Question

Put the following blocks of pseudocode in the correct order to make the main function for our program.

a. Initialize the MPI program.
A) Rank = MPI_Commᵣank(MPI_COMM_WORLD, &rank);
B) MPI_Init(&argc, &argv);
C) MPI_Finalize();

Answer 1

The correct order to initialize an MPI program is to first call B) MPI_Init, then A) MPI_Comm_rank, and finally C) MPI_Finalize. This sequence ensures proper setup and termination of the MPI environment.

Step-by-step explanation:

The correct order for the provided blocks of pseudocode in creating the main function of an MPI (Message Passing Interface) program is as follows:

1. B) MPI_Init(&argc, &argv); - This initializes the MPI environment and should be the first call in any MPI program.
2. A) Rank = MPI_Comm_rank(MPI_COMM_WORLD, &rank); - After initialization, this determines the rank of the calling process in the communicator. It is important to call this after MPI_Init so that the MPI environment is set up properly.
3. C) MPI_Finalize(); - This terminates the MPI environment and should be the last call in any MPI program. It cleans up the MPI state.

Following this order is crucial for the proper functioning of an MPI program as it provides the framework for any parallel computation involving multiple processes.