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

SEE ALSO

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

       PT-Scotch user's manual.

AUTHOR

       Francois Pellegrini <francois.pellegrini@labri.fr>

                                                 August 03, 2010                                        dgord(1)