K3DSurf use parametric descriptions of it’s physical models. The parametric method of representing surfaces/curves uses a function to map some portion of R2 (the domain) to a patch of the surface in R3.

Because any position in the plane, and thus any position on the surface patch, can be uniquely given by two coordinates, the surface is said to be parameterized by those coordinates.

Parametric equations can be either “Implicit” or “Explicit”:

** Explicit equations:

In an explicit equations, x, y, and z are each given by separate functions of parameters u and v.

Example: X =u, Y = u+v, Z = cos(u+v)

** Implicit equations: Right now, only implicit equations like Z^n = f(X,Y) with (n mod 2 = 1) are supported by K3DSurf.

Example: Z = exp(x^2 + y^2), Z^7 = exp(x*cos(y))…

http://k3dsurf.s4.bizhat.com/k3dsurf-ftopic9-0-asc-15.html

http://k3dsurf.sourceforge.net