  Metrized graphs are nonarchimedean analogues of Riemann surfaces, and
Arakelov-Green functions on these graphs are of fundamental importance for some
aspects of arithmetic geometry. In the present paper, we give an explicit
formula for an admissible Arakelov-Green function on a metrized graph,
extending Cinkir's formula for the canonical Arakelov-Green function. Based on
our formula, we present and implement an algorithm in the computer algebra
system SageMath for explicitly computing such functions. We illustrate our
algorithm with computational examples.
