatype,
	    int root, MPI_Comm comm)

Fortran Syntax
       INCLUDE 'mpif.h'
       MPI_BCAST(BUFFER, COUNT, DATATYPE, ROOT, COMM, IERROR)
	    <type>    BUFFER(*)
	    INTEGER   COUNT, DATATYPE, ROOT, COMM, IERROR

C++ Syntax
       #include <mpi.h>
       void MPI::Comm::Bcast(void* buffer, int count,
	    const MPI::Datatype& datatype, int root) const = 0

INPUT
/OUTPUT PARAMETERS
       buffer	 Starting address of buffer (choice).

       count	 Number of entries in buffer (integer).

       datatype  Data type of buffer (handle).

       root	 Rank of broadcast root (integer).

       comm	 Communicator (handle).

OUTPUT PARAMETER

       IERROR	 Fortran only: Error status (integer).

DESCRIPTION

       MPI_Bcast  broadcasts a message from the process with rank root to all processes of the group, itself included. It is called by all members
       of group using the same arguments for comm, root. On return, the contents of root's communication buffer has been copied to all processes.

       General, derived datatypes are allowed for datatype. The type signature of count, datatype on any process must be equal to the type  signa-
       ture  of count, datatype at the root. This implies that the amount of data sent must be equal to the amount received, pairwise between each
       process and the root. MPI_Bcast and all other data-movement collective routines make this restriction. Distinct type  maps  between  sender
       and receiver are still allowed.

       Example: Broadcast 100 ints from process 0 to every process in the group.
	   MPI_Comm comm;
	   int array[100];
	   int root=0;
	   ...
	   MPI_Bcast( array, 100, MPI_INT, root, comm);

       As in many of our sample code fragments, we assume that some of the variables (such as comm in the example above) have been assigned appro-
       priate values.

       WHEN COMMUNICATOR IS AN INTER-COMMUNICATOR

       When the communicator is an inter-communicator, the root process in the first group broadcasts data to all  the	processes  in  the  second
       group.	The  first group defines the root process.  That process uses MPI_ROOT as the value of its root argument.  The remaining processes
       use MPI_PROC_NULL as the value of their root argument.  All processes in the second group use the rank of that root process  in	the  first
       group  as the value of their root argument.   The receive buffer arguments of the processes in the second group must be consistent with the
       send buffer argument of the root process in the first group.

NOTES

       This function does not support the in-place option.

ERRORS

       Almost all MPI routines return an error value; C routines as the value of the function and Fortran routines in the last argument. C++ func-
       tions  do not return errors. If the default error handler is set to MPI::ERRORS_THROW_EXCEPTIONS, then on error the C++ exception mechanism
       will be used to throw an MPI:Exception object.

       Before the error value is returned, the current MPI error handler is called. By default, this error handler aborts the MPI job, except  for
       I/O  function  errors. The error handler may be changed with MPI_Comm_set_errhandler; the predefined error handler MPI_ERRORS_RETURN may be
       used to cause error values to be returned. Note that MPI does not guarantee that an MPI program can continue past an error.

Open MPI 1.2							  September 2006					       MPI_Bcast(3OpenMPI)