diameter.box3 computes the diameter of the box.
volume.box3 computes the volume of the box.
shortside.box3 finds the shortest of the three side lengths
of the box.
sidelengths.box3 returns all three side lengths
of the box.
eroded.volumes computes, for each entry r[i],
the volume of the smaller box obtained by removing a slab of
thickness r[i] from each face of the box. This smaller box is
the subset consisting of points that lie at least r[i] units
away from the boundary of the box.