Starting and Terminating the MPI Library

• MPI_Init is called prior to any calls to other MPI routines. Its purpose is to initialize the MPI environment. Calling MPI_Init more than once during the execution of a program will lead to an error.
• MPI_Finalize is called at the end of the computation, and it performs various clean-up tasks to terminate the MPI environment. No MPI calls may be performed after MPI_Finalize has been called, not even MPI_Init.
• Upon successful execution, MPI_Init and MPI_Finalize return MPI_SUCCESS; otherwise they return an implementation-defined error code.