Imagine these surfaces built from pieces which sit in a “brick” and meet the brick's 6 faces in convex curves. Reflection in the planes of these curves extends the surface to a larger one. Eventually it fills R^3. It has translation symmetries in 3 directions, hence it is called “triply periodic”.

### About the Schwarz PD Family

This is a 2-parameter family of triply periodic genus 3 surfaces.
In each case the original surface and the conjugate surface are
embedded. The most symmetric example (with a cubic lattice)
which is obtained when cc = 0, dd = 0, was already
constructed by H. A. Schwarz. When Alan Schoen
found more triply periodic surfaces around 1970 he named the
two surfaces which Schwarz found the P-surface (P for cubic
primitive) and the D-surface (D for diamond). He also found a
third embedded(!) surface in the associate family of these, the
Gyroid (associate parameter 0.577 which is approx. 52 degrees).
If dd=0 then a fundamental cell for the lattice is a prisma with
square base, in the morphing cc changes the height of the prisma.

K. Grosse-Brauckmann, M. Wohlgemuth: The Gyroid is embedded
and has constant mean curvature companions.
To appear Calc. Var. 1996

For a discussion of techniques for creating minimal surfaces with various qualitative features by appropriate choices of Weierstrass data, see either [KWH], or pages 192--217 of [DHKW].

- [KWH] H. Karcher, F. Wei, and D. Hoffman, The genus one helicoid, and the minimal surfaces that led to its discovery, in “Global Analysis in Modern Mathematics, A Symposium in Honor of Richard Palais' Sixtieth Birthday”, K. Uhlenbeck Editor, Publish or Perish Press, 1993
- [DHKW] U. Dierkes, S. Hildebrand, A. Kuster, and O. Wohlrab, Minimal Surfaces I, Grundlehren der math. Wiss. v. 295 Springer-Verlag, 1991