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
USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_INIT(IERROR)
INTEGER IERROR
Fortran 2008 Syntax
USE mpi_f08
MPI_Init(ierror)
INTEGER, OPTIONAL, INTENT(OUT) :: 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 most other MPI
routines are called. There are a small number of exceptions, such as
MPI_Initialized and MPI_Finalized. 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++ 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
MPI_Finalized
4.1.2 Nov 24, 2021 MPI_Init(3)
Generated by dwww version 1.14 on Fri Jan 24 14:04:54 CET 2025.