Single source of truth for the slab/block partition: the number of global
cells owned by rank_id (0-based) when n_global cells are split across
n_ranks. floor(n_global/n_ranks) per rank, with the remainder distributed
one extra cell each to the first mod(n_global,n_ranks) ranks. Pure — used
by decompose(), the gather/scatter count builders, and the 2D axis split so
the partition arithmetic exists in exactly one place.
| Type | Intent | Optional | Attributes | Name | ||
|---|---|---|---|---|---|---|
| integer, | intent(in) | :: | n_global | |||
| integer, | intent(in) | :: | n_ranks | |||
| integer, | intent(in) | :: | rank_id |