http://eigen.tuxfamily.org/dox/unsupported/index.html
Would you be willing to take contributions allowing users to use unsupported code from Eigen?
A lot of the stuff inside of the unsupported modules seems to be well-tested, user-supplied code, as well
as being very useful. For example, the unsupported modules define things such as the Kronecker
Product and FFT.
I would put these in Data.Eigen.Unsupported.X or something. I am willing to start work on such a
contribution(s).