Big-Theta Notation
Big theta notation is a little more complicated, the Big-Theta notation covers both the worst and best-case scenarios that an algorithm might have relative to its input (n). So it essentially is a combination of both Big-Oh Notation and Big Omega Notation. Since we are trying to cover two cases, the calculation is quite different:
# Calculating Big Theta
A function $f(n)$ is said to be $\Theta(g(n))$ if there exists constants $c’ > 0$, $c’’ > 0$ and $n_0 > 1$ such that:
$$\forall n (n > n_0 \implies c’g(n) \leq f(n) \leq c’‘g(n))$$