Math 2.0

Differential geometry Minimal and constant mean curvature surfaces Theorem

Weierstrass–Enneper parameterization

Builds on Minimal surfaceHolomorphic functionMeromorphic functionSimply connected domainConformal map

Statement

Let U⊂ℂU \subset \C be a simply connected domain and let z0∈Uz_0 \in U. Let ff be a holomorphic function on UU and gg a meromorphic function on UU. Assume that the zeros of ff are exactly the poles of gg. Assume also that at a pole of gg of order mm, the function ff has a zero of order exactly 2m2m. For z∈Uz \in U, let x1(z)=Re⁡∫z0zf(w) (1−g(w)2)2 dw,x2(z)=Re⁡∫z0zif(w) (1+g(w)2)2 dw,x3(z)=Re⁡∫z0zf(w)g(w) dw.x_1(z) = \operatorname{Re} \int_{z_0}^{z} \frac{f(w)\,(1 - g(w)^2)}{2} \, dw, \quad x_2(z) = \operatorname{Re} \int_{z_0}^{z} \frac{i f(w)\,(1 + g(w)^2)}{2} \, dw, \quad x_3(z) = \operatorname{Re} \int_{z_0}^{z} f(w) g(w) \, dw. Then x=(x1,x2,x3) ⁣:U→ℝ3x = (x_1, x_2, x_3) \colon U \to \R^3 is a conformal immersion whose image is a minimal surface. Conversely, after a rotation of ℝ3\R^3 if needed, every conformal minimal immersion of UU into ℝ3\R^3 arises in this way.

Remarks

The idea of the proof: for a conformal immersion xx, write φk=2 ∂xk/∂z\varphi_k = 2\,\partial x_k / \partial z. The surface is minimal exactly when each xkx_k is harmonic, that is, when each φk\varphi_k is holomorphic. Conformality is the equation φ12+φ22+φ32=0\varphi_1^2 + \varphi_2^2 + \varphi_3^2 = 0. The substitution f=φ1−iφ2f = \varphi_1 - i\varphi_2 and g=φ3/(φ1−iφ2)g = \varphi_3 / (\varphi_1 - i\varphi_2) solves this equation, and it gives back the integrands above. The condition on zeros and poles makes the integrands holomorphic and keeps (φ1,φ2,φ3)(\varphi_1, \varphi_2, \varphi_3) nonzero, so xx is an immersion.

The data f=2f = 2 and g(z)=zg(z) = z on ℂ\C give the Enneper surface. The function gg is the Gauss map of the surface followed by stereographic projection. Simple connectivity of UU makes the integrals independent of the path; on other domains one must check that the real parts of the periods vanish.

Going deeper

For a student

The representation is the main tool for constructing complete minimal surfaces, such as Costa's minimal surface. On a Riemann surface that is not simply connected, the same formulas work once the real periods of the three forms vanish; this period problem is usually the hardest step. Because gg is the Gauss map, curvature questions become questions about meromorphic functions. For example, the total curvature of a complete minimal surface of finite total curvature is −4π-4\pi times the degree of gg.

Reading path

To understand this page from the ground up, read these 6 pages in order. The foundations come first.

Show the path as a graph
Each page uses the pages above it. The colour of the bar on a box shows how strong the evidence is, and the box also gives it as text. The list has the same pages.
  • no evidence level
  1. Conformal map concept
  2. Holomorphic function concept
  3. Meromorphic function concept
  4. Minimal surface concept
  5. Simply connected domain concept
  6. Weierstrass–Enneper parameterization statement

Further reading

  1. Web https://en.wikipedia.org/wiki/Weierstrass–Enneper_parameterization
About this page
TagYWV6J23AP6
URIm2://YWV6J23AP6
Kindstatement, theorem
WritingW0 stub
MSC53A10, 30F45
StatusThis copy of the site has no build data. Run m2 status YWV6J23AP6.
AboutMinimal surface
UsesMinimal surface, Holomorphic function, Meromorphic function, Simply connected domain, Conformal map
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Changed2 November 2026

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