TOPIC: Domain Decomposition Technique & Related Communication
GOAL:  Jacobi Iteration of a 2D Poisson Problem
CODE:  jacobi/. 

We will first finish the previous task (parallel search algorithm).

We will start considering the parallel techniques which are used for
implementing a solution to a 2D poisson equation by means of
finite-differences on a Cartesian mesh. We will go step by step. The
first task is to decompose the data in 1 direction such that it is as
evenly as possible distributed. We compute pointers to the global
array indices for each processor. This feature will make the final
code much simpler to understand and maintain.

Tasks 2 & 3 will be addressed in the following session.