The Lipschitz Constant of a Nonarchimedean Rational Function

Let K be a complete, algebraically closed nonarchimedean valued field, and let f(z) be a non-constant rational function in K(z). We provide explicit bounds for the Lipschitz constant of f(z) acting on the Berkovich projective line, relative to the Favre/Rivera-Letelier d(x,y)-metric, and for the Lipschitz constant of f(z) acting on classical points in the projective line, relative to the spherical metric.