MPI_Init(3)                        Open MPI                        MPI_Init(3)



NAME
       MPI_Init - Initializes the MPI execution environment


SYNTAX
C Syntax
       #include <mpi.h>
       int MPI_Init(int *argc, char ***argv)


Fortran Syntax
       INCLUDE 'mpif.h'
       MPI_INIT(IERROR)
            INTEGER   IERROR


C++ Syntax
       #include <mpi.h>
       void MPI::Init(int& argc, char**& argv)
       void MPI::Init()


INPUT PARAMETERS
       argc      C/C++ only: Pointer to the number of arguments.

       argv      C/C++ only: Argument vector.


OUTPUT PARAMETER
       IERROR    Fortran only: Error status (integer).


DESCRIPTION
       This routine, or MPI_Init_thread, must be called before any other MPI
       routine (apart from MPI_Initialized) is called. MPI can be initialized
       at most once; subsequent calls to MPI_Init or MPI_Init_thread are
       erroneous.

       All MPI programs must contain a call to MPI_Init or MPI_Init_thread.
       Open MPI accepts the C/C++ argc and argv arguments to main, but neither
       modifies, interprets, nor distributes them:

            {
                 /* declare variables */
                 MPI_Init(&argc, &argv);
                 /* parse arguments */
                 /* main program */
                 MPI_Finalize();
            }


NOTES
       The Fortran version does not have provisions for argc and argv and
       takes only IERROR.

       The MPI Standard does not say what a program can do before an MPI_Init
       or after an MPI_Finalize. In the Open MPI implementation, it should do
       as little as possible. In particular, avoid anything that changes the
       external state of the program, such as opening files, reading standard
       input, or writing to standard output.


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++
       functions 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.

       See the MPI man page for a full list of MPI error codes.


SEE ALSO
       MPI_Init_thread
       MPI_Initialized
       MPI_Finalize




1.4.1                            Jan 14, 2010                      MPI_Init(3)
