+The **Cauchy–Riemann equations** are a pair of partial differential equations fundamental to [Complex Analysis](/wiki/Complex_Analysis). They establish a necessary and sufficient condition for a [complex function](/wiki/Complex_Function) to be differentiable at a point, defining what it means for such a function to be analytic or holomorphic.
+## See also
+- [Holomorphic Function](/wiki/Holomorphic_Function)
+- [Harmonic Function](/wiki/Harmonic_Function)
+- [Partial Differential Equation](/wiki/Partial_Differential_Equation)
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