pscotch_dgord(1) compute sparse matrix orderings in parallel


pscotch_dgord [options] [gfile] [ofile] [lfile]


The pscotch_dgord program computes, in a parallel way, an ordering of a 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', on input only).

pscotch_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.


Display some help.
Save column block mapping data to file mfile.
Use distributed ordering strategy strat (see PT-Scotch user's manual for more information).
Set root process for centralized files (default is 0).
Save partitioning tree data to file tfile.
Display program version and copyright.
Set verbose mode to verb. It is a set of one of more characters which can be:
strategy information.
timing information.


Run pscotch_dgord on 5 processing elements to reorder matrix graph brol.grf and save the resulting ordering to file brol.ord.

      $ mpirun -np 5 pscotch_dgord brol.grf brol.ord
Run pscotch_dgord on 5 processing elements to reorder the distributed matrix stored on graph fragment files brol5-0.grf to brol5-4.grf, 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 pscotch_dgord brol%p-%r.grf brol.ord


Francois Pellegrini <[email protected]>