(3M) Calculator User Manual

Since its main purpose is to provide order ings that exhibit high concurrency
for parallel block factorization, it comprises a nested dissection method [17],
but classical [39] and state-of-the-art [1, 47] minimum degree algorithms are
implemented as well. Ordering methods are used to define ordering strateg ie s
by means of selection, grouping, and condition operators.
The -o optio n allows the user to define the ordering strategy. The -c option
allows the user to set preferences on the behavior of the ordering strategy
which is used by default.
Options
Since the program is devoted to experimental studies, it has many optional
parameters, used to test various execution modes . Values set by default will
give best results in most cases.
-cflags
Tune the default ordering strategy according to the given preference flags.
Some of these flags are antagonistic, while others can be combined. See
Section 7.3.1 for more information. The resulting strategy string can be
displayed by means of the -vs option.
b Enforce load balance as much as possible.
q Privilege quality over speed. This is the default behavior.
s Privilege sp e ed over quality.
t Use only safe methods in the strategy.
-h Display the program synopsis.
-moutput
mapping file
Write to output mapping file the mapping of mesh node vertices to col-
umn blocks. All of the separators and leaves produced by the nested
dissection method are considered as distinct column blocks, which may
be in turn split by the ordering methods that are applied to them. Dis-
tinct integer number s are associated with each of the column blocks, such
that the number of a block is always g reater than the ones of its prede-
cessors in the elimination pro c e ss, that is, its leaves in the elimination
tree. The structure of mapping files is given in section 5.5.
When the coordinates of the node vertices are available, the mapping
file may be proc e ssed by program gout, along with the graph structure
that can b e created from the source mesh file by means of the gmk
msh program, to display the node vertex separ ators and super variable
amalgamatio ns that have been computed.
-ostrat
Apply ordering strategy strat. The format of ordering strategies is defined
in section 7.3.4.
-toutput
tree file
Write to ou tput tree file the structure of the separator tree. The data
that is written resembles much the o ne of a mapping file: after a first
line that conta ins the number of lines to follow, there are that many
lines of mapping pairs, which associate a n integer number with every
node vertex index. This integer number is the number of the column
block which is the parent of the column block to which the node vertex
belongs, or −1 if the column block to which the node ve rtex belongs is
45