Definition:Horizontal Asymptote

Definition
The horizontal line $y = L$ is a horizontal asymptote of the graph of a real function $f$ if either of the following limits exist:


 * $\displaystyle \lim_{x \mathop \to +\infty} \map f x = L_1$


 * $\displaystyle \lim_{x \mathop \to -\infty} \map f x = L_2$

Also see

 * Definition:Vertical Asymptote


 * At Most Two Horizontal Asymptotes