Cauchy's integral formula states that f(z_0) = 1/(2π i) ∮_γ (f(z) d z)/(z - z_0), where the integral is a contour integral along the contour γ enclosing the point z_0.

argument principle | Cauchy integral theorem | complex residue | contour integral | Morera's theorem | pole

Augustin-Louis Cauchy