Initializes the MPI execution environment. This function must be called
in every MPI program, must be called before any other MPI functions
and must be called only once in an MPI program. For C programs, MPI_Init
may be used to pass the command line arguments to all processes,
although this is not required by the standard and is implementation
dependent.
MPI_Init (&argc,&argv)
MPI_INIT (ierr)
MPI_Comm_size
Returns the total number of MPI processes in the specified
communicator, such as MPI_COMM_WORLD. If the communicator is
MPI_COMM_WORLD, then it represents the number of MPI tasks
available to your application.
Returns the rank of the calling MPI process within the specified communicator.
Initially, each process will be assigned a unique integer rank
between 0 and number of tasks - 1 within the communicator
MPI_COMM_WORLD. This rank is often referred to as a task ID.
If a process becomes associated with other communicators, it will have
a unique rank within each of these as well.
Basic blocking send operation. Routine returns only after the
application buffer in the sending task is free for reuse. Note that
this routine may be implemented differently on different systems. The
MPI standard permits the use of a system buffer but does not require it.
Some implementations may actually use a synchronous send (discussed
below) to implement the basic blocking send.
Terminates the MPI execution environment. This function should be
the last MPI routine called in every MPI program - no other MPI
routines may be called after it.