Definition:Divergent Improper Integral

Definition
An improper integral of a real function $f$ is said to diverge in any of the following cases:


 * $f$ is continuous on $[a..+\infty)$ and the limit $\displaystyle \lim_{b \to +\infty} \int_a^b f \left({x}\right) \ \mathrm dx$ does not exist,


 * $f$ is continuous on $(-\infty..b]$ and the limit $\displaystyle \lim_{a \to -\infty} \int_a^b f \left({x}\right) \ \mathrm dx$ does not exist,


 * $f$ is continuous on $[a..b)$, has an infinite discontinuity at $b$, and the limit $\displaystyle \lim_{c \to b^-} \int_a^c f \left({x}\right) \ \mathrm dx$ does not exist,


 * $f$ is continuous on $(a..b]$, has an infinite discontinuity at $a$, and the limit $\displaystyle \lim_{c \to a^+} \int_c^b f \left({x}\right) \ \mathrm dx$ does not exist.