Landau notation | o | O-notation | O-symbol
Let n be an integer variable which tends to infinity and let x be a continuous variable tending to some limit. Also, let ϕ(n) or ϕ(x) be a positive function and f(n) or f(x) any function. Then the symbols O(x) (sometimes called "big-O") and o(x) (sometimes called "little-o") are known as the Landau symbols and defined as follows. 1.f = O(ϕ) means that left bracketing bar f right bracketing bar 0 (Hardy and Wright 1979, pp. 7-8).