We compare and contrast concave and convex lenses by drawing ray diagrams.

This paper examines properties and interrelations of several concepts of generalized concavity. It shows that the class of functions that are both 'generalized concave' and 'generalized convex' is ...

In a previous paper, we showed that gradient maps of exponentially concave functions provide solutions to a Monge–Kantorovich optimal transport problem and give a better gradient approximation than ...