Mutual recursion

A form of recursion where two mathematical or computational functions are defined in terms of each other.

For instance, consider two functions A(x) and B(x) defined as follows:

 A(x, x<=1) = 1

 A(x where x>1) = B(x + 2)

 B(x) = A(x - 3) + 4

It is not obvious from inspection under what circumstances calling either of these functions will ever reach the non-recursive case

and thus return an answer, and this often holds true even for non-contrived examples. Therefore, is computer programming,

mutually recursive functions are generally regarded as bad style.