broadcast-scatter

Broadcast and scatter

Write a simple program using send and receive calls to implement broadcast and scatter operations. We will see later in the course how to do this using MPI’s collective operations, but it is useful to implement them by hand as they illustrate how to communicate all or part of an array of data using point-to-point operations.

1. Create an integer array of size N (e.g. N=12) and initialize it as follows:
   • rank 0: i (i=1,12)
   • other ranks: -1
2. Print out the initial values in all the processes
3. Implement broadcast: rank 0 sends the contents of the entire array to other ranks. Print out the final values in all the processes.
4. Implement scatter: imagine that the array is divided into N / P sections (P=number of processes), and rank 0 sends different section to other ranks, so that rank i receives the ith section. Print out the final values in all the processes.

You may start from scratch or use skeleton.cpp (or skeleton.F90 for Fortran) as a starting point.