dgord - Online in the Cloud

This is the command dgord that can be run in the OnWorks free hosting provider using one of our multiple free online workstations such as Ubuntu Online, Fedora Online, Windows online emulator or MAC OS online emulator

PROGRAM:

NAME


dgord - compute sparse matrix orderings of graphs in parallel

SYNOPSIS


dgord [options] [gfile] [ofile] [lfile]

DESCRIPTION


The dgord program computes, in a parallel way, an ordering of a Scotch source graph
representing the pattern of some symmetric sparse matrix.

Source graph file gfile is either a centralized graph file, or a set of files representing
fragments of a distributed graph. The resulting ordering is stored in file ofile. Eventual
logging information (such as the one produced by option -v) is sent to file lfile. When
file names are not specified, data is read from standard input and written to standard
output. Standard streams can also be explicitely represented by a dash '-'.

When the proper libraries have been included at compile time, dgord can directly handle
compressed graphs, both as input and output. A stream is treated as compressed whenever
its name is postfixed with a compressed file extension, such as in 'brol.grf.bz2' or
'-.gz'. The compression formats which can be supported are the bzip2 format ('.bz2'), the
gzip format ('.gz'), and the lzma format ('.lzma', on input only).

dgord bases on implementations of the MPI interface to spread work across the processing
elements. It is therefore not likely to be run directly, but instead through some launcher
command such as mpirun.

OPTIONS


-copt Choose default ordering strategy according to one or several options among:

b enforce load balance as much as possible.

q privilege quality over speed (default).

s privilege speed over quality.

t enforce safety.

x enforce scalability.

-h Display some help.

-mmfile
Save column block mapping data to file mfile. Mapping data specifies, for each
vertex, the index of the column block to which this vertex belongs.

-ostrat
Use parallel graph ordering strategy strat (see PT-Scotch user's manual for more
information).

-rpnum Set root process for centralized files (default is 0).

-ttfile
Save partitioning tree data to file tfile. Partitioning tree data specifies, for
each vertex, the index of the first vertex of the parent block of the block to
which the vertex belongs. Altogether with the mapping data provided in file mfile,
it allows one to rebuild the separator tree of the nested dissection process.

-V Display program version and copyright.

-vverb Set verbose mode to verb. It is a set of one of more characters which can be:

s strategy information.

t timing information.

EXAMPLES


Run dgord on 5 processing elements to reorder matrix graph brol.grf and save the resulting
ordering to file brol.ord, using the default sequential graph ordering strategy:

$ mpirun -np 5 dgord brol.grf brol.ord

Run dgord on 5 processing elements to reorder the distributed matrix stored on graph
fragment files brol5-0.dgr to brol5-4.dgr, and save the resulting ordering to file
brol.ord (see dgscat(1) for an explanation of the '%p' and '%r' sequences in names of
distributed graph fragments).

$ mpirun -np 5 dgord brol%p-%r.dgr brol.ord

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