Ackermann’s Function
May 25, 2012
In the 1920s, Wilhelm Ackermann demonstrated a computable function that was not primitive-recursive, settling an important argument in the run-up to the theory of computation. There are several versions of his function, of which the most common is
defined over non-negative integers m and n. The function grows very rapidly, even for very small inputs; as an example, A(4,2) is an integer of about 20,000 digits.
Your task is to implement Ackermann’s function. When you are finished, you are welcome to read or run a suggested solution, or to post your own solution or discuss the exercise in the comments below.
Programming Praxis 