- Bounded: A mathematical object (such as a set or function) is said to bounded if it possesses a bound, i.e., a value which all members of the set, functions, etc., are less than.
- Ck function: Sometimes continuously differentiable functions are said to be of class C1. A function is of class C2 if the first and second derivative of the function both exist and are continuous. More generally, a function is said to be of class Ck if the first k derivatives f′(x), f″(x), …, f(k)(x) all exist and are continuous. If derivatives f(n) exist for all positive integers n, the function is smooth or equivalently, of class C∞.