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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  or-
       dering  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  com-
       pressed	file  extension, such as in 'brol.grf.bz2' or '-.gz'. The com-
       pression	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 op-
	      tions 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 spec-
	      ifies,  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 al-
	      lows 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 sequen-
       tial 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	 frag-
       ments).

	   $ 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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