Gaussian curvature at a given point on a smooth surface = K1 x K2
- K1: largest curvature at that point
- K2: smallest curvature at that point
Formal descriptions of the Gaussian curvature can be found in these links:
- https://mathworld.wolfram.com/GaussianCurvature.html
- https://en.wikipedia.org/wiki/Gaussian_curvature
Also, I found this very readable exposition: Applications of Gaussian Curvature in Physics
The surface integral of the Gaussian curvature over some region of a surface is called the total curvature.
Suresh Emre
Renaissance Universal 