Elliptic Point

A point p on a Regular Surface $M\in\Bbb{R}^3$ is said to be elliptic if the Gaussian Curvature $K({\bf p})>0$ or equivalently, the Principal Curvatures $\kappa_1$ and $\kappa_2$ have the same sign.

See also Anticlastic, Elliptic Fixed Point (Differential Equations), Elliptic Fixed Point (Map), Gaussian Curvature, Hyperbolic Point, Parabolic Point, Planar Point, Synclastic

References

Gray, A. Modern Differential Geometry of Curves and Surfaces. Boca Raton, FL: CRC Press, p. 280, 1993.