pqzschur and percomplex.f is software by Daniel Kressner 
daniel.kressner@epfl.ch

This directory additionally contains percomplex.F, which is an 
adaption of percomplex.f to 64 bit systems by Hannes Uecker. 
This adaption is very ad hoc, i.e., it works (on Linux Mint 17, 
with Matlab 2013a), but it may not follow default procedures for 
such adaptions, see, e.g., 
de.mathworks.com/help/matlab/matlab_external/upgrading-mex-files-to-use-64-bit-api.html

Essentially, I simply replaced hard-coded parameters such as "1" in 
function calls by variables "hu1" (where hu1=1 is of type mwpointer, 
which seems to be the most general setting available). 

To use pqzschur.m (and hence floqps in pde2path), proceed as follows: 

* on 32-bit systems, in the matlab prompt call 
  mex percomplex.f -lmwlapack -lmwblas
  You may have to call mex -setup beforehand. 

* Similarly, on 64-bit systems, call 
  mex percomplex.F -lmwlapack -lmwblas

* test percomplex (and pqzschur.m) via pstest.m 