In mathematics, a fixed point (sometimes shortened to fixpoint, also known as an invariant point) of a function is an element of the function's domain that is mapped to itself by the function. That is to say, c is a fixed point of the function f(x) if and only if f(c) = c. This means f(f(...f(c)...)) = fⁿ(c) = c, an important terminating consideration when recursively computing f. A set of fixed points is sometimes called a fixed set.