MPI_Init(3) Open MPI MPI_Init(3)NAMEMPI_Init - Initializes the MPI execution environment
SYNTAXC 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 erro‐
neous.
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++ 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.
See the MPI man page for a full list of MPI error codes.
SEE ALSO
MPI_Init_thread
MPI_Initialized
MPI_Finalize
1.7.4 Feb 04, 2014 MPI_Init(3)
