Eigency is a Cython interface between Numpy arrays and Matrix/Array objects
from the Eigen C++ library. It is intended to simplify the process of writing
C++ extensions using the Eigen library. Eigency is designed to reuse the
underlying storage of the arrays when passing data back and forth, and will
thus avoid making unnecessary copies whenever possible. Only in cases where
copies are explicitly requested by your C++ code will they be made
(see example below)

Below is a description of a range of common usage scenarios. A full working
example of both setup and these different use cases is available in the test
directory distributed with the this package.