Cauchy residue theorem

E239298

The Cauchy residue theorem is a fundamental result in complex analysis that relates contour integrals of analytic functions around singularities to the sum of their residues, greatly simplifying the evaluation of many complex and real integrals.

All labels observed (2)

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residue theorem 2
Cauchy residue theorem canonical 1

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Predicate Object
instanceOf result in complex analysis
theorem
appliesIn asymptotic analysis of integrals
electromagnetic theory
evaluation of Fourier integrals
evaluation of Laplace-type integrals
quantum field theory calculations
signal processing
appliesTo analytic functions with isolated singularities
meromorphic functions
assumes orientation of contour is positive (counterclockwise) in standard form
concerns isolated singularities
field complex analysis
formula ∮_γ f(z) dz = 2πi Σ Res(f, a_k) for singularities a_k inside γ
generalizes Cauchy integral formula
hasConsequence integral around a closed contour is zero if there are no singularities inside
sum of residues including at infinity can be zero in certain settings
hasExtension global residue theorem in several complex variables
residue theorem on Riemann surfaces
hasVariant version with winding number n(γ, a_k)
historicalPeriod 19th century mathematics
implies Cauchy integral theorem
isFoundationFor many contour integration techniques
residue calculus
isRelatedTo Jordan's lemma
Laurent series
Rouché's theorem
argument principle
isTaughtIn graduate analysis courses
undergraduate complex analysis courses
isToolFor evaluating complex integrals
evaluating improper integrals
evaluating integrals involving exponential functions
evaluating integrals involving rational functions
evaluating integrals involving trigonometric functions
evaluating real integrals via contour integration
namedAfter Augustin-Louis Cauchy
relates contour integrals
residues
requires contour to be closed
finite number of singularities inside the contour
function to be analytic on and inside the contour except at isolated singularities
statesThat the integral of a function around a closed contour equals 2πi times the sum of residues inside the contour
usesConcept Laurent series expansion
closed contour
residue of a complex function
winding number
variantFormula ∮_γ f(z) dz = 2πi Σ n(γ, a_k) Res(f, a_k)

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Referenced by (3)

Full triples — surface form annotated when it differs from this entity's canonical label.

Augustin-Louis Cauchy knownFor Cauchy residue theorem
Cauchy integral theorem relatedTo Cauchy residue theorem
this entity surface form: residue theorem
Cauchy integral formula relatedTo Cauchy residue theorem
this entity surface form: residue theorem