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dgord(1)		    PT-Scotch user's manual		      dgord(1)

       dgord - compute sparse matrix orderings of graphs in parallel

       dgord [options] [gfile] [ofile] [lfile]

       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.

       -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.

	      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.

	      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).

	      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

       -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.

       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-

	   $ mpirun -np	5 dgord	brol%p-%r.dgr brol.ord

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

       PT-Scotch user's	manual.

       Francois	Pellegrini <>

			       February	14, 2011		      dgord(1)


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