Enneagrammic duoprism

The enneagrammic duoprism or stedip, also known as the enneagrammic-enneagrammic duoprism, the 9/2 duoprism or the 9/2-9/2 duoprism, is a noble uniform duoprism that consists of 18 enneagrammic prisms and 81 vertices.

The name can also refer to the great enneagrammic duoprism or the enneagrammic-great enneagrammic duoprism.

Vertex coordinates
The vertex coordinates of an enneagrammic duoprism, centered at the origin and with edge length 2sin(2π/9), are given by:
 * (1, 0, 1, 0),
 * (1, 0, cos(2π/9), ±sin(2π/9)),
 * (1, 0, cos(4π/9), ±sin(4π/9)),
 * (1, 0, cos(6π/9), ±sin(6π/9)),
 * (1, 0, cos(8π/9), ±sin(8π/9)),
 * (cos(2π/9), ±sin(2π/9), 1, 0),
 * (cos(2π/9), ±sin(2π/9), cos(2π/9), ±sin(2π/9)),
 * (cos(2π/9), ±sin(2π/9), cos(4π/9), ±sin(4π/9)),
 * (cos(2π/9), ±sin(2π/9), cos(6π/9), ±sin(6π/9)),
 * (cos(2π/9), ±sin(2π/9), cos(8π/9), ±sin(8π/9)),
 * (cos(4π/9), ±sin(4π/9), 1, 0),
 * (cos(4π/9), ±sin(4π/9), cos(2π/9), ±sin(2π/9)),
 * (cos(4π/9), ±sin(4π/9), cos(4π/9), ±sin(4π/9)),
 * (cos(4π/9), ±sin(4π/9), cos(6π/9), ±sin(6π/9)),
 * (cos(4π/9), ±sin(4π/9), cos(8π/9), ±sin(8π/9)),
 * (cos(6π/9), ±sin(6π/9), 1, 0),
 * (cos(6π/9), ±sin(6π/9), cos(2π/9), ±sin(2π/9)),
 * (cos(6π/9), ±sin(6π/9), cos(4π/9), ±sin(4π/9)),
 * (cos(6π/9), ±sin(6π/9), cos(6π/9), ±sin(6π/9)),
 * (cos(6π/9), ±sin(6π/9), cos(8π/9), ±sin(8π/9)),
 * (cos(8π/9), ±sin(8π/9), 1, 0),
 * (cos(8π/9), ±sin(8π/9), cos(2π/9), ±sin(2π/9)),
 * (cos(8π/9), ±sin(8π/9), cos(4π/9), ±sin(4π/9)),
 * (cos(8π/9), ±sin(8π/9), cos(6π/9), ±sin(6π/9)),
 * (cos(8π/9), ±sin(8π/9), cos(8π/9), ±sin(8π/9)).