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()
- 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