@mrocklin : Got your point. I was clear about the fact that equalities like `correlation(X, X*X) == 7*sqrt(11505)/767` should not be present in the examples but thought that it would be ok to put them in tests since the process is automated. Now I realize that not only does it increase test time (as evident from my 2 latest Travis tests not completing in 50min) but also that it brings no value for another programmer who might have to intervene with the code in future. Thanks for refactoring me.