 If a spheroid is parameterized as

where is the "reduced" or "parametric latitude", is the longitude, and and , then its Gaussian curvature is

and its mean curvature is

Both of these curvatures are always positive, so that every point on a spheroid is elliptic.The aspect ratio of an oblate spheroid/ellipse, , is the ratio of the polar to equatorial lengths, while the flattening (also called oblateness) , is the ratio of the equatorial-polar length difference to the equatorial length