Complex analysis MOC

Residue

A residue of a meromorphic function at a Singular point is the value of the coëfficient of the Laurent series about .

Residues themselves can be used to calculate a contour integral using Cauchy's Residue Theorem.

Calculating residues

Cauchy's residue formula1 states that if has a pole of order at , then

In many cases, using the Laurent series is easier than using this formula.

Often L'Hôpital's Rule is involved in calculating residues.


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Footnotes

  1. 2023. Advanced Mathematical Methods, p. 61