Algorithmic definition of means acting on positive numbers and operators
  Means are used in several applications from electronic engeneering to information theory, however there is no general theorem on how to extend a given M(x, y) mean function to multiple variable forms. In this article we would like to present a theorem, which gives one possible solution for this problem, for every M(x, y) mean function, acting on positive numbers and operators. 
Miklos Palfia