Are there functions which takes itself as an argument? Like: $f(x,f(x_{n\pm1}))$
A functions which value at a given point depends on its value on the next,or previous intake value. Or: $f(x,f(x))$.
A function which value at a given point depends on itself at that given point. This seems like nonsense because it should be: $f(x,f(x,f(x,f(x....))$