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>

                                                23 November 2019                                        dgord(1)