Big oh notation (O): The upper bound for the function 'f' is given by the big oh notation (O). Considering 'g' to be a function from the non-negative integers to the positive real numbers, we describe O(g) as the set of function f  such that  for some real constant c>0 and some non negative integers constant n0 , f(n) ≤ cg(n) for all n≥n0. Mathematically, O(g(n))= {f(n): there exists positive constants like that 0≤f f(n) ≤ cg(n) for all n, n≥n0} , we say "f is oh of g".