What is perPlex

perPlex is a tool to verify the feasibility, optimality and integrality of a linear programming basis. Given a linear programming problem in .mps file format and a basis in .bas format, perPlex computes the primal and dual variables using rational arithmetic and determines if the basis is indeed feasible and optimal. Integrality of integer variables can also be verified. The exact value of objective function is printed.

Where does is run?

perPlex is a command line program written in plain C and released under GNU GPL. It needs the GNU GMP library and the zlib library. perPlex has been tested to compile under Linux/Intel, Solaris, Tru64 and AIX. Probably it will compile and run wherever a decent OS and C compiler is available.


The latest Version is 1.01. Go to the Download.
Differences to the older versions are in the Changelog.

Files with LP's in .mps-format, an associated optimal basis in .bas-format and a perPlex solution file are in the data directory.


If you find one (shouldn't be to difficult), it would be nice if you send a description or even better a working fix with a runnable example .mps.gz and .bas.gz file to


You need an LP solver that can write .bas files to verify. I have only tried CPLEX for this. The next version of SoPlex (to be available sometime this year) will do it also.


Related sites

Netlib-LP repository
MIPLIB-IP repository
GNU multiple precision arithmetic library (GMP)
zlib - a massively spiffy yet delicately unobtrusive compression library

Interesting sites

Zimpl Modeling Language
SoPlex LP Solver
Decision Tree for Optimization Software
Mathematical Programming GlossaryŠ by Harvey J. Greenberg
INFORMS OR/MS Resource Collection
NEOS Server for Optimization

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Last Update $Date: 2005/03/03 21:30:40 $ by Thorsten Koch
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