Editing Incomplete gamma function (section)

======Sectors======
Sectors in {{math|'''C'''}} having their vertex at {{math|1=''z'' = 0}} often prove to be appropriate domains for complex expressions. A sector {{mvar|D}} consists of all complex {{mvar|z}} fulfilling {{math|''z'' ≠ 0}} and {{math|''α'' − ''δ'' < arg ''z'' < ''α'' + ''δ''}} with some {{mvar|α}} and {{math|0 < ''δ'' ≤ ''π''}}. Often, {{mvar|α}} can be arbitrarily chosen and is not specified then. If {{mvar|δ}} is not given, it is assumed to be {{pi}}, and the sector is in fact the whole plane {{math|'''C'''}}, with the exception of a half-line originating at {{math|1=''z'' = 0}} and pointing into the direction of {{math|−''α''}}, usually serving as a [[Branch cut#Branch cuts|branch cut]]. Note: In many applications and texts, {{mvar|α}} is silently taken to be 0, which centers the sector around the positive real axis.