Definition:Integrable Function/Unbounded

Definition
Let $f: \R \to \R$ be a real function.

Let $f$ be unbounded on the open interval $\openint a b$.

Let:
 * $f^+$ denote the positive part of $f$
 * $f^-$ denote the negative part of $f$

that is:

Let $f^+$ and $f^-$ both be integrable on $\openint a b$.

Then $f$ is integrable on $\openint a b$ and its (definite) integral is understood to be:


 * $\ds \int_a^b \map f x \rd x := \int_a^b \map {f^+} x \rd x - \int_a^b \map {f^-} x \rd x$