Documentation: Fix examples and clarify Eigen API notes libeigen/eigen!2652 Closes #998, #2142, #301, #1822, #1959, #805, #462, #308, #2146, #1335, #634, #81, and #46
Eigen is a C++ template library for linear algebra: matrices, vectors, numerical solvers, and related algorithms.
For more information go to http://eigen.tuxfamily.org/ or https://libeigen.gitlab.io.
For pull request, bug reports, and feature requests, go to https://gitlab.com/libeigen/eigen.