A complex valued function defined and analytic in the entire complex plane is called an entire function or an integral function. In other words, in the extended complex plane, it can have a singularity only at infinity. If f is an entire function different from a polynomial and M(r, f) [or M(r) when there is no confusion] denotes the maximum of |f(z)| on the circle |z| = r, it follows from Liou-ville’s theorem that M(r, f) increases more rapidly than any power of r. Thus, to study the growth of the function we have to compare with exponentials.