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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 pro-
     duced  by	option -v) is sent to file lfile. When file names are not speci-
     fied, 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 di-
     rectly  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 speci-
	    fies, 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 re-
	    build 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)

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