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dgord(1)                    PT-Scotch user's manual                   dgord(1)

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
       -c?opt 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.

       -m?mfile
              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.

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

       -r?pnum
              Set root process for centralized files (default is 0).

       -t?tfile
              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.

       -v?verb
              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

SEE ALSO
       dgtst(1), dgscat(1), gmk_hy(1), gord(1).

       PT-Scotch user's manual.

AUTHOR
       Francois Pellegrini <francois.pellegrini@labri.fr>

                               February 14, 2011                      dgord(1)