Cauchy–Riemann equations

E239285

The Cauchy–Riemann equations are fundamental conditions in complex analysis that characterize when a complex-valued function is holomorphic (complex differentiable).

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Cauchy–Riemann equations canonical 4

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Statements (47)

Predicate Object
instanceOf mathematical condition
system of partial differential equations
alternativeForm polar coordinates
appliesTo complex-valued functions of a complex variable
characterizes complex differentiable functions
holomorphic functions
conditionType necessary condition for complex differentiability
sufficient condition for complex differentiability under mild regularity assumptions
coordinateForm cartesian coordinates
domainVariable z = x + i y
ensures infinite real differentiability of holomorphic functions
local power series expansion of holomorphic functions
real analyticity of holomorphic functions
equivalentTo existence of complex derivative at a point with continuity in a neighborhood
failsFor absolute value map z ↦ |z|
complex conjugation map z ↦ z̄
field complex analysis
generalization CR-structures in several complex variables
Cauchy–Riemann–Fueter equations in quaternionic analysis
historicalPeriod 19th century mathematics
imaginaryPartNotation v(x,y)
implies conformality at noncritical points
direction-independent complex derivative
harmonicity of imaginary part
harmonicity of real part
mathematicalContext functions from open subsets of ℂ to ℂ
namedAfter Augustin-Louis Cauchy
Bernhard Riemann
polarForm ∂u/∂r = (1/r) ∂v/∂θ
∂v/∂r = −(1/r) ∂u/∂θ
realPartNotation u(x,y)
regularityAssumption continuity of first partial derivatives
relatedConcept Wirtinger derivatives
relatedTo Laplace equation
analytic functions
conformal mappings
requires real differentiability of component functions
role criterion for analyticity
foundational tool in complex function theory
standardForm ∂u/∂x = ∂v/∂y
∂u/∂y = −∂v/∂x
usedIn complex potential theory
proofs of analyticity of power series
two-dimensional elasticity theory
two-dimensional electrostatics
two-dimensional fluid dynamics
wirtingerForm ∂f/∂z̄ = 0 for holomorphic functions

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Referenced by (4)

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

Augustin-Louis Cauchy knownFor Cauchy–Riemann equations
Augustin-Louis notableFor Cauchy–Riemann equations
subject surface form: Augustin-Louis Cauchy
Cauchy integral formula relatedTo Cauchy–Riemann equations
Differential Analysis on Complex Manifolds topic Cauchy–Riemann equations