Scotch Brand 5.1.10 - Manual (Page 58)

such as floating point exceptions, which could not be properly handled by the
calling software.
7.3.2 Mapping strategy strings
At the time being, mapping methods only apply to graphs, as there is not yet a mesh
mapping tool in the Scotch package. Mapping strategies are made of methods,
with optional parameters enclosed between curly braces, and separated by commas,
in the form of method [{parameters}] . The currently available mapping methods
are the following.
m Multi-level method. The parameters of the multi-level method are listed be-
low.
asc=strat
Set the strategy that is used to refine the mappings obtained at ascending
levels of the uncoarsening phase by projection of the mappings computed
for coarser graphs. This strategy is not applied to the coarsest graph,
for which only the low strategy is used.
low=strat
Set the strategy that is used to compute the mapping of the coarsest
graph, at the lowest level of the coarsening process.
rat=rat
Set the threshold maximum coarsening ratio over which graphs are no
longer coarsened. The ratio of any given coarsening cannot be less that
0.5 (case of a perfect matching), and cannot be greater than 1.0. Coars-
ening stops when either the coarsening ratio is above the maximum coars-
ening ratio, or the graph has fewer vertices than the minimum number
of vertices allowed.
type=type
Set the type of matching that is used to coarsen the graphs. type is h for
heavy-edge matching, or s for scan (first-fit) matching.
vert=nbr
Set the threshold under which graphs are no longer coarsened. Coarsen-
ing stops when either the coarsening ratio is above the maximum coars-
ening ratio, or the graph would have fewer vertices than the minimum
number of vertices allowed. When the target architecture is a variable-
sized architecture, coarsening stops when the coarsened graph would have
less than nbr vertices. When the target architecture is a regular, fixed-
size, architecture, coarsening stops when each subdomain would have less
than nbr vertices, that is, when the size of the coarsened graph would
have less than nbr × domnnbr vertices, where domnnbr is the number of
vertices in the target architecture.
r Dual Recursive Bipartitioning mapping algorithm, as defined in section 3.1.3.
The parameters of the DRB mapping method are listed below.
job=tie
The tie flag defines how new jobs are stored in job pools.
t Tie job pools together. Subjobs are stored in same pool as their par-
ent job. This is the default behavior, as it proves the most efficient
in practice.
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