Eigen  3.4.90 (git rev 67eeba6e720c5745abc77ae6c92ce0a44aa7b7ae)
#include <Eigen/MetisSupport>

This module defines an interface to the METIS reordering package (http://glaros.dtc.umn.edu/gkhome/views/metis). It can be used just as any other built-in method as explained in here.