this code efficiently approximately solves the quadratic assignment problem.
see our manuscript
Fast Inexact Graph Matching with Applications in Statistical Connectomics
Joshua T. Vogelstein, John M. Conroy, Louis J. Podrazik, Steven G. Kratzer, Donniell E. Fishkind, R. Jacob Vogelstein, Carey E. Priebe
for details.  it is on the arxiv here:
http://arxiv.org/abs/1112.5507

run bench_qap(20) for a demo
