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

       dgmap, dgpart - compute static mappings and partitions in parallel

       dgmap [options] [gfile] [tfile] [mfile] [lfile]

       dgpart [options]	[nparts/pwght] [gfile] [mfile] [lfile]

       The  dgmap  program  computes, in a parallel way, a static mapping of a
       source graph onto a target graph.

       The dgpart program is a simplified interface to dgmap,  which  performs
       graph partitioning instead of static mapping. Consequently, the desired
       number of parts has to be provided, in lieu of the target architecture.
       When  using the program for graph clustering, the number	of parts turns
       into maximum cluster weight.

       The -b and -c options allow the user to set preferences on the behavior
       of  the mapping strategy	which is used by default. The -m option	allows
       the user	to define a custom mapping strategy.

       The -q option turns the programs	into  graph  clustering	 programs.  In
       this case, dgmap	only accepts variable-sized target architectures.

       Source graph file gfile is either a centralized graph file, or a	set of
       files representing fragments of a distributed  graph.  For  dgmap,  the
       target  architecture  file tfile	describes either algorithmically-coded
       topologies such as meshes and hypercubes, or decomposition-defined  ar-
       chitectures created by means of the amk_grf(1) program. See gmap(1) for
       a description of	target architectures. The resulting mapping is	stored
       in  file	 mfile.	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. Stan-
       dard streams can	also be	explicitely represented	by a dash '-'.

       When the	proper libraries have been included at compile time, dgmap and
       dgpart 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 in-
       put only).

       dgmap and dgpart	base on	implementations	of the MPI interface to	spread
       work  across  the processing elements. They are therefore not likely to
       be run directly,	but instead through  some  launcher  command  such  as

       -bval  Set  maximum  load  imbalance  ratio  for	 graph partitioning or
	      static mapping. When programs are	used as	clustering tools, this
	      parameter	 sets  the  maximum load imbalance ratio for recursive
	      bipartitions. Exclusive with the -m option.

       -copt  Choose default mapping 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.

	      It is exclusive with the -m option.

	      -h     Display some help.

		     Use parallel mapping strategy strat (see PT-Scotch	user's
		     manual for	more information).

	      -q     (for dgpart)

		     (for dgmap) Use the programs as  graph  clustering	 tools
		     instead  of  static  mapping or graph partitioning	tools.
		     For dgpart, the number of parts will become  the  maximum
		     cluster  weight.  For  dgmap, this	number pwght has to be
		     passed after the option.

	      -rpnum Set root process for centralized files (default is	0).

	      -V     Display program version and copyright.

	      -vverb Set verbose mode to verb. It is a	set  of	 one  of  more
		     characters	which can be:

		     m	    mapping information.

		     s	    strategy information.

		     t	    timing information.

       At  the time being (version 5.1), dgmap cannot compute full static map-
       pings as	gmap(1)	does, but only partitions (that	is, mappings onto  un-
       weighted	 or weighted complete graphs). Target architectures other than
       the 'cmplt' and 'wcmplt'	ones will lead to an error message.

       Run dgpart on 5 processing elements to compute a	partition into 7 parts
       of graph	brol.grf and save the resulting	ordering to file

	   $ mpirun -np	5 dgpart 7 brol.grf

       Run  dgpart on 5	processing elements to partition into 7	parts the dis-
       tributed	 graph	stored	on  graph  fragment   files   brol5-0.dgr   to
       brol5-4.dgr,  and  save	the  resulting	mapping	 to file (see
       dgscat(1) for an	explanation of the '%p'	and '%r' sequences in names of
       distributed graph fragments).

	   $ mpirun -np	5 dgpart 7 brol%p-%r.dgr

       dgtst(1), dgscat(1), amk_grf(1),	acpl(1), gmap(1), gmtst(1).

       PT-Scotch user's	manual.

       Francois	Pellegrini <>

			      September	01, 2011		      dgmap(1)


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