A ring torus with aspect ratio 3, the ratio between the diameters of the larger (blue) circle and the smaller (red) circle. The two radii coordinates are shown as well. The radius denoted by capital, R, is the distance from the geometric center of the outer ring lying outside the volume, to the center of the inner ring. The radius denoted by lower case, r, is the distance from the inner ring’s center to the surface of the torus.
(echo:: @ ᯤ)