  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.
