3 Box partition

Each partition is a rectangular region of the global domain, described by the global offset of its upper left corner, and its local extents in the X and Y dimensions. The global extent in the X dimension must also be given. In this case, we have ig_paral(1:5):

• ig_paral(1) = 2 (indicates a Box partition)
• ig_paral(2) = the upper left corner global offset
• ig_paral(3) = the local extent in x
• ig_paral(4) = the local extent in y
• ig_paral(5) = the global extent in x.

Figure 2.4 illustrates a Box partition over 3 processes.

Figure 2.4: Box partition. It is assumed here that the global index starts at 0 in the upper left corner.