Description
The
bipyramid over a
Polyhedron in nspace is constructed by embedding the Polyhedron into (n+1)space, computing the barycentre of the vertices, which is a point in the relative interior, and taking the convex hull of the embedded Polyhedron and the barycentre
x {+/ 1}.
As an example, we construct the octahedron as the bipyramid over the square (see
hypercube).
i1 : P = hypercube 2
o1 = P
o1 : Polyhedron

i2 : Q = bipyramid P
Compute barycenter.
Compute barycenter done.
o2 = Q
o2 : Polyhedron

i3 : vertices Q
o3 =  1 1 1 1 0 0 
 1 1 1 1 0 0 
 0 0 0 0 1 1 
3 6
o3 : Matrix QQ < QQ
