We like mechanical calculators like slide rules, but we have to admit that we had not heard of the Ott Derivimeter that [Chris Staecker] shows us in a recent video. As the name implies, the ...

Let f be an analytic and univalent function on a simply connected domain D, and let λD be the hyperbolic metric on D. We prove the sharp inequality $\left| {\frac{{{f^n}\left( w \right)}}{{f\left( w ...