PHClab: A MATLAB/Octave Interface to PHCpack. PHCpack is a software package for Polynomial Homotopy Continuation, to numerically solve systems of polynomial equations. The executable program “phc” produced by PHCpack has several options (the most popular one “-b” offers a blackbox solver) and is menu driven. PHClab is a collection of scripts which call phc from within a MATLAB or Octave session. It provides an interface to the blackbox solver for finding isolated solutions. We executed the PHClab functions on our cluster computer using the MPI ToolBox (MPITB) for Octave to solve a list of polynomial systems. PHClab also interfaces to the numerical irreducible decomposition, giving access to the tools to represent, factor, and intersect positive dimensional solution sets.