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').

  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

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

  PT-Scotch user's manual.

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