RunDec: a Mathematica package for running and decoupling of the strong coupling and quark masses

In this paper the formulae are collected which are needed for the computati on of the strong coupling constant and quark masses at different energy sca les and for different number of active flavors. All equations contain the s tate-of-the-art QCD corrections up to three- and sometimes even four-loop o rder. For the practical implementation Mathematica is used and a package co ntaining useful procedures is provided. (C) 2000 Elsevier Science B.V. All rights reserved.