Parameter definitions

The application programmer supplies PARAMETER definitions for the following:

• The dimensions of the (N-dimensional) grid.
• The width of the ghost boundary. (This width cannot be larger than the size of a local section.)
• The dimensions of the process grid (i.e., how many grid processes are to be used).

This is done by modifying the archetype-supplied INCLUDE file mesh_uparms.h; see comments in the file for additional information.

The archetype uses these definitions to declare additional PARAMETERs:

• The dimensions of a local section.
• Index ranges for a local section, including ghost boundaries.

These PARAMETERs should be used to work with grid-based data -- for declarations, loop bounds, etc. See comments in the INCLUDE file mesh_parms.h for more information.

Example

For example, to distribute a grid of dimensions 1000 by 1000 by 1000 over a process grid of dimensions 2 by 2 by 2 (8 grid processes in all), for a computation in which new values for grid variables require values at nearest-neighbor points only, the application programmer would define:

• Grid dimensions NX=1000, NY=1000, and NZ=1000.
• Ghost boundary NGHOST=1.
• Process grid dimensions XPROCS=2, YPROCS=2, and ZPROCS=2.