Hi,

I'm trying to define a simple forward difference operator Δ to act on a function f(n). I have defined, in a number of ways, Δ(f(n)) = f(n+1) - f(n). This works fine but I want Maple to calculate powers of Δ. e.g Δ² (f(n))= f(n+2) - 2f(n+1) + f(n). As it stands, Maple returns (f(n+1) - f(n))² seemingly however I define the functions.
What am I doing wrong? Help much appreciated.

DJF