“Numerical Methods for Special Functions” by Gil, Seguar and Temme is a collection of methods and approaches for finding the most efficient and accurate ways of computing values of functions that have no general definition. “Numerical Methods for Special Functions” might appear at first glance to be a boring and perhaps dry subject for non-mathematicians, and indeed it is a little difficult to approach without being an expert in the area, but if you do find yourself in need of some hints for the best implementations available, this book might be a life saver.