One quite general computation method, based on exponential growth of length, was studied by Newhouse and Pignataro. For piecewise monotone interval mappings, probably the simplest interesting dynamical systems, there is an effective computation that depends on being able to order finitely many forward images of critical points. I will be offering a possible rival computation: an algorithm based on kneading theory, which may not have the same degree of generality, but which would give a better entropy estimate much faster when it applies.