MPLRS(1) mplrs 7.2 MPLRS(1)

mplrs - Convert between representations of convex polyhedra (parallel version).

mpirun -np num_proc mplrs infile [outfile] [option...]

A polyhedron can be described by a list of inequalities (H-representation) or as by a list of its vertices and extreme rays (V-representation). lrs is a C program that converts a H-representation of a polyhedron to its V-representation, and vice versa.  These problems are known respectively at the vertex enumeration and convex hull problems.

The number of processors num_proc specified to mpirun should be 4 or higher Unlike lrs (1), mplrs does not support options after the end statement of the input file.

mplrs supports the following options.

-id <initial depth> [2] the depth of the original tree search to populate the job queue L
-maxc <maxcobases>[50 (*scale)] a producer stops and returns all subtrees that are not leaves to L after generating  maxc nodes   
-maxd <depth>[0] a producer returns all subtrees that are not leaves at depth maxd. Zero if not used
-lmin <int>[3] if job queue |L|<np*lmin then the maxd parameter is set for all producers
-lmax <int>[lmin] if job queue |L|>np*lmax then then maxc is replaced by maxc*scale
-scale <int>[100]used by lmax
-hist <file>store parallelization data in <file> for use by gnuplot, see below
-temp <prefix>[/tmp/] store a temporary file for each process. Should be specified if /tmp not writeable. Using " -temp  ./ " will write temporary files to the current directory
-freq <file> store frequency data in <file> for use by gnuplot, see below
-stop <stopfile> terminate mplrs if a file with name <stopfile> is created in the current directory
-checkp <checkpoint file> if mplrs is terminated by -stop or -time then it can be restarted using this <checkpoint file> and -restart
-restart <checkpoint file> restart mplrs using previously created <checkpoint file>. If used with -checkp file names should be different!
-time <seconds> terminate mplrs after <seconds> of elapsed time
-countonly don't output vertices/rays/facets, just count them
-maxbuf <n>[500] controls maximum size of worker output buffers
-stopafter <n> exit after approximately <n> cobases have been computed (no guarantee about how many vertices/rays/facets computed)
-redund perform redundancy check of input file (also see redund )
The parameters -hist and -freq give interesting information about the degree of parallelization.

Input file mp5.ine is run with 8 processors. The output file mp5.mplrs is in the distribution. This produced 378 subtrees that were enumerated in parallel using 6 producer cores,  1 core controlling the run and 1 core collecting the output.

      mai20% mpirun -np 8 mplrs mp5.ine mp5.mplrs
      *mplrs:lrslib v.6.0 2015.7.13(lrsgmp.h)8 processes
      *Copyright (C) 1995,2015, David Avis   avis@cs.mcgill.ca
      *Input taken from mp5.ine
      *Output written to: mp5.mplrs
      *Starting depth of 2 maxcobases=50 maxdepth=0 lmin=3 lmax=3 scale=100
      *Phase 1 time: 0 seconds.
      *Total number of jobs: 378, L became empty 4 times
      *Totals: vertices=32 rays=0 bases=9041 integer-vertices=16
      *Elapsed time: 1 seconds.
      2.285u 0.137s 0:01.86 129.5%    0+0k 0+9976io 36pf+0w

lrs(1), lrslib(1)

2020.7.28 July 2020